,illustration3 ,mariner spacecraft ,,mariner ,,mission ,,to ,,venus ,prepared for the ,national ,aeronautics and ,space ,administration ,,by ,,the ,,staff1 ,jet ,propulsion ,laboratory1 ,california ,institute of ,technology ,,compiled ,,by ,,harold ,j4 ,,wheelock ,,foreword ,,by ,w4 ,h4 ,,pickering1 ,director1 ,jet ,propulsion ,laboratory1 ,california ,institute of ,technology ,mc,g,r,a,w-,,hill ,,book ,,company1 ,,inc4 ,new ,york1 ,san ,francisco1 ,toronto1 ,london ,,mariner ,,mission ,,to ,,venus ,copyright #aifc by the ,jet ,propulsion ,laboratory1 ,california ,institute of ,technology4 ,all ,rights ,reserved4 ,printed in the ,united ,states of ,america4 ,library of ,congress ,catalog ,card ,number #fc-agdhi4 ,this book describes one phase of the ,u4 ,s4 civilian space program--the journey of the ,mariner spacecraft to the vicinity of ,venus and beyond4 ,it reports upon the measurements taken during the 8flyby0 on ,december #ad1 #aifb1 when ,mariner reached a point #ba1eih miles from the planet1 and #cf1jjj1jjj miles from ,earth 7communication with the spacecraft was continued up to a distance of approximately #ed1jjj1jjj miles from ,earth74 ,the ,mariner mission was a project of the ,national ,aeronautics and ,space ,administration1 carried out under ,contract ,no4 ,,nas #g-ajj by the ,jet ,propulsion ,laboratory1 ,california ,institute of ,technology4 ,,foreword ,for many centuries scientific information about the planets and the vast void that separates them has been collected by astronomers observing from the surface of the ,earth4 ,now1 with the flight of ,mariner ,,ii1 we suddenly have in our hands some #ij million bits of experimental data measured in the region between ,earth and the planet ,venus4 ,thus1 man for the first time has succeeded in sending his instruments far into the depths of space1 and indeed1 in placing them near another planet4 ,a whole new area of experimental astronomy has been opened up4 ,this book is a brief record of the ,mariner ,project to date and is designed to explain in general terms the preliminary conclusions4 ,actually1 it will be months or years before all of the data from ,mariner ,,ii have been completely analyzed4 ,the most important data were the measurements made in the vicinity of the planet ,venus1 but it should also be noted that many weeks of interplanetary environmental measurements have given us new insight into some of the basic physical phenomena of the solar system4 ,the trajectory data have provided new1 more accurate measurements of the solar system4 ,the engineering measurements of the performance of the spacecraft will be of inestimable value in the design of future spacecraft4 ,thus1 the ,mariner ,,ii spacecraft to ,venus not only looks at ,venus but gives space scientists and engineers information helpful in a wide variety of space ventures4 ,a project such as ,mariner ,,ii is first a vast engineering task4 ,many thousands of man-hours are required to design the complex automatic equipment which must operate perfectly in the harsh environment of space4 ,every detail of the system must be studied and analyzed4 ,the operations required to carry out the mission must be understood and performed with precision4 ,a successful mission requires every member of the entire project team to do his task perfectly4 ,whether it be the error of a designer1 mechanic1 mathematician1 technician1 operator1 or test engineer--a single mistake1 or a faulty piece of workmanship1 may cause the failure of the mission4 ,space projects abound with examples of the old saying1 8,for want of a nail1 the shoe was lost 44410 and so on1 until the kingdom is lost4 ,only when every member of the project team is conscious of his responsibility will space projects consistently succeed4 ,the ,mariner ,,ii ,project started with the ,lunar and ,planetary ,projects ,office of the ,office of ,space ,sciences at ,,nasa in ,washington4 ,jet ,propulsion ,laboratory1 ,california ,institute of ,technology1 personnel provided the main body of the team effort4 ,they were heavily supported by industrial contractors building many of the subassemblies of the spacecraft1 by scientists planning and designing the scientific experiments1 and by the ,air ,force which supplied the launching rockets4 ,several thousand men and women had some direct part in the ,mariner ,project4 ,it would be impossible to list all of those who made some special contribution1 but each and every member of the project performed his job accurately1 on time1 and to the highest standards4 ,mariner ,,ii is only a prelude to ,,nasa's program of unmanned missions to the planets4 ,missions to ,mars as well as ,venus will be carried out4 ,spacecraft will not only fly by the planets as did ,mariner ,,ii1 but capsules will be landed1 and spacecraft will be put into orbit about the planets4 ,the next mission in the ,mariner series will be a flyby of the planet ,mars in #aife4 ,by the end of the decade1 where will we be exploring1 what will new ,mariners have found8 ,will there be life on ,mars1 or on any other planet of the solar system8 ,what causes the red spot on ,jupiter8 ,what is at the heart of a comet8 ,these and many other questions await answers obtained by our future spacecraft4 ,mariner ,,ii is just a beginning4 ,w4 ,h4 ,pickering ,director ,jet ,propulsion ,laboratory ,california ,institute of ,technology ,april1 #aifc ,,contents ,,foreword ,,acknowledgments ,,chapter #a ,,venus ,the ,double ,star of the ,ancient ,world ,the ,consensus prior to ,mariner ,,ii ,the ,cytherean ,riddle3 ,living ,world or ,incinerated ,planet ,,chapter #b ,,preparing ,,for ,,space ,a ,problem in ,celestial ,dynamics ,the ,organization ,,nasa3 ,for ,science ,,jpl3 ,,jato to ,mariner ,general ,dynamics3 ,the ,atlas ,lockheed3 ,agena ,b ,,chapter #c ,,the ,,spacecraft ,the ,spaceframe ,the ,power ,system ,,cc,s3 ,the ,brain and the ,stopwatch ,telecommunications3 ,relaying the ,data ,attitude ,control3 ,balancing in ,space ,propulsion ,system ,temperature ,control ,the ,scientific ,instruments ,,chapter #d ,,the ,,launch ,,vehicle ,the ,atlas ,booster3 ,power of ,six #gjg's ,the ,agena ,b3 ,start and ,restart ,,chapter #e ,,flight ,,into ,,space ,mariner ,i3 ,an ,abortive ,launch ,mariner ,,ii3 ,a ,roll before ,parking ,the ,parking ,orbit ,orientation and ,midcourse ,maneuver ,the ,long ,cruise ,encounter and ,beyond ,the ,record of ,mariner ,,chapter #f ,,the ,,tracking ,,network ,deep ,space ,instrumentation ,facility ,the ,goldstone ,complex ,the ,woomera ,station ,the ,johannesburg ,station ,mobile ,tracking ,station ,,chapter #g ,,thirteen ,,million ,,words ,communication ,control ,the ,operations ,center ,central ,computing ,facility ,,chapter #h ,,the ,,scientific ,,experiments ,data ,conditioning ,system ,cosmic ,dust ,detector ,solar ,plasma ,experiment ,high-energy ,radiation ,experiment ,the ,magnetometer ,microwave ,radiometer ,infrared ,radiometer ,mariner's ,scientific ,objectives ,,chapter #i ,,the ,,legacy ,,of ,,mariner ,space without ,dust8 ,the ,ubiquitous ,solar ,wind ,high-energy ,particles3 ,fatal ,dosage8 ,a ,magnetic ,field8 ,the ,surface3 ,how ,hot8 ,cloud ,temperatures3 ,the ,infrared ,readings ,the ,radar ,profile3 ,measurements from ,earth ,,chapter #aj ,,the ,,new ,,look ,,of ,,venus ,,appendix ,,index ,,acknowledgments ,researching the material1 gathering and comparing data1 preparation of review drafts and attending to the hundreds of details required to produce a document on the results of such a program as the ,mariner mission to ,venus is a tremendous task4 ,special acknowledgment is made to ,mr4 ,harold ,j4 ,wheelock who1 on an extremely short time scale1 carried the major portion of this work to completion4 ,although the prime sources for the information were the ,planetary ,program office and the ,technical ,divisions of the ,jet ,propulsion ,laboratory1 other organizations were extremely helpful in providing necessary data1 notably the ,george ,c4 ,marshall ,space ,flight ,center1 the ,lockheed ,missiles and ,space ,company1 the ,astronautics ,division of the ,general ,dynamics ,corporation1 and1 of course1 the many elements of the ,national ,aeronautics and ,space ,administration4 ,,jpl technical information staff members who assisted ,mr4 ,wheelock in production of the manuscript and its illustrations were ,mr4 ,james ,h4 ,wilson1 ,mr4 ,arthur ,d4 ,beeman and ,mr4 ,albert ,e4 ,tyler4 ,,jpl is also grateful to ,mr4 ,chester ,h4 ,johnson for his help and suggestions in preparing the final manuscript4 ,,chapter #a ,,venus ,halfway between ,los ,angeles and ,las ,vegas1 the ,california country climbs southward out of the sunken basin of ,death ,valley onto the #cejj-;foot-high floor of the ,mojave desert4 ,on this immense plateau in an area near ,goldstone ,dry ,lake1 about #de miles north of the town of ,barstow1 a group of #he-;foot antennas forms the nucleus of the ,united ,states' world-wide1 deep-space tracking network4 ,here1 on the morning of ,december #ad1 #aifb1 several men were gathered in the control building beneath one of the antennas1 listening intently to the static coming from a loudspeaker4 ,they were surrounded by the exotic equipment of the space age4 ,through the window loomed the gleaming metal framework of an antenna4 ,suddenly a voice boomed from the loudspeaker3 8,the numbers are changing4 ,we're getting data60 ,the men broke into a cheer1 followed by an expectant silence4 ,again the voice came from the speaker3 8,the spacecraft's crossing the terminator 444 it's still scanning40 ,at that moment1 some #cf million miles from the ,earth1 the ,national ,aeronautics and ,space ,administration's ,mariner#a spacecraft was passing within #ba1fjj miles of the planet ,venus and was radioing back information to the ,goldstone ,station--the first scientific data ever received by man from the near-vicinity of another planet4 ,at the same time1 in ,washington1 ,d4,c41 a press conference was in progress4 ,mr4 ,james ,e4 ,webb1 ,administrator of the ,national ,aeronautics and ,space ,administration1 and ,dr4 ,william ,h4 ,pickering1 ,director of the ,jet ,propulsion ,laboratory1 stood before a bank of microphones4 ,in a few moments1 ,dr4 ,pickering said1 the audience would hear the sound of ,mariner ,,ii as it transmitted its findings back to the ,earth4 ,then1 a musical warble1 the voice of ,mariner ,,ii1 resounded in the hall and in millions of radios and television sets around the nation4 ,alluding to the ,greek belief that harmonious sounds accompanied the movement of the planets1 ,dr4 ,pickering remarked that this1 in truth1 was the music of the spheres4 ,mariner ,,ii had been launched from ,cape ,canaveral1 ,florida1 on ,august #bg1 #aifb4 ,its arrival at ,venus was the culmination of a #aji-;day journey through the strange environment of interplanetary space4 ,the project had gone from the drawing board to the launching pad in less than #aa months4 ,mariner had taxed the resources and the manpower of the ,jet ,propulsion ,laboratory1 ,california ,institute of ,technology2 the ,atlantic ,missile ,range centering at ,cape ,canaveral2 theoretical and experimental laboratories at several universities and ,,nasa centers2 numerous elements of the aerospace industry2 and1 of course1 ,,nasa management itself4 ,to the considerable body of engineers scattered around the world from ,pasadena to ,goldstone to ,south ,africa to ,australia1 the warble of ,mariner was something more than 8the music of the spheres40 ,intercept with ,venus was the climax of #aji days of hope and anxiety4 ,to the world at large1 this warbling tone was a signal that the ,united ,states had moved ahead--reached out to the planets4 ,mariner was exploring the future1 seeking answers to some of the unsolved questions about the solar system4 ,,the ,,double ,,star ,,of ,,the ,,ancient ,,world ,venus1 the glittering beacon of our solar system1 has intrigued man for at least #d1jjj years4 ,the ,babylonians first mentioned the brilliant planet on clay tablets as early as #b1jjj years before ,christ4 ,the ,egyptians1 the ,greeks1 and the ,chinese had thought of ,venus as two stars because it was visible first in the morning and then in the evening sky4 ,the ,greeks had called the morning star ,phosphorus and the evening star ,hesperos4 ,by #ejj ,b4,c4 ,pythagoras1 the ,greek philosopher1 had realized that the two were identical4 ,galileo discovered the phases of ,venus in #afaj4 ,because of the planet's high reflectivity1 ,copernicus falsely concluded that ,venus was either self-luminous or else transparent to the rays of the ,sun4 ,venus was tracked across the face of the ,sun in #agfa1 from which event the presence of an atmosphere about the planet was deduced because of the fuzzy edges of the image visible in the telescope4 ,throughout the eighteenth and nineteenth centuries1 ,venus continued to excite growing scientific curiosity in ,europe and ,america4 ,illustration3 ,venus' orbit is almost circular4 ,at inferior conjunction1 the planet is between the ,earth and the ,sun1 approximately #bf1jjj1jjj miles away2 at superior conjunction1 ,venus is on the other side of the ,sun4 ,the elongations are the farthest points to the east and the west of the ,earth4 ,even the development of giant telescopes and the refinement of spectroscopic and radar astronomy techniques in recent times had yielded few indisputable facts about ,venus4 ,until radar studies1 made from ,goldstone1 ,california1 in #aifb1 neither the rate nor the angle of axial spin could be determined with any degree of accuracy4 ,the ever-shifting atmosphere continued to shield the ,venusian surface from visual observation on ,earth1 and the nature of its atmosphere became an especially controversial mystery4 ,,the ,,consensus ,,prior ,,to ,,mariner ,,ii ,venus is a virtual twin of the ,earth2 it approaches our planet closer than any celestial body except the ,moon1 a few vagrant comets1 and other such galactic wanderers4 ,long fabled in song and legend as the most beautiful object in the sky1 ,venus has an albedo1 or reflectivity factor1 of #ei 7the ,moon has one of #g74 ,in its brightest or crescent phase1 ,venus glows like a torch1 even casting a distinct shadow--the only body other than the ,sun and the ,moon yielding such light4 ,venus' diameter is approximately #g1gjj miles1 compared with ,earth's #g1ijj4 ,also as compared with #a4j for the ,earth1 ,venus' mean density is #j4ia1 the mass #j4ha1 and the volume #j4ib4 ,the ,cytherean orbit 7the adjective comes from ,cytherea1 one of the ancient ,greek names for ,aphrodite--or in ,roman times1 ,venus--the goddess of love7 is almost a perfect circle1 with an eccentricity 7or out-of-roundness7 of only #j4jjfh1 lowest of all the planets4 ,venus rides this orbital path at a mean distance from the ,sun of #fg4b million miles 7,earth is #ic million miles71 and at a mean orbital speed of #gh1cjj miles per hour1 as compared with ,earth's #ff1fjj miles per hour4 ,it also has a shorter sidereal period 7revolution around the ,sun or year73 #bbd ,earth days1 #af hours1 #dh minutes4 ,estimates of the ,venus rotational period1 or the length of the ,venus day1 have ranged from approximately #bc ,earth hours to just over #bbd ,earth days4 ,the latter rotation rate would be almost equivalent to the ,venusian year and1 in such case1 the planet would always have the same face to the ,sun4 ,venus approaches within #bf million miles of the ,earth at inferior conjunction1 and is as far away as #afj million miles at superior conjunction1 when it is on the opposite side of the ,sun4 ,the escape velocity 7that velocity required to free an object from the gravitational pull of a planet7 on ,venus is #f4c miles per second1 compared with ,earth's escape velocity of #g miles per second4 ,the gravity of the ,earth is sufficient to trap an oxygen-bearing atmosphere near the terrestrial surface4 ,because the escape velocity of ,venus is about the same as that of ,earth1 men have long believed 7or hoped7 that the ,cytherean world might hold a similar atmosphere and thus be favorable to the existence of living organisms as we know them on the ,earth4 ,from this speculation1 numerous theories have evolved4 ,,the ,,cytherean ,,riddle3 ,,living ,,world ,,or ,,incinerated ,,planet ,before ,mariner ,,ii1 ,venus probably caused more controversy than any other planet in our solar system except ,mars4 ,observers have visualized ,venus as anything from a steaming abode of ,mesozoic-like creatures such as were found on the ,earth millions of years ago1 to a dead1 noxious1 and sunless world constantly ravaged by winds of incredible force4 ,conjectures about the ,venusian atmosphere have been inescapably tied to theories about the ,venusian topography4 ,because the clouds forming the ,venusian atmosphere1 as viewed from the ,earth through the strongest telescopes1 are almost featureless1 this relationship between atmosphere and topography has posed many problems4 ,impermanent light spots and certain dusky areas were believed by some observers to be associated with ,venusian oceans4 ,one scientist believed he identified a mountain peak which he calculated as rising more than #bg miles above the general level of the planet4 ,another feature of the ,venusian topography is the lack of 7detectable7 polar flattening4 ,the ,earth does have such a flattening at the poles and it was reasoned that1 because ,venus did not1 its rate of rotation must be much slower than that of the ,earth1 perhaps as little as only once during a ,venusian year1 thus keeping one face perpetually toward the ,sun4 ,another school of thought speculated that ,venus was covered entirely by vast oceans2 other observers concluded that these great bodies of water have long since evaporated and that the winds1 through the ,cytherean ages1 have scooped up the remaining chloride salts and blasted them into the ,venusian skies1 thus forming the clouds4 ,related to the topographic speculations were equally tenuous theories about its atmosphere4 ,it was reasoned that if the oceans of ,venus still exist1 then the ,venusian clouds may be composed of water droplets2 if ,venus were covered by water1 it was suggested that it might be inhabited by ,venusian equivalents of ,earth's ,cambrian period of #ejj million years ago1 and the same steamy atmosphere could be a possibility4 ,other theories respecting the nature of the ,venusian atmosphere1 depending on how their authors viewed the ,venusian terrain1 included clouds of hydrocarbons 7perhaps droplets of oil71 or vapors of formaldehyde and water4 ,finally1 the seemingly high temperature of the planet's surface1 as measured by ,earth-bound instruments1 was credited by some to the false indications that could be given by a ,cytherean ionosphere heavily charged with free electrons4 ,illustration3 ,as seen from ,earth1 ,venus is brightest at its crescent phases as shown in these six photographs made by the #ajj-;inch telescope at ,mt4 ,wilson1 ,california4 ,however1 the consensus of pre-,mariner scientific thinking seemed generally to indicate no detectable free oxygen in the atmosphere2 this fact inveighed against the probability of surface vegetation1 because ,earth-bound vegetation1 at least1 uses carbon dioxide and gives off oxygen into the atmosphere4 ,on the other hand1 a preponderance of carbon dioxide in the ,venusian atmosphere was measured which would create a greenhouse effect4 ,the heat of the ,sun would be trapped near the surface of the planet1 raising the temperature to as high as #fae degrees ,f4 ,if the topography were in truth relatively flat and the rate of rotation slow1 the heating effect might produce winds of #djj miles per hour or more1 and sand and dust storms beyond ,earthly experience4 ,and so the controversy continued4 ,but at #a3ec4ac4i a4m41 ,,est1 on ,august #bg1 #aifb1 the theories of the past few centuries were being challenged4 ,at that moment1 the night along the east ,florida coast was shattered by the roar of rocket engines and the flash of incandescent exhaust streams4 ,the ,united ,states was launching ,mariner ,,ii1 the first spacecraft that would successfully penetrate interplanetary space and probe some of the age-old mysteries of our neighbor planet4 ,,chapter #b ,,preparing ,,for ,,space ,in the summer of #aifa1 the ,united ,states was pushing hard to strengthen its position in the exploration of space and the near planets4 ,the ,national ,aeronautics and ,space ,administration was planning two projects1 both to be launched by an ,atlas booster and a ,centaur high-energy second stage capable of much better performance than that available from earlier vehicles4 ,the ,mariner program had two goals3 ,mariner ,a was ticketed for ,venus and ,mariner ,b was scheduled to go to ,mars4 ,caltech's ,jet ,propulsion ,laboratory had management responsibility under ,,nasa for both projects4 ,these spacecraft were both to be in the #a1jjj- to #a1bej-pound class4 ,launch opportunities for the two planets were to be best during the #aifb-aifd period and the new second-stage booster known as ,centaur was expected to be ready for these operations4 ,but trouble was developing for ,,nasa's planners4 ,by ,august1 #aifa1 it had become apparent that the ,centaur would not be flying in time to take advantage of the #aifb third-quarter firing period1 when ,venus would approach inferior conjunction with the ,earth4 ,,jpl studied the problem and advised ,,nasa that a proposed lightweight1 hybrid spacecraft combining certain design features of ,ranger ,,iii 7a lunar spacecraft7 and ,mariner ,a could be launched to ,venus in #aifb aboard a lower-powered ,atlas-,agena ,b launch vehicle4 ,illustration3 ,the ,mariner ,,ii spacecraft was launched by an ,atlas first-stage booster vehicle and an ,agena ,b second stage with restart capability4 ,,atlas-,,agena ,,adapter ,,agena ,b ,,mariner ,,spacecraft ,,shroud ,the proposed spacecraft would be called ,mariner ,r and was to weigh about #dfj pounds and carry #be pounds of scientific instruments 7later increased to #dj pounds74 ,the restart capability of ,agena was to be used in a #ih-statute-mile parking orbit4 7,the orbit was later raised to #aae statute miles and the spacecraft weight was reduced to about #ddg pounds47 ,two spacecraft would be launched one after the other from the same pad within a maximum launch period extending over #ef days from ,july to ,september1 #aifb4 ,the minimum launch separation between the two spacecraft would be #ba days4 ,as a result of the ,,jpl recommendations1 ,,nasa cancelled ,mariner ,a in ,september1 #aifa1 and assigned ,,jpl to manage a ,mariner ,r ,project to fly two spacecraft 7,mariner ,i and ,,ii7 to the vicinity of ,venus in #aifb4 ,scientific measurements were to be made in interplanetary space and in the immediate environs of the planet1 which would also be surveyed in an attempt to determine the characteristics of its atmosphere and surface4 ,scientific and engineering data would also be transmitted from the spacecraft to the ,earth while it was in transit and during the encounter with ,venus4 ,scientists and engineers were now faced with an arduous task4 ,within an #aa-month period1 on a schedule that could tolerate no delays1 two spacecraft had to be designed1 developed1 assembled1 tested1 and launched4 ,in order to meet the schedule1 tested flight assemblies and instruments would have to be in the ,pasadena assembly facility by mid-,january1 #aifb1 just four months after the start of the project4 ,probably no other major space project of similar scope had ever been planned on such a demanding schedule4 ,illustration3 ,mariner ,,ii travelled across #ahj million miles of space within our solar system as it spanned the gap between ,earth and ,venus 7shown here as the third and second planets1 respectively1 from the ,sun74 ,with the shipment of equipment to ,atlantic ,missile ,range 7,,amr7 scheduled for #i months after inception of the project1 management and design teams went all-out on a true 8crash0 effort4 ,quick decisions had to be made1 a workable design had to be agreed upon very early1 and1 once established1 the major schedule objectives could not be changed4 ,certain design modifications and manufacturing changes in the ,atlas-,agena launch vehicle were also necessary4 ,wherever possible1 ,ranger design technology had to be used in the new spacecraft and adapted to the requirements of a planetary probe4 ,other necessary tasks included trajectory calculation2 arrangements for launch1 space flight1 and tracking operations2 and coordination of ,,amr ,range support4 ,following ,,nasa's ,september1 #aifa decision to go ahead with the ,mariner ,r ,project1 ,,jpl's ,director1 ,dr4 ,william ,h4 ,pickering1 called on his seasoned team of scientists and engineers4 ,under ,robert ,j4 ,parks1 ,planetary ,program ,director1 ,jack ,n4 ,james was appointed as ,project ,manager for ,mariner ,r1 assisted by ,w4 ,a4 ,collier4 ,dan ,schneiderman was appointed ,spacecraft ,system ,manager1 and ,dr4 ,eberhardt ,rechtin headed the space tracking program1 with supervision of the ,deep ,space ,instrumentation ,facility 7,,dsif7 operations under ,dr4 ,nicholas ,renzetti4 ,the ,mariner space flight operations were directed by ,marshall ,s4 ,johnson4 ,a ,,problem ,,in ,,celestial ,,dynamics ,in order to send ,mariner close enough to ,venus for its instruments to gather significant data1 scientists had to solve aiming and guidance problems of unprecedented magnitude and complexity4 ,the #ddg-pound spacecraft had to be catapulted from a launching platform moving around the ,sun at #ff1fjj miles per hour1 and aimed so precisely that it would intercept a planet moving #gh1cjj miles per hour 7or #aa1gjj miles per hour faster than the ,earth7 at a point in space and time some #ahj4b million miles away and #aji days later1 with only one chance to correct the trajectory by a planned midcourse maneuver4 ,and the interception had to be so accurate that the spacecraft would pass ,venus within #h1jjj to #dj1jjj miles4 ,the chances of impacting the planet could not exceed #a in #a1jjj because ,mariner was not sterilized and might contaminate ,venus4 ,also1 much more data could be gathered on a near-miss flight path than on impact4 ,furthermore1 at encounter 7in the target area7 the spacecraft had to be so positioned that it could communicate with ,earth1 see the ,sun with its solar panels1 and scan ,venus at the proper angles4 ,along the way1 ,mariner had to be able to orient itself so that its solar panels were facing or 8locked onto0 the ,sun in order to generate its own power2 acquire and maintain antenna orientation to the ,earth2 correct its attitude constantly to hold ,earth and ,sun lock2 receive1 store1 and execute commands to alter its course for a closer approach to ,venus2 and communicate its findings to ,earth with only #c watts of radiated power and over distances never before spanned4 ,illustration3 ,mariner ,,ii was launched in a direction opposite to the orbital travel of the ,earth4 ,the ,sun's gravity then pulled it in toward the planet ,venus4 ,early in the program it had been decided that two spacecraft would be launched toward ,venus4 ,only #ef days were available for both launchings and the planet would not be close enough again for #ai months--the period between inferior conjunctions or the planet's closest approach to the ,earth4 ,on any one of these days1 a maximum of #b hours could be used for getting the vehicles off the launch pad4 ,in addition1 the ,mariners would have to leave the ,earth in a direction opposite to that of the ,earth's direction of orbital revolution around the ,sun4 ,this flight path was necessary so the spacecraft could then fall in toward the ,sun and intercept ,venus1 catching and passing the ,earth along the way1 about #fe days and #aa4e million miles out4 ,this feat of celestial navigation had to be performed while passing through the hostile environment of interplanetary space1 where the probe might be subjected to solar winds 7charged particles7 travelling at velocities up to #ejj miles per second2 intense bombardment from cosmic radiation1 charged protons1 and alpha particles moving perhaps #a4e million miles per hour2 radiated heat that might raise the spacecraft temperatures to unknown values2 and the unknown dangers from cosmic dust1 meteorites1 and other miscellaneous space debris4 ,in flight1 each spacecraft would have to perform more than #ij1jjj measurements per day1 reporting back to the ,earth on #eb engineering readings1 the changes in interplanetary magnetic fields1 the density and distribution of charged particles and cosmic dust1 and the intensity and velocity of low-energy protons streaming out from the ,sun4 ,at its closest approach to ,venus1 the spacecraft instruments would be required to scan the planet during a brief #ce-minute encounter1 to gather data that would enable ,earth scientists to determine the temperature and structure of the atmosphere and the surface1 and to process and transmit that data back to the ,earth4 ,,the ,,organization ,flying ,mariner to ,venus was a team effort made possible through the combined resources of several ,united ,states governmental organizations and their contractors1 science1 and industry4 ,the success of the ,mariner ,project resulted primarily from the over-all direction and management of the ,national ,aeronautics and ,space ,administration and the ,jet ,propulsion ,laboratory1 and the production and launch capabilities of the vehicle builders and the ,air ,force4 ,several organizations bore the major responsibility3 ,,nasa ,headquarters1 ,,jpl1 ,,nasa's ,marshall ,space ,flight ,center and ,launch ,operations ,center1 ,astronautics ,division of ,general ,dynamics1 and ,lockheed ,missiles and ,space ,company4 ,,nasa3 ,,for ,,science ,the ,national ,aeronautics and ,space ,administration was an outgrowth of the participation of the ,united ,states in the ,international ,geophysical ,year program and of the nation's space effort1 revitalized following ,russia's successful orbiting of ,sputnik ,i in #aieg4 ,illustration3 ,final ,,naca meeting1 ,august #ba1 #aieh4 ,illustration3 ,model of ,x-#a research plane4 ,illustration3 ,headquarters of ,national ,aeronautics and ,space ,administration1 ,washington1 ,d4,c4 ,illustration3 ,,jpl developed first ,,jato units in #aida4 ,illustration3 ,other ,laboratory ,projects were the ,corporal missile 7left7 and ,explorer ,i 7right71 the first ,u4,s4 satellite4 ,under the terms of the law which created ,,nasa1 it is a ,federal ,agency dedicated to carrying out 8activities in space 444 devoted to peaceful purposes for the benefit of all mankind40 ,,nasa is charged to preserve the role of our nation as a leader in the aeronautical and space sciences and technology and to utilize effectively the science and engineering resources of the ,united ,states in accomplishing these goals4 ,activities associated with military operations in space and the development of weapons systems are specifically assigned to the ,defense ,department4 ,in ,november1 #aieg1 before the creation of ,,nasa1 ,president ,eisenhower had established a ,scientific ,advisory ,committee to determine the national objectives and requirements in space and to establish the basic framework within which science1 industry1 and the academic community could best support these objectives4 ,the ,committee submitted a report to the ,president in ,march1 #aieh1 recommending creation of a civilian agency to conduct the national space programs4 ,the recommendation1 endorsed by the ,president1 was submitted to the ,congress on ,april #b1 #aieh4 ,the ,national ,aeronautics and ,space ,act of #aieh was passed and became law in ,july1 #aieh4 ,,nasa was officially established on ,october #a1 #aieh1 and ,dr4 ,t4 ,keith ,glennan1 ,president of ,case ,institute of ,technology1 was appointed as the first ,administrator4 ,the facilities and personnel of the ,national ,advisory ,committee for ,aeronautics 7,,naca7 were transferred to form the nucleus of the new ,,nasa agency4 ,,naca had performed important and significant research in aeronautics1 wind tunnel technology1 and aerodynamics since #aiae1 including a series of experimental rocket research aircraft that culminated in the ,x-#ae4 ,it was natural that it be expanded to include space operations4 ,among the ,,naca ,centers transferred to ,,nasa were the ,langley ,research ,center at ,hampton1 ,virginia2 ,lewis ,research ,center1 ,cleveland1 ,ohio2 ,ames ,research ,center1 ,moffett ,field1 ,california2 ,flight ,research ,center1 ,edwards1 ,california2 and the rocket launch facility at ,wallops ,island1 ,virginia4 ,those personnel of the ,naval ,research ,laboratory who had been working on ,project ,vanguard were also transferred to ,,nasa1 as was the project4 ,these personnel are now part of the new ,goddard ,space ,flight ,center at ,greenbelt1 ,maryland4 ,the ,october1 #aieh1 transfers also included a number of the space projects of the ,advanced ,research ,projects ,agency of the ,defense ,department4 ,in a ,december1 #aieh1 ,executive ,order1 the ,president assigned the former ,army facilities of the ,jet ,propulsion ,laboratory at ,pasadena1 ,california1 to ,,nasa4 ,at the same time1 the group working under ,dr4 ,wernher von ,braun at the ,army ,ballistic ,missile ,agency 7commanded by ,major ,general ,john ,b4 ,medaris7 was made responsive to ,,nasa requirements4 ,on ,july #a1 #aifj1 the ,george ,c4 ,marshall ,space ,flight ,center 7,,msfc7 was organized at ,huntsville under von ,braun's direction4 ,the former ,development ,operations ,division of ,,abma formed the nucleus of the new ,center4 ,the ,,msfc mission was to procure and to supervise the adaptation of launch vehicles for ,,nasa space missions1 including ,atlas1 ,thor1 and ,agena4 ,marshall is directly responsible for the design and development of advanced1 high-thrust booster vehicles such as the ,saturn ,c-#a and ,c-#e and the ,nova4 ,an agency to conduct ,,nasa affairs at ,cape ,canaveral was formed within ,,msfc on ,july #a1 #aifj4 ,known then as the ,launch ,operations ,directorate 7,,lod71 it was directed by ,dr4 ,kurt ,h4 ,debus4 ,,lod became independent of ,marshall in ,march1 #aifb1 when it was redesignated the ,launch ,operations ,center 7,,loc71 reporting directly to the ,office of ,manned ,space ,flight4 ,this separation resulted largely because the activities at ,,amr were becoming more operational in character and less oriented toward research and development4 ,,loc handles such functions for ,,nasa as the scheduling of launch dates and liaison with the ,atlantic ,missile ,range for support activities4 ,the ,center will have the responsibility in the field for assembly1 checkout1 and launch of the ,saturn and ,nova boosters4 ,following the election of ,president ,kennedy in #aifa1 ,james ,e4 ,webb replaced ,dr4 ,glennan as ,administrator of ,,nasa4 ,shortly after1 a new national goal was announced--placing a man on the ,moon and returning him safely to the ,earth in this decade4 ,meanwhile1 ,,jpl had been assigned responsibility for unmanned exploration of the ,moon1 the planets1 and interplanetary space1 and thus was charged with supporting the ,,nasa manned flight program through these activities4 ,in less than five years1 ,,nasa grew to include eight flight and research centers and about #ba1jjj technical and management personnel4 ,within ,,nasa1 ,dr4 ,abe ,silverstein's ,office of ,space ,flight ,programs was responsible for the ,mariner ,r ,project which was directly assigned to ,ed ,cortright1 ,director of ,lunar ,planetary ,programs1 and ,fred ,kochendorfer1 who is ,,nasa's ,program ,chief for ,mariner4 ,a subsequent reorganization placed responsibility under ,dr4 ,homer ,newell's ,office of ,space ,sciences1 and ,oran ,nicks became ,director of ,lunar ,planetary ,programs4 ,,jpl3 ,,jato ,,to ,,mariner ,the ,jet ,propulsion ,laboratory1 staffed and operated for ,,nasa by ,california ,institute of ,technology1 had long been active in research and development in the fields of missiles1 rockets1 and the space-associated sciences4 ,the first government-sponsored rocket research group in the ,united ,states1 ,,jpl had originated on the ,caltech campus in #aici1 an outgrowth of the ,guggenheim ,aeronautical ,laboratories1 then headed by celebrated aerodynamicist ,dr4 ,theodore von ,karman4 ,von ,karman and his associates moved their operation to a remote spot at the foot of the ,san ,gabriel mountains and1 working from this base1 in #aida the pioneering group developed the first successful jet-assisted aircraft takeoff 7,,jato7 units for the ,army ,air ,force4 ,the ,laboratory began a long association with the ,army ,ordnance ,corps in #aidd1 when the ,private ,a test rocket was developed4 ,in retrospect1 it is now recognized that the ,private ,a was the first ,u4 ,s4 surface-to-surface1 solid-propellant rocket4 ,its range was #aj miles6 ,,jpl's ,,wac ,corporal rocket set a ,u4 ,s4 high-altitude record of #dc4e miles in #aide4 ,mounted on a ,german ,v-#b as the ,bumper-,,wac1 it achieved an altitude record of #bej miles in #aidg4 ,more important1 this event was the first successful in-flight separation of a two-stage rocket--the feasibility of space exploration had been proved4 ,after the end of ,world ,war ,,ii1 ,,jpl research set the stage for high-energy solid-propellant rockets4 ,for the first time the solid propellants1 which contained both fuel and oxidizers1 were cast in thin-walled cases4 ,techniques were then developed for bonding the propellants to the case1 and burning radially outward from the central axis was achieved4 ,attention was then turned to increasing the energy of the propellants4 ,by #aidg1 the ,corporal ,e1 a new liquid-propellant research rocket1 was being fired4 ,,jpl was asked to convert it into a tactical weapon in #aidi4 ,the ,corporal ,e then became the first liquid-propellant surface-to-surface guided missile developed by the ,united ,states or the ,western bloc of nations4 ,because of the need for higher mobility and increased firing rate1 ,,jpl later designed and developed the solid-propellant ,sergeant--the nation's first 8second-generation0 weapon system4 ,this inertially guided missile was immune to electronic countermeasures by an enemy4 ,meanwhile1 ,,jpl scientists had pioneered in the development of electronic telemetering techniques1 which permit an accurate monitoring of system performance while missiles are in flight4 ,by #aidd1 ,dr4 ,william ,h4 ,pickering1 a ,new ,zealand born and ,caltech-trained physicist who had worked with ,dr4 ,robert ,millikan in cosmic ray research1 had been placed in charge of the telemetering effort at ,,jpl4 ,pickering became ,director of the ,laboratory in #aied4 ,following the launching of ,sputnik ,i1 the ,army-,,jpl team which had worked on the ,jupiter ,c missile to test nose cones1 was assigned the responsibility for putting the first ,united ,states satellite into orbit as soon as possible4 ,in just #hc days1 a modified ,jupiter ,c launch vehicle was prepared1 an instrumented payload was assembled1 a network of space communications stations was established1 and ,explorer ,i was orbited on ,january #ca1 #aieh4 ,explorer was an instrumented assembly developed by ,,jpl and the ,state ,university of ,iowa4 ,it discovered the inner ,van ,allen radiation belt4 ,subsequently1 ,,jpl worked with the ,army on other projects to explore space and to orbit satellites4 ,among these were ,pioneer ,,iii1 which located the outer ,van ,allen ,belt1 and ,pioneer ,,iv1 the first ,u4 ,s4 space probe to reach ,earth-escape velocity and to perform a lunar fly-by mission4 ,,general ,,dynamics3 ,,the ,,atlas ,the launch vehicle for ,mariner was an ,atlas ,d booster with an ,agena ,b second stage4 ,historically1 ,atlas can be traced to ,october1 #aied1 when the former ,convair ,corporation 7later acquired by ,general ,dynamics7 was invited to submit proposals for research and development of four missile systems1 including a #e1jjj-mile intercontinental weapon4 ,in ,january1 #aidf1 ,convair assigned ,k4 ,j4 ,bossart to begin a study of two proposed types of #e1jjj-mile missiles3 one jet powered at subsonic speeds1 with wings for aerodynamic control2 the other a supersonic1 ballistic 7wingless and bullet-like71 rocket-powered missile capable of operating outside the ,earth's atmosphere4 ,illustration3 ,photo courtesy of ,general ,dynamics_/,astro ,atlas missiles in assembly facility at ,general ,dynamics_/,astronautics plant4 ,this was the beginning of ,project ,,mx-#ggd1 lineal ancestor of ,atlas4 ,after captive testing at ,san ,diego in #aidg1 three of the experimental missiles were test-launched at ,white ,sands ,proving ,ground in ,new ,mexico4 ,the first flight failed at #f1bjj feet after a premature engine burnout4 ,in #aidg1 the ,air ,force shelved the ,,mx-#ggd project4 ,however1 this brief program had proved the feasibility of three concepts later used in ,atlas3 swiveling engines for directional control2 lightweight1 pressurized airframe structures2 and separable nose cones4 ,the ,korean ,war stimulated the ,,icbm concept and1 in #aiea1 a new ,,mx-#aeic contract was awarded to ,convair to study ballistic and glide rockets4 ,by ,september1 #aiea1 ,convair was proposing a ballistic missile that would incorporate some of the features of the ,,mx-#ggd design4 ,a plan for an accelerated program was presented to the ,air ,force in #aiec4 ,after a year of study1 a full go-ahead for the project1 now called ,atlas1 was given in ,january1 #aiee4 ,the unit handling the ,atlas program was set up as ,convair ,astronautics1 with ,j4 ,r4 ,dempsey as president1 on ,march #a1 #aieg4 ,the first ,atlas test flight1 in ,june of #aieg1 ended in destruction of the missile when it went out of control4 ,following another abortive attempt1 the first fully successful flight of an ,atlas missile was made from ,cape ,canaveral on ,december #ag1 #aieg4 ,the ,atlas program was in full swing by #aieh1 when #ad test missions were flown4 ,the entire missile was orbited in ,december1 #aieh1 as ,project ,score4 ,it carried the voice of ,president ,eisenhower as a ,christmas message to the world4 ,the ,atlas missile system was accepted for field operations by the ,air ,force in #aieh4 ,also in #aieh1 an ,atlas achieved a new distance record1 flying more than #i1jjj miles down the ,atlantic ,missile ,range1 where it landed in the ,indian ,ocean1 off the ,south ,african coast4 ,atlas has been modified for use by ,,nasa as a space vehicle booster4 ,known as the ,atlas ,d1 it has launched lunar probes1 communications and scientific ,earth satellites1 and manned space vehicles4 ,,lockheed3 ,,agena ,b ,the ,lockheed ,agena ,b second-stage vehicle was mounted on top of the ,atlas booster in the launch of the ,mariner spacecraft4 ,the ,u4 ,s4 ,air ,force had first asked ,lockheed ,missiles and ,space ,division1 headed by ,l4 ,e4 ,root1 to work on an advanced orbital vehicle for both military and scientific applications in #aief4 ,on ,october #bi of that year1 ,lockheed was appointed prime weapon system contractor on the new ,agena ,project1 under the ,air ,force ,ballistic ,missile ,division4 ,in order to speed the program1 the ,thor missile was used as the booster stage for the early ,agena flights4 ,the ,atlas was also utilized in later operations4 ,in ,august1 #aieg1 the ,air ,force recommended that the program be accelerated as much as possible4 ,after ,russia orbited ,sputnik ,i in ,october of #aieg1 a further speed-up was ordered4 ,the first of the ,agena-,discoverer series was launched into orbit on ,february #bh1 #aiei1 with the ,thor missile as the booster4 ,the first restart in orbit occurred on ,february #ah1 #aifa1 when the new ,agena ,b configuration was used to put ,discoverer ,,xxi into orbit4 ,all of the ,,nasa missions using ,agena1 beginning with ,ranger ,i in ,august1 #aifa1 have been flown with the ,b model4 ,agena holds several orbiting records for ,u4 ,s4 vehicles4 ,the first water recovery followed the #ag orbits of ,discoverer ,,xiii on ,august #aa1 #aifj4 ,the first air recovery of a capsule from orbit occurred with ,discoverer ,,xiv on ,august #ah1 #aifj4 ,in all1 a total of #aa capsules were recovered from orbit1 #g in the air1 #d from the sea4 ,,chapter #c ,,the ,,spacecraft ,in the #aa brief months which ,,jpl had to produce the ,mariner spacecraft system1 there was no possibility of designing an entirely new spacecraft4 ,,jpl's solution to the problem was derived largely from the ,laboratory's earlier space exploration vehicles1 such as the ,vega1 the ,ranger lunar series1 and the cancelled ,mariner ,a4 ,wherever possible1 components and subsystems designed for these projects were either utilized or redesigned4 ,where equipment was purchased from industrial contractors1 existing hardware was adapted1 if practicable4 ,only a minimum of testing could be performed on newly designed equipment and lengthy evaluation of 8breadboard0 mock-ups was out of the question4 ,ready for launch1 the spacecraft measured #e feet in diameter and #i feet #aa inches in height4 ,with the solar panels and the directional antenna unfolded in the cruise position1 ,mariner was #af feet #f inches wide and #aa feet #aa inches high4 ,,the ,,spaceframe ,the design engineers were forced to work within the framework of the earlier spacecraft technology because of the time restrictions1 but ,mariner ,i and ,,ii could weigh only about half as much as the ,ranger spacecraft and just over one-third as much as the planned ,mariner ,a4 ,illustration3 ,mariner spacecraft with solar panels1 microwave radiometer1 and directional antenna extended in flight position4 ,principal components are shown4 ,,roll ,,axis ,,omniantenna ,,magnetometer ,,sensor ,,particle ,,flux ,,detectors 7,,geiger ,,tubes7 ,,radiometer ,,reference ,,horns ,,microwave ,,radiometer ,,infrared ,,radiometer ,,ion-,,chamber ,,cosmic ,,dust ,,detector ,,earth ,,sensor ,,solar ,,panel ,,command ,,antenna ,,solar ,,sail ,,attitude ,,control ,,gas ,,bottles ,,solar ,,plasma ,,detector ,,directional ,,antenna ,the basic structural unit of ,mariner was a hexagonal frame made of magnesium and aluminum1 to which was attached an aluminum superstructure1 a liquid-propelled rocket engine for midcourse trajectory correction1 six rectangular chassis mounted one on each face of the hexagonal structure1 a high-gain directional antenna1 the ,sun sensors1 and gas jets for control of the spacecraft's attitude4 ,the tubular1 truss-type superstructure extended upward from the base hexagon4 ,it provided support for the solar panels while latched under the shroud during the launch phase1 and for the radiometers1 the magnetometer1 and the nondirectional antenna1 which was mounted at the top of the structure4 ,the superstructure was designed to be as light as possible1 yet be capable of withstanding the predicted load stresses4 ,the six magnesium chassis mounted to the base hexagon housed the following equipment3 the electronics circuits for the six scientific experiments1 the communications system electronics2 the data encoder 7for processing data before telemetering it to the ,earth7 and the command electronics2 the attitude control1 digital computer1 and timing sequencer circuits2 a power control and battery charger assembly2 and the battery assembly4 ,the allotment of weights for ,mariner ,,ii forced rigid limitation in the structural design of the spacecraft4 ,as launched1 the weights of the major spacecraft subsystems were as follows3 ,structure #gg pounds ,solar panels #dh pounds ,electronics #adf pounds ,propulsion #cb pounds ,battery #cc pounds ,scientific experiments #da pounds ,miscellaneous equipment #gj pounds ,gross weight #ddg pounds ,,the ,,power ,,system ,mariner ,,ii was self-sufficient in power4 ,it converted energy from sunlight into electrical current through the use of solar panels composed of photoelectric cells which charged a battery installed in one of the six chassis on the hexagonal base4 ,the control1 switching1 and regulating circuits were housed in another of the chassis cases4 ,illustration3 ,this hexagonal frame1 constructed of magnesium and aluminum1 is the basic supporting structure around which the ,mariner spacecraft is assembled4 ,illustration3 ,plan view from top showing six magnesium chassis hinged in open position4 ,,view ,,looking ,,aft ,,assemblies ,,hinged ,,in ,,open ,,position ,,scientific ,,equipment ,,assembly ,i ,,communications ,,assembly ,,ii ,,data ,,encoder ,,and ,,command ,,assembly ,,iii ,,attitude ,,control ,,and ,,cc ,,and ,s ,,assembly ,,iv ,,power ,,assembly ,v ,,battery ,,assembly ,,vi ,the battery operated the spacecraft systems during the period from launch until the solar panels were faced onto the ,sun4 ,in addition1 the battery supplied power during trajectory maneuvers when the panels were temporarily out of sight of the ,sun4 ,it shared the demand for power when the panels were overloaded4 ,the battery furnished power directly for switching various equipment in flight and for certain other heavy loads of brief duration1 such as the detonation of explosive devices for releasing the solar panels4 ,illustration3 ,mariner spacecraft with solar panels in open position4 ,note extension to left panel to balance solar pressures in flight4 ,the ,mariner battery used sealed silver-zinc cells and had a capacity of #ajjj watt-hours4 ,it weighed #cc pounds and was recharged in flight by the solar panels4 ,the solar panels1 as originally designed1 were #fj inches long by #cj inches wide and contained approximately #ihjj solar cells in a total area of #bg square feet4 ,each solar cell produced only about #bcj one-thousandths of a volt4 ,the entire array was designed to convert the ,sun's energy to electrical power in the range between #adh and #bbb watts4 ,when a later design change required the extension of one panel in order to add more solar cells1 it was necessary to add a blank extension to the other panel in order to balance the solar pressure on the spacecraft4 ,in order to protect the solar cells from the infrared and ultraviolet radiation of the ,sun1 which would produce heat but no electrical energy1 each cell was shielded from these rays by a glass filter which was nevertheless transparent to the light which the cells converted into power4 ,the power subsystem electronics circuits were housed in another of the hexagon chassis cases4 ,this equipment was designed to receive and switch power either from the solar panels1 the battery1 or a combination of the two1 to a booster-regulator4 ,,cc,s3 ,,the ,,brain ,,and ,,the ,,stopwatch ,once the ,atlas booster lifted ,mariner off the launch pad1 the digital ,central ,computer and ,sequencer 7,,cc,s7 performed certain computations and provided the basic timing control for those spacecraft subsystems which required a sequenced programming control4 ,the ,,cc,s was designed to initiate the operations of the spacecraft in three distinct sequences or 8modes03 7#a7 the launch mode1 from launch through the cruise configuration2 7#b7 the midcourse propulsion mode1 when ,mariner readjusted its sights on ,venus2 and 7#c7 the encounter mode1 involving commands for data collection in the immediate vicinity of the planet4 ,the ,,cc,s timed ,mariner's actions as it travelled more than #ahj million miles in pursuit of ,venus4 ,a highly accurate electronic clock 7crystal-controlled oscillator7 scheduled the operations of the spacecraft subsystems4 ,the oscillator frequency of #cjg4b kilocycles was reduced to the #b1djj- and #djj-;cycle-per-second output required for the power subsystem4 ,the control oscillator also timed the issuance of commands by the ,,cc,s in each of the three operating modes of the spacecraft4 ,a #a-pulse-per-minute signal was provided for such launch sequence events as the extension of the solar panels #dd minutes after launch1 turning on power for the attitude control subsystem one hour after launch1 and for certain velocity correction commands during the midcourse maneuver4 ,illustration3 ,the spacecraft used two antennas for communication4 ,the omni-antenna 7top7 was utilized when the directional antenna 7bottom7 could not be pointed at the ,earth4 ,illustration3 ,this command antenna 7on solar panel7 was used to receive maneuver commands4 ,a #a-pulse-per-second signal was generated as a reference during the roll and pitch maneuvers in the midcourse trajectory correction phase4 ,one pulse was generated every #c4c hours in order to initiate the command to orient the directional antenna on the ,earth at #afg hours after launch4 ,finally1 one pulse every #af4g hours was used to readjust the ,earth-oriented direction of the antenna throughout the flight4 ,,telecommunications3 ,,relaying ,,the ,,data ,the telecommunications subsystem enabled ,mariner to receive and to decode commands from the ,earth1 to encode and to transmit information concerning space and ,mariner's own functioning1 and to provide a means for precise measurement of the spacecraft's velocity and position relative to the ,earth4 ,the spacecraft accomplished all these functions using only #c watts of transmitted power up to a maximum range of #ec4i million miles4 ,a data encoder unit1 with ,,cc,s sequencing1 timed the three phases of ,mariner's journey3 7#a7 ,in the launch mode1 only engineering data on spacecraft performance were transmitted2 7#b7 during the cruise mode1 information concerning space and ,mariner's own functioning was transmitted2 and 7#c7 while the spacecraft was in the vicinity of ,venus1 only scientific information concerning the planet was to be transmitted4 7,the ,,cc,s failed to start the third mode automatically and it was initiated by radio command from the ,earth47 ,after the encounter with ,venus1 ,mariner was programmed to switch back to the cruise mode for handling both engineering and science data 7this sequence was also commanded by ,earth radio74 ,mariner ,,ii used a technique for modulating 7superimposing intelligent information7 its radio carrier with telemetry data known as phase-shift keying4 ,in this system1 the coded signals from the telemetry measurements displace another signal of the same frequency but of a different phase4 ,these displacements in phase are received on the ,earth and then translated back into the codes which indicate the voltage1 temperature1 intensity1 or other values measured by the spacecraft telemetry sensors or scientific instruments4 ,a continually repeating code1 almost noise-like both in sound and appearance on an oscilloscope1 was used for synchronizing the ground receiver decoder with the spacecraft4 ,this decoder then deciphered the data carried on the information channel4 ,this technique was called a two-channel1 binary-coded1 pseudo-noise communication system and it was used to modulate a radio signal for transmission1 just as in any other radio system4 ,radio command signals transmitted to ,mariner were decoded in a command subassembly1 processed1 and routed to the proper using devices4 ,a transponder was used to receive the commands1 send back confirmation of receipt to the ,earth1 and distribute them to the spacecraft subsystems4 ,mariner ,,ii used four antennas in its communication system4 ,a cone-like nondirectional 7omni7 antenna was mounted at the top of the spacecraft superstructure1 and was used from injection into the ,venus flight trajectory through the midcourse maneuver 7the directional antenna could not be used until it had been oriented on the ,earth74 ,a dish-type1 high-gain1 directional antenna was used at ,earth orientation and after the trajectory correction maneuver was completed4 ,it could receive radio signals at greater distances than the nondirectional antenna4 ,the directional antenna was nested beneath the hexagonal frame of the spacecraft while it was in the nose-cone shroud4 ,following the unfolding of the solar panels1 it was swung into operating position1 although it was not used until after the spacecraft locked onto the ,sun4 ,the directional antenna was equipped with flexible coaxial cables and a rotary joint4 ,it could move in two directions2 one motion was supplied by rolling the spacecraft around its long axis4 ,in addition1 two command antennas1 one on either side of one of the solar panels1 received radio commands from the ,earth for the midcourse maneuver and other functions4 ,,attitude ,,control3 ,,balancing ,,in ,,space ,mariner ,,ii had to maintain a delicate balance in its flight position during the trip to ,venus 7like a tight-wire walker balancing with a pole7 in order to keep its solar panels locked onto the ,sun and the directional antenna pointed at the ,earth4 ,otherwise1 both power and communications would have been lost4 ,a system of gas jets and valves was used periodically to adjust the attitude or position of the spacecraft4 ,expulsion of nitrogen gas supplied the force for these adjustments during the cruise mode4 ,while the spacecraft was subjected to the heavier disturbances caused by the rocket engine during the midcourse maneuver1 the gas jets could not provide enough power to control the attitude of the spacecraft and it was necessary to use deflecting vanes as rudders in the rocket engine exhaust stream for stabilizing purposes4 ,the attitude control system was activated by ,,cc,s command #fj minutes after launching4 ,it operated first to align the long axis of the spacecraft with the ,sun2 thus its solar panels would face the ,sun4 ,either the ,sun sensors or the three gyroscopes mounted in the pitch 7rocking back and forth71 yaw 7side to side71 and roll axes1 could activate the gas jet valves during the maneuver1 which normally required about #cj minutes to complete4 ,the spacecraft was allowed a pointing error of #a degree in order to conserve gas4 ,the system kept the spacecraft swinging through this #a degree of arc approximately once each #fj minutes4 ,as it neared the limit on either side1 the jets fired for approximately _/ of a second to start the swing slowly in the other direction4 ,thus1 ,mariner rocked leisurely back and forth throughout its #d-month trip4 ,sensitive photomultiplier tubes or electric eyes in the ,earth sensor1 mounted on the directional antenna1 activated the gas jets to roll the spacecraft about the already fixed long axis in order to face the antenna toward the ,earth4 ,when the ,earth was 8acquired10 the antenna would then necessarily be oriented in the proper direction4 ,if telemetry revealed that ,mariner had accidentally fixed on the ,moon1 over-ride radio commands from the ,earth could restart the orientation sequence4 ,,propulsion ,,system ,the ,mariner propulsion system for midcourse trajectory correction employed a rocket engine that weighed #cg pounds with fuel and a nitrogen pressure system1 and developed #ej pounds of thrust for a maximum of #eg seconds4 ,the system was suspended within the central portion of the basic hexagonal structure of the spacecraft4 ,this retro-rocket engine used a type of liquid propellant known as anhydrous hydrazine and it was so delicately controlled that it could burn for as little as _/ of a second and increase the velocity of the spacecraft from as little as _/ of a foot per second to as much as #bjj feet per second4 ,the hydrazine fuel was stored in a rubber bladder inside a doorknob-shaped container4 ,at the ignition command1 nitrogen gas under #c1jjj-pound-per-square-inch pressure was forced into the propellant tank through explosively activated valves4 ,the nitrogen then squeezed the rubber bladder1 forcing the hydrazine into the combustion chamber4 ,illustration3 ,the midcourse propulsion system provides trajectory correction for close approach to ,venus4 ,,fuel ,,tank ,,nitrogen ,,tank ,,jet ,,vane ,,actuator 7,,one ,,of ,,four7 ,,thrust ,,chamber ,hydrazine1 a monopropellant1 requires a starting ignition for proper combustion4 ,in the ,mariner system1 nitrogen tetroxide starting or 8kindling0 fluid was injected into the propellant tank by a pressurized cartridge4 ,aluminum oxide pellets in the tank acted as catalysts to control the speed of combustion of the hydrazine4 ,the burning of the hydrazine was stopped when the flow of nitrogen gas was halted1 also by explosively activated valves4 ,,temperature ,,control ,mariner's #abi days in space presented some unique problems in temperature control4 ,engineers were faced with the necessity of achieving some form of thermal balance so that ,mariner would become neither too hot nor too cold in the hostile environment of space4 ,the spacecraft's temperature control system was made as thermally self-sufficient as possible4 ,paint patterns1 aluminum sheet1 thin gold plating1 and polished aluminum surfaces reflected and absorbed the proper amount of heat necessary to keep the spacecraft and its subsystems at the proper operating temperatures4 ,thermal shields were used to protect the basic hexagon components4 ,the upper shield1 constructed of aluminized plastic on a fiberglass panel1 protected the top of the basic structure and was designed for maximum immunity to ultraviolet radiation4 ,the lower shield was installed below the hexagon2 it was made of aluminum plastic faced with aluminum foil where it was exposed to the blast of the midcourse rocket engine exhaust4 ,illustration3 ,methods used to control the temperature of the ,mariner spacecraft in flight4 ,,chromate ,,conversion ,,coating ,,upper ,,thermal ,,shield ,,polished ,,aluminum ,,louvers ,,gold ,,plate ,,black ,,paint ,,lower ,,thermal ,,shield ,,white ,,paint ,the six electronics cases on the hexagon structure were variously treated1 depending upon the power of the components contained in each4 ,those of high power were coated with a good radiating surface of white paint2 assemblies of low power were provided with polished aluminum shields to minimize the heat loss4 ,the case housing the attitude control and ,,cc,s electronics circuits was particularly sensitive because the critical units might fail above #acj degrees ,f4 ,a special assembly was mounted on the face of this case2 it consisted of eight movable1 polished aluminum louvers1 each actuated by a coiled1 temperature-sensitive1 bimetallic element4 ,when the temperature rose1 the elements acted as springs and opened the louvers4 ,a drop in temperature would close them4 ,structures and bracket assemblies external to the basic hexagon were gold plated if made of magnesium1 or polished if aluminum4 ,thus protected1 these items became poor thermal radiators as well as poor solar absorbers1 making them relatively immune to solar radiation4 ,external cabling was wrapped in aluminized plastic to produce a similar effect4 ,the solar panels were painted on the shaded side for maximum radiation control properties4 ,other items were designed so that the internal surfaces were as efficient radiators as possible1 thus conserving the spacecraft's heat balance4 ,,the ,,scientific ,,instruments ,four instruments were operated throughout the cruise and encounter modes of ,mariner3 a magnetometer1 a solar plasma detector1 a cosmic dust detector1 and a combined charged-particle detector and radiation counter4 ,two radiometers were used only in the immediate vicinity of ,venus4 ,these instruments are described in detail in ,chapter #h4 ,,chapter #d ,,the ,,launch ,,vehicle ,the motive power of ,mariner itself was limited to a trajectory correction rocket engine and an ability1 by means of gas jets1 to keep its two critical faces pointing at the ,sun and the ,earth4 ,therefore1 the spacecraft had to be boosted out of the ,earth's gravitational field and injected into a flight path accurate enough to allow the trajectory correction system to alter the course to deliver the spacecraft close enough to ,venus to be within operating range of the scientific instruments4 ,the combined ,atlas-,agena ,b booster system which was selected to do the job had a total thrust of about #cgf1jjj pounds4 ,with this power1 ,atlas-,agena could put #e1jjj pounds of payload into a #cde-mile orbit1 propel #gej pounds on a lunar trajectory1 or launch approximately #djj pounds on a planetary mission4 ,this last capability would be taxed to the limit by the #ddg pounds of the ,mariner spacecraft4 ,,the ,,atlas ,,booster3 ,,power ,,of ,,six #gjg',s ,the #cfj1jjj pounds of thrust developed by the ,atlas ,d missile is equivalent to the thrust generated by the engines of six ,boeing #gjg jet airplanes4 ,all of this awesome power requires a gargantuan amount of fuel3 in less than #bj seconds1 ,atlas consumes more than a propeller-driven1 four-engine airplane burns in flying coast-to-coast nonstop4 ,illustration3 ,photo courtesy of ,general ,dynamics_/,astronautics ,this military version of the ,atlas missile is modified for ,,nasa space flights4 ,the ,atlas missile1 as developed by ,convair for the ,air ,force1 has a range of #f1cjj miles and reaches a top speed of #af1jjj miles per hour4 ,the missile has been somewhat modified for use by ,,nasa as a space booster vehicle4 ,its mission was to lift the second-stage ,agena ,b and the ,mariner spacecraft into the proper position and altitude at the right speed so that the ,agena could go into ,earth orbit1 preliminary to the takeoff for interplanetary space4 ,the ,atlas ,d has two main sections3 a body or sustainer section1 and a jettisonable aft1 or booster engine section4 ,the vehicle measures about #ajj feet in length 7with military nose cone7 and has a diameter of #aj feet at the base4 ,the weight is approximately #bge1jjj pounds4 ,no aerodynamic control surfaces such as fins or rudders are used4 ,the ,atlas is stabilized and controlled by 8gimbaling0 or swiveling the engine thrust chambers by means of a hydraulic system4 ,the direction of thrust can thus be altered to control the movements of the missile4 ,the aft section mounts two #aed1ejj-pound-thrust booster engines and the entire section is jettisoned or separated from the sustainer section after the booster engines burn out4 ,the #fj1jjj-pound-thrust sustainer engine is attached at the center line of the sustainer section4 ,two #a1jjj-pound-thrust vernier 7fine steering7 engines are installed on opposite sides of the tank section in the yaw or side-turn plane4 ,all three groups of engines operate during the booster phase4 ,only the sustainer and the vernier engines burn after staging 7when the booster engine section is separated from the sustainer section of the missile74 ,all of the engines use liquid oxygen and a liquid hydrocarbon fuel 7,,rp-#a7 which is much like kerosene4 ,dual turbopumps and valves control the flow of these propellants4 ,the booster engine propellants are delivered under pressure to the propellant or combustion chamber1 where they are ignited by electroexplosive devices4 ,each booster thrust chamber can be swiveled a maximum of #e degrees in pitch 7up and down7 and yaw 7from side to side7 about the missile centerline4 ,the sustainer engine is deflected #c degrees in pitch and yaw4 ,the outboard vernier engines gimbal to permit pitch and roll movement through #adj degrees of arc1 and yaw movement through #bj degrees toward the missile body and #cj degrees outward4 ,all three groups of engines are started and develop their full rated thrust while the missile is held on the launch pad4 ,after takeoff1 the booster engines burn out and are jettisoned4 ,the sustainer engine continues to burn until its thrust is terminated4 ,the swiveled vernier engines provide the final correction in velocity and missile attitude before they are also shut down4 ,the propellant tank is the basic structure of the forward or sustainer section of the ,atlas4 ,it is made of thin stainless steel and is approximately #ej feet long4 ,internal pressure of helium gas is used to support the tank structure1 thus eliminating the need for internal bracing structures1 saving considerable weight1 and increasing over-all performance of the missile4 ,the helium gas used for this purpose is expanded to the proper pressure by heat from the engines4 ,equipment pods on the outside of the sustainer section house the electrical and electronic units and other components of the missile systems4 ,the ,atlas uses a flight programmer1 an autopilot1 and the gimbaled engine thrust chamber actuators for flight control4 ,the attitude of the vehicle is controlled by the autopilot1 which is set for this automatic function before the flight4 ,guidance commands are furnished by a ground radio guidance system and computer4 ,the airborne radio inertial guidance system employs two radio beacons which respond to the ground radar4 ,a decoder on board the missile processes the guidance commands4 ,,the ,,agena ,b3 ,,start ,,and ,,restart ,launching ,mariner to ,venus required a second-stage vehicle capable of driving the spacecraft out of ,earth orbit and into a proper flight path to the planet4 ,illustration3 ,photo courtesy of ,lockheed ,missiles and ,space ,company ,the ,agena ,b second stage is hoisted to the top of the gantry at ,,amr4 ,the ,agena ,b used for this purpose weighs #a1gjj pounds1 is #fj inches in diameter1 and has an over-all length of #be feet1 varying somewhat with the payload4 ,the ,agena ,b fuel tanks are made of #j4jhj-;inch aluminum alloy4 ,the liquid-burning engine develops more than #af1jjj pounds of thrust4 ,the propellants are a form of hydrazine and red fuming nitric acid4 ,the ,agena can be steered to a desired trajectory by swiveling the gimbal-mounted engine on command of the guidance system4 ,the attitude of the vehicle is controlled either by gimbaling the engine or by ejecting gas from pneumatic thrusters4 ,the ,agena has the ability to restart its engine after it has already fired once to reach an ,earth orbital speed4 ,this feature makes possible a significant increase in payload and a change of orbital altitude4 ,a velocity meter ends the first and second burns when predetermined velocities have been reached4 ,after engine cutoff1 the major reorientation of the vehicle is achieved through gas jets controlled from an electronic programming device4 ,this system can turn the ,agena completely around in orbit1 or pitch it down for reentry into the atmosphere4 ,the attitude is controlled by an infrared1 heat-sensitive horizon scanner and gyroscopes4 ,the principal modification to the ,agena vehicle for the ,mariner ,,ii mission was an alteration to the spacecraft-,agena adapter in order to reduce weight4 ,,chapter #e ,,flight ,,into ,,space ,with the ,mariner ,r ,project officially activated in the fall of #aifa and the launch vehicles selected1 engineers proceeded at full speed to meet the difficult launch schedule4 ,a preliminary design was adopted in late ,september1 when the scientific experiments to be carried on board were also selected4 ,by ,october #b1 a schedule had been established that would deliver two spacecraft to the assembly building in ,pasadena by ,january #ae and #bi1 #aifb1 respectively1 with the spares to follow in two weeks4 ,during the week of ,november #f1 tests were underway to determine problems involved in mating a mock-up of the spacecraft with the ,agena shroud and adapter assembly4 ,a thermal control model of the spacecraft had already gone into the small space simulator at ,,jpl for preliminary temperature tests4 ,,mr-#a1 the first ,mariner scheduled for flight1 was in assembly immediately after ,january #h1 #aifb1 and the process was complete by the end of the month1 when electrical and magnetic field tests had been started4 ,at the same time1 assembly of ,,mr-#b was underway4 ,work on ,,mr-#a was a week ahead of schedule by the end of the month4 ,a full-scale temperature control model of the spacecraft went into the large space simulator on ,february #bf4 ,in mid-,march1 system tests began on both spacecraft and it was decided that the flight hardware would be tested only in the small simulator1 with the temperature control model continuing in the large chamber4 ,illustration3 ,technician wears hood and protective goggles while working on ,mariner spacecraft in ,space simulator chamber at ,jet ,propulsion ,laboratory1 ,pasadena4 ,on ,march #bf1 ,,mr-#a was subjected to full-scale mating tests with the shroud 7cover7 and the adapter for mounting the spacecraft on top of the ,agena4 ,,mr-#b was undergoing vibration tests during the week of ,april #af4 ,by ,april #cj1 ,,mr-#a had completed vibration tests and had been mapped for magnetic fields so that1 once compensated for1 they would not interfere with the magnetometer experiment in space4 ,a dummy run of ,,mr-#a was conducted on ,may #g and the spacecraft1 space flight center1 and computing equipment were put through a simulated operations test run during the same week4 ,by ,may #ad1 clean-up and final inspection by microscope had begun on ,,mr-#a1 ,,mr-#b1 and ,,mr-#c 7the latter spacecraft had been assembled from the spares74 ,soon after1 the first two van loads of equipment were shipped to ,cape ,canaveral4 ,the final system test of ,,mr-#a was completed on ,may #ba and the test of ,,mr-#b followed during the same week4 ,during the week of ,may #bh1 all three spacecraft and their associated ground support equipment were packed1 loaded1 and shipped to the ,atlantic ,missile ,range 7,,amr74 ,at the same time1 the ,atlas designated to launch ,,mr-#a went aboard a ,c-#acc freight aircraft at ,san ,diego4 ,on the same day1 an ,air ,force order grounded all ,c-#acc's for inspection and the plane did not depart until ,june #i4 ,by ,june #aa1 #aifb1 the firing dates had been established and both spacecraft were ready for launching4 ,the ,atlas booster had already been erected on the launch pad4 ,the dummy run and a joint flight acceptance test were completed on ,,mr-#a during the week of ,july #b4 ,final flight preparations and system test of ,,mr-#a and the system test of ,,mr-#b were concluded a week later4 ,thus1 in #cbd days1 a new spacecraft project had been activated2 the design1 assembly1 and testing had been completed2 and the infinite number of decisions pertaining to launch1 ,,amr ,range ,operations1 deep-space tracking1 and data processing activities had been made and implemented4 ,venus was approaching the ,earth at the end of its #ai-month excursion around the ,sun4 ,the launch vehicles and ,mariners ,i and ,,ii stood ready to go from ,canaveral's ,launch ,complex #ab4 ,the events leading to the first close-up look at ,venus and intervening space were about to reach their first crisis3 a fiery explosion over the ,atlantic ,ocean4 ,,mariner ,i3 ,,an ,,abortive ,,launch ,after #egj hours of testing1 ,mariner ,i was poised on top of the ,atlas-,agena launch vehicle during the night of ,july #bj1 #aifb4 ,the time was right1 the ,range and the tracking net were standing by1 the launch vehicles were ready to cast off the spacecraft for ,venus4 ,illustration3 ,atlas for launching ,mariner ,,ii arrives at ,cape ,canaveral in ,c-#acc aircraft4 ,the countdown was begun at #aa3cc p4m41 ,,est1 ,july #bj1 after several delays because of trouble in the ,range ,safety ,command system4 ,at the time1 the launch count stood at ,t minus #agf minutes--if all went well1 #agf minutes until the booster engines were ignited4 ,another hold again delayed the count until #ab3cg a4m41 ,july #ba1 when counting was resumed at ,t minus #afe minutes4 ,the count then proceeded without incident to ,t minus #gi minutes at #b3bj a4m41 when uncertainty over the cause of a blown fuse in the ,range ,safety circuits caused the operations to be 8scrubbed0 or cancelled for the night4 ,the next launch attempt was scheduled for ,july #ba-bb4 ,the second launch countdown for ,mariner ,i began shortly before midnight1 ,july #ba4 ,spacecraft power had been turned on at #aa3jh p4m41 with the launch count at ,t minus #bjj minutes4 ,at ,t minus #ace minutes1 the weather looked good4 ,a #da-minute hold was required at minus #acj minutes 7#ab3ag a4m41 ,july #bb7 in order to change a noisy component in the ground tracking system4 ,when counting was resumed at ,t minus #acj minutes1 the clock read #ab3dh a4m4 ,a previously scheduled hold was called at ,t minus #fj minutes1 lasting from #a3eh to #b3ch a4m4 ,the good weather still held4 ,at ,t minus #hj seconds1 power fluctuations in the radio guidance system forced a #cd-minute hold4 ,time was resumed at #d3af a4m41 when the countdown was set back to ,t minus #e minutes4 ,at exactly #d3ba4bc a4m41 ,,est1 the ,atlas thundered to life and lifted off the pad1 bearing its ,venus-bound load4 ,the boost phase looked good until the ,range ,safety officer began to notice an unscheduled yaw-left 7northeast7 maneuver4 ,by #d3be a4m41 it was evident that1 if allowed to continue1 the vehicle might crash in the ,north ,atlantic shipping lanes or in some inhabited area4 ,steering commands were being supplied but faulty application of the guidance equations was taking the vehicle far off course4 ,finally1 at #d3bf4af a4m41 after #bic seconds of flight and with just #f seconds left before separation of the ,atlas and ,agena--after which the launch vehicle could not be destroyed--a ,range ,safety officer hit the 8destruct0 button4 ,a flash of light illuminated the sky and the choppy ,atlantic waters were awash with the glowing death of a space probe4 ,even as it fluttered down to the sea1 however1 the radio transponder of the shattered ,mariner ,i continued to transmit for #a minute and #d seconds after the destroy command had been sent4 ,mariner ,i did not succumb easily4 ,,mariner ,,ii3 ,a ,,roll ,,before ,,parking ,ever since ,mariner ,,ii had arrived at the ,cape on ,june #d1 test teams of all organizations had labored day and night to prepare the spacecraft for launch4 ,the end of their efforts culminated after some #fij hours of test time1 both in ,california and in ,florida4 ,thirty-five days after ,mariner ,i met its explosive end1 the first countdown on ,mariner ,,ii was underway4 ,at #f3dc p4m41 ,,est1 ,august #be1 #aifb1 time was picked up4 ,the countdown did not proceed far1 however4 ,the ,atlas crew asked for a hold at ,t minus #bje minutes 7#h3ci p4m47 because of stray voltages in the command destruct system caused by a defective ,agena battery4 ,after considerable delay1 the launch effort was scrubbed at #aj3jf p4m4 ,illustration3 ,two assembly operations and system checkouts are performed separated by a trip to the pad to verify compatibility with the launch vehicle ,illustration3 ,a complete electronic checkout station in the hangar supports the spacecraft to ensure operability ,illustration3 ,mariner takes form as the solar panels are attached and the final hangar checkout operations are performed before the launch4 ,illustration3 ,wrapped in a dust cover1 the spacecraft is transferred from ,hangar ,,ae at ,,amr to the explosive safe area for further tests4 ,illustration3 ,inside the bunker-like explosive safe area1 the powerful midcourse maneuver rocket engine is installed in the center of the spacecraft4 ,illustration3 ,final assembly and inspection complete1 ,mariner is 8canned0 in the nose shroud that will protect it through the ,earth's atmosphere and into space4 ,illustration3 ,at the pad1 the shrouded spacecraft is lifted past the ,atlas 444 ,illustration3 444 and the ,agena4 ,illustration3 ,twelfth floor3 ,mariner reaches its mating level4 ,illustration3 ,the spacecraft is eased over to the top of the ,agena 444 ,illustration3 444 and carefully mated to it4 ,the second launch attempt started at #f3cg p4m41 ,august #bf1 with the ,atlas-,agena ,b and ,mariner ,,ii ready on the pad4 ,at #i3eb p4m41 ,t minus #ajj minutes1 a #dj-minute hold was called to replace the ,atlas main battery4 ,by #aj3cg1 with #ie minutes to launch1 all spacecraft systems were ready to go4 ,a routine hold at ,t minus #fj minutes was extended beyond #cj minutes in order to verify the spacecraft battery life expectation4 ,at #aa3dh p4m41 with the count standing at ,t minus #ee minutes1 the spacecraft1 the vehicles1 the ,range1 and the ,,dsif were all given the green light4 ,when good launching weather was reported at #ab3ah a4m41 ,august #bg1 just #be minutes from liftoff1 a cautious optimism began to mount in the blockhouse and among the tired crews4 ,but the tension began to build again4 ,the second prescheduled hold at ,t minus #e minutes was extended beyond a half-hour when the radio guidance system had difficulty with ground station power4 ,counting was 8picked up0 and the clock continued to move down to #fj seconds before liftoff4 ,suddenly1 the radio guidance system was in trouble again4 ,fluctuations showed in its rate beacon signals1 and another hold was called4 ,still another hold for the same reason followed at ,t minus #ej seconds4 ,this time1 at #a3cj a4m41 the count was set back to ,t minus #e minutes4 ,one further crisis developed during this hold--only #c minutes of pre-launch life remained in ,atlas' main battery4 ,a quick decision was made to hold the switchover to missile power until ,t minus #fj seconds to help conserve the life of the battery4 ,at #a3dh a4m41 the count was resumed again at ,t minus #e minutes4 ,the long seconds began to drag4 ,finally1 the ,convair test director pressed the fire button4 ,out on the launch pad1 the ,atlas engines ignited with a white puff and began to strain against the retaining bolts as #cfj1jjj pounds of thrust began to build up4 ,in a holocaust of noise and flame1 the ,atlas was released and lifted off the launch pad on a bearing of #ajf4h degrees at exactly #a hour1 #ec minutes1 #ac4ibg seconds in the morning of ,august #bg1 #aifb4 ,mariner ,,ii was on its way to listen to the music of the spheres4 ,as the launch vehicle roared up into the night sky1 the ,,jpl ,launch ,checkout ,station 7,,dsif ,o7 tracked the spacecraft until ,mariner disappeared over the horizon4 ,a quick1 preliminary evaluation of spacecraft data showed normal readings and ,atlas seemed to be flying a true course4 ,the ,,amr in-flight data transmission and computational operations were being performed as expected4 ,with liftoff out of the way1 the launch began to look good4 ,after the radio signal from the ground guidance system cut off the engines and the booster section was jettisoned1 the remaining ,atlas forward section1 plus the ,agena and the spacecraft began to roll4 ,however1 it stabilized itself in a normal attitude4 ,although the ,atlas had not gone out of the ,range ,safety restrictions1 it was within just #c degrees of exceeding the ,agena horizon sensor limits1 which would have forced another aborted mission4 ,after the booster separation1 the ,atlas sustainer and vernier engines continued to burn until they were shut off by radio guidance command4 ,shortly thereafter1 spring-loaded bolts ejected the nose-cone shroud which had protected the spacecraft against frictional heating in the atmosphere4 ,simultaneously1 the gyroscopes in the ,agena were started and1 at about #a3eh a4m41 the ,agena and the spacecraft separated from the now-spent ,atlas1 which was retarded by small retro-rockets and drifted back into the atmosphere1 where it was destroyed by friction on reentry4 ,,the ,,parking ,,orbit ,as the ,agena separated from the ,atlas booster vehicle1 it was programmed to pitch down almost #ae degrees1 putting it roughly parallel with the local horizon4 ,then1 following a brief coasting period1 the ,agena engine ignited at #a3eh4ec a4m4 and fired until #b3ja4ab a4m4 ,cut-off occurred at a predetermined value of velocity4 ,both the ,agena and the spacecraft had now reached a speed of approximately #ah1jjj miles per hour and had gone into an ,earth orbit at an altitude of #aaf4ai statute miles4 ,the second stage and the spacecraft were now in a 8parking orbit10 which would allow the vehicle to coast out to a point more favorable than ,cape ,canaveral for blasting off ,mariner for ,venus4 ,during the launch1 ,cape radar had tracked the radar beacon on the ,agena1 losing it on the horizon at #b3jj4ec a4m4 ,radar stations at ,grand ,bahama ,island1 ,san ,salvador1 ,ascension1 the ,twin ,falls ,victory ship1 and ,pretoria 7in ,south ,africa7 continued to track down range4 ,meanwhile1 ,antigua had 8locked on0 and tracked the spacecraft's radio transponder and telemetry from #a3eh to #b3jh a4m4 when it went over the ,antigua horizon4 ,illustration3 ,mariner ,,ii is accelerated to ,earth-escape velocity and out of orbit near ,st4 ,helena4 ,rotation of earth causes flight path to appear to double back to west over ,africa4 ,illustration3 ,the sequence of events in the launch phase of the ,mariner flight to ,venus4 ,,event #a4 ,,liftoff #b4 ,,atlas ,,booster ,,engine ,,cutoff #c4 ,,atlas ,,sustainer ,,engine ,,cutoff #d4 ,,atlas ,,vernier ,,engine ,,cutoff #e4 ,,spacecraft ,,shroud ,,ejection #f4 ,,atlas-,,agena ,b ,,separation #g4 ,,agena ,b ,,first ,,ignition #h4 ,,agena ,b ,,first ,,cutoff #i4 ,,agena ,b ,,second ,,ignition #aj4 ,,agena ,b ,,second ,,cutoff #aa4 ,,spacecraft ,,separation #ab4 ,,initiate ,,agena ,,yaw ,,maneuver #ac4 ,,complete ,,agena ,,yaw ,,maneuver #ad4 ,,expel ,,unused ,,agena ,,propellant ,the second coasting period lasted #af4c minutes1 a time determined by the ground guidance computer and transmitted to the ,agena during the vernier burning period of ,atlas4 ,then1 ,agena restarted its engine and fired for a second time4 ,at the end of this firing period1 both the ,agena and ,mariner1 still attached1 had been injected into a transfer trajectory to ,venus at a velocity exceeding that required to escape from the ,earth's gravity4 ,the actual injection into space occurred at #bf minutes #c4jh seconds after liftoff from the ,cape 7#b3ai4ai a4m41 ,,est7 at a point above #ad4hgc degrees south latitude and #b4jjg degrees west longitude4 ,thus1 ,mariner made the break for ,venus about #cfj miles northeast of ,st4 ,helena1 #b1ejj miles east of the ,brazilian coast1 and about #ijj miles west of ,angola on the west ,african shore4 ,during injection1 the vehicle was being tracked by ,ascension1 telemetry ship ,twin ,falls ,victory1 and ,pretoria4 ,telemetry ship ,whiskey secured the spacecraft signal just after injection and tracked until #b3bf a4m4 ,pretoria began its telemetry track at #b3ba and continued to track for almost two hours1 until #d3ai a4m4 ,injection velocity was #g4jg miles per second or #be1dbj miles per hour1 just beyond ,earth-escape speed4 ,the distance at the time of injection from ,canaveral's ,launch ,complex #ab was #d1jha4c miles4 ,the ,agena and ,mariner flew the escape path together for another two minutes after injection before they were separated at #b3ba a4m4 ,agena then performed a #adj-;degree yaw or retro-turn maneuver by expelling unused propellants4 ,the purpose was to prevent the unsterilized ,agena from possibly hitting the planet1 and from following ,mariner too closely and perhaps disturbing its instruments4 ,now1 ,mariner ,,ii was flying alone and clear4 ,ahead lay a journey of #aji days and more than #ahj million miles4 ,,orientation ,,and ,,midcourse ,,maneuver ,as ,mariner ,,ii headed into space1 the ,deep ,space ,instrumentation ,facility 7,,dsif7 network began to track the spacecraft4 ,at #b3bc4ei a4m41 ,,dsif #e at ,johannesburg1 aided by the ,mobile ,tracking ,station1 installed in vans in the vicinity1 was 8looking0 at the spacecraft1 just four minutes after injection4 ,johannesburg was able to track ,mariner until #d3jd p4m4 because1 as the trajectory took ,mariner almost radially away from the ,earth1 our planet began in effect to turn away from under the spacecraft4 ,on an ,earth map1 because of its course and the rotation of the ,earth1 ,mariner ,,ii appeared to describe a great arc over the ,indian ,ocean far to the west of ,australia1 then to turn north and west and to proceed straight west over south-central ,africa1 across the ,atlantic1 and over the ,amazon ,basin of northern ,south ,america4 ,johannesburg finally lost track at a point over the middle of ,south ,america4 ,while swinging over the ,indian ,ocean on its first pass1 the spacecraft was acquired by ,woomera's ,,dsif #d at #b3db4cj a4m41 and tracked until #h3jh a4m41 when ,mariner was passing just to the north of ,madagascar on a westerly course4 ,goldstone did not acquire the spacecraft until it was approaching the east coast of ,south ,america at #c3ab p4m41 ,august #bg4 ,with ,mariner slowly tumbling in free space1 it was now necessary to initiate a series of events to place the spacecraft in the proper flight position4 ,at #b3bg a4m41 #dd minutes after launch1 the ,mariner ,central ,computer and ,sequencer 7,,cc,s7 on board the spacecraft issued a command for explosively activated pin pullers to release the solar panels and the radiometer dish from their launch-secured positions4 ,at #b3ec1 #fj minutes after liftoff1 the attitude control system was turned on and the ,sun orientation sequence began with the extension of the directional antenna to a preset angle of #gb degrees4 ,illustration3 ,mariner ,,ii was launched while ,venus was far behind the ,earth4 ,during the #aji-;day flight1 ,venus overtook and passed the ,earth4 ,it rendezvoused with the spacecraft at a point about #cf1jjj1jjj miles from the ,earth4 ,illustration3 ,during the midcourse maneuver1 the trajectory of ,mariner ,,ii was corrected so that the spacecraft would approach within #ba1eih miles of ,venus4 ,,roll ,,maneuver ,,antenna ,,up ,,pitch ,,maneuver ,,motor ,,burn ,,sun ,,reaquisition ,,antenna ,,reposition ,,earth ,,reaquisition ,the ,sun sensors then activated the gas jets and moved the spacecraft about until the roll or long axis was pointed at the ,sun4 ,this maneuver required only #b minutes after the ,,cc,s issued the command4 ,the solar panel power output of #aie watts was somewhat higher than anticipated1 as were the spacecraft temperatures1 which decreased and stabilized six hours after the spacecraft oriented itself on the ,sun4 ,on ,august #bi1 a command from ,johannesburg turned on the cruise scientific experiments1 including all the instruments except the two radiometers4 ,the rate of data transmission was then observed to decrease as planned and the data conditioning system was functioning normally4 ,for seven days1 no attempt was made to orient the spacecraft with respect to the ,earth because the ,earth sensors were too sensitive to operate properly at such a close range4 ,on ,september #c1 the ,,cc,s initiated the ,earth acquisition sequence4 ,the gyroscopes were turned on1 the cruise scientific instruments were temporarily switched off1 and a search for the ,earth began about the roll axis of the spacecraft4 ,during this maneuver1 the long axis of the spacecraft was held steady in a position pointing at the ,sun and the gas jets rolled the spacecraft around this axis until the sensors1 mounted in the directional antenna1 could 8see0 the ,earth4 ,apparently1 the ,earth sensor was already viewing the ,earth because the transmitter output immediately switched from the omni- to the directional antenna1 indicating that no search was necessary4 ,however1 the initial brightness reading from the ,earth sensor was #ch1 an intensity that might be expected if the spacecraft were locked onto the ,moon instead of the ,earth4 ,as a result1 the midcourse maneuver was delayed until verification of ,earth lock was obtained4 ,mariner's injection into the ,venus trajectory yielded a predicted miss of #bcc1jjj miles in front of the planet1 well within the normal miss pattern expected as a result of the launch4 ,because the spacecraft was designed to cross the orbit of ,venus behind the planet and pass between it and the ,sun1 it was necessary to correct the trajectory to an approximate #h1jjj- to #dj1jjj-mile 8fly-by0 so the scientific instruments could operate within their design ranges4 ,after comparison of the actual flight path with that required for a proper near-miss1 the necessary roll1 pitch1 and motor-burn commands were generated by the ,,jpl computers4 ,when1 on ,september #d1 it had been established that the spacecraft was indeed oriented on the ,earth and not the ,moon1 a set of three commands was transmitted to the spacecraft from ,goldstone1 to be stored in the electronic 8memory unit0 until the start command was sent4 ,at #a3cj p4m41 ,,pst1 the first commands were transmitted3 a #i4cc-;degree roll turn1 a #aci4hc-;degree pitch turn1 and a motor-burn command to produce a #fi4e-mile-per-hour velocity change4 ,at #b3ci p4m41 a fourth command was sent to switch from the directional antenna to the omni-antenna4 ,finally1 a command went out instructing the spacecraft to proceed with the now 8memorized0 maneuver program4 ,mariner then turned off the ,earth and ,sun sensors1 moved the directional antenna out of the path of the rocket exhaust stream1 and executed a #i4cc-;degree roll turn in #ea seconds4 ,next1 the pitch turn was completed in #ac minutes1 turning the spacecraft almost completely around so the motor nozzle would point in the correct direction when fired4 ,the spacecraft was stabilized and the roll and pitch turns controlled by gyroscopes1 which signalled the attitude control system the rate of correction for comparison with the already computed values4 ,with the solar panels no longer directly oriented on the ,sun1 the battery began to share the power demand and finally carried the entire load until the spacecraft had again been oriented on the ,sun4 ,at the proper time1 the motor--controlled by the ,,cc,s--ignited and burned for #bg4h seconds1 while the spacecraft's acceleration was compared with the predetermined values by the accelerometer4 ,during this period1 when the gas jets could not operate properly1 the spacecraft was stabilized by movable vanes or rudders in the exhaust of the midcourse motor4 ,the velocity added by the midcourse motor resulted in a decrease of the relative speed of the spacecraft with respect to the ,earth by #ei miles per hour 7from #f1gdh to #f1fhi miles per hour71 while the speed relative to the ,sun increased by #de miles per hour 7from #fj1aag to #fj1afb miles per hour74 ,this apparently paradoxical condition occurred because1 in order to intercept ,venus1 ,mariner had been launched in a direction opposite to the ,earth's course around the ,sun4 ,the midcourse maneuver turned the spacecraft around and slowed its travel away from the ,earth while allowing it to increase its speed around the ,sun in the direction of the ,earth's orbit4 ,gradually1 then1 the spacecraft would begin to fall in toward the ,sun while moving in the same direction as the ,earth1 catching and passing the ,earth on the #feth day and intersecting ,venus' orbit on the #ajith day4 ,at the time of the midcourse maneuver1 the spacecraft was travelling slightly inside the ,earth's orbit by #gj1jjj miles1 and was behind the ,earth by #a1dib1ejj miles4 ,,the ,,long ,,cruise ,after its completion of the midcourse maneuver1 ,mariner reoriented itself on the ,sun in #g minutes and on the ,earth in about #cj minutes4 ,during the midcourse maneuver1 the omnidirectional antenna was used2 now1 with the maneuver completed1 the directional antenna was switched back in for the duration of the mission4 ,ever since the spacecraft had left the parking orbit near the ,earth and been injected into the ,venus trajectory1 the ,space ,flight ,operations ,center back in ,pasadena had been the nerve center of the mission4 ,telemetered data had been coming in from the ,,dsif stations on a #bd-;hour schedule4 ,during the cruise phase1 from ,september #e to ,december #g1 a total of #af orbit computations were made to perfect the planet encounter prediction4 ,on ,december #g1 the first noticeable ,venus-caused effects on ,mariner's trajectory were observed1 causing a definite deviation of the spacecraft's flight path4 ,on ,september #h1 at #ab3ej p4m41 ,,est1 the spacecraft lost its attitude control1 which caused the power serving the scientific instruments to switch off and the gyroscopes to switch on automatically for approximately three minutes1 after which normal operation was resumed4 ,the cause was not apparent but the chances of a strike by some small space object seemed good4 ,as a result of this event1 a significant difference in the apparent brightness reading of the ,earth sensor was noted4 ,this sensor had been causing concern for some time because its readings had decreased to almost zero4 ,further decrease1 if actually caused by the instrument and not by the telemetry sensing elements1 could result in loss of ,earth lock and the failure of radio contact4 ,after the incident of ,september #h1 the ,earth sensor brightness reading increased from #f to #fc1 a normal indication for that day4 ,thereafter1 this measurement decreased in an expected manner as the spacecraft increased its distance from the ,earth4 ,mariner ,,ii was now embarked on the long cruise4 ,on ,september #ab1 the distance from the ,earth was #b1fgh1ifj miles and the spacecraft speed relative to the ,earth was #f1dig miles per hour4 ,mariner was accelerating its speed as the ,sun's gravity began to exert a stronger pull than the ,earth's4 ,on ,october #c1 ,mariner was nearly #f million miles out and moving at #f1hbc miles per hour relative to the ,earth4 ,a total of #ee1fjj1jjj miles had been covered to that point4 ,considerable anxiety had developed at ,,jpl when ,mariner's ,earth sensor reading had fallen off so markedly4 ,this situation was relieved by the unexplained return to normal on ,september #h1 although the day-to-day change in the brightness number was watched closely4 ,the apparent ability of the spacecraft to recover its former performance after the loss of attitude control on ,september #h and again on ,september #bi was an encouraging sign4 ,another disturbing event occurred on ,october #ca1 when the output from one solar panel deteriorated abruptly4 ,the entire power load was thrown on the other panel1 which was then dangerously near its maximum rated output4 ,to alleviate this situation1 the cruise scientific instruments were turned off4 ,a week later1 the malfunctioning panel returned to normal operation and the science instruments were again turned on4 ,although the trouble had cleared temporarily1 it developed again on ,november #ae and never again corrected itself4 ,the diagnosis was a partial short circuit between one string of solar cells and the panel frame1 but by now the spacecraft was close enough to the ,sun so that one panel supplied enough power4 ,by ,october #bd1 the spacecraft was #aj1jcj1jjj miles from the ,earth and was moving at #aj1edg miles per hour relative to the ,earth4 ,the distance from ,venus was now #ba1bff1jjj miles4 ,october #cj was the #feth day of the mission and at #e a4m41 ,,pst1 ,mariner overtook and passed the ,earth at a distance of #aa1ejj1jjj miles4 ,since the spacecraft's direction of travel had1 in effect1 been reversed by the midcourse maneuver1 it had been gaining on the ,earth in the direction of its orbit1 although constantly falling away from the ,earth in the direction of the ,sun4 ,the point of equal distance between the ,earth and ,venus was passed on ,november #f1 when ,mariner was #ac1ijj1jjj miles from both planets and travelling at #ac1hdc miles per hour relative to the ,earth4 ,as ,november wore on1 hope for a successful mission began to mount4 ,using tracking data rather than assumptions of standard midcourse performance1 the ,venus miss distance had now been revised to about #ba1jjj miles and encounter was predicted for ,december #ad4 ,but the ,,dsif tracking crews1 the space flight and computer operators1 and the management staff could not yet relax4 ,the elation following the successful trajectory correction maneuver on ,september #d had given way alternately to discouragement and guarded optimism4 ,four telemetry measurements were lost on ,december #i and never returned to normal4 ,they measured the angle of the antenna hinge1 the fuel tank pressure1 and the nitrogen pressure in the midcourse and attitude control systems4 ,a blown fuse1 designed to protect the data encoder from short circuits in the sensors1 was suspected4 ,however1 these channels could not affect spacecraft operation and ,mariner continued to perform normally4 ,the rising temperatures recorded on the spacecraft were more serious4 ,only the solar panels were displaying expected temperature readings2 some of the others were as much as #ge degrees above the values predicted for ,venus encounter4 ,the heat increase became more rapid after ,november #bj4 ,by ,december #ab1 six of the temperature sensors had reached their upper limits4 ,it was feared that the failure point of the equipment might be exceeded4 ,the ,,cc,s performed without incident until just before encounter1 when1 for the first time1 it failed to yield certain pulses4 ,,jpl engineers were worried about the starting of the encounter sequence1 due the next day1 although they knew that ,earth-based radio could send these commands1 if necessary4 ,on ,december #ab1 with the climax of the mission near1 the spacecraft was #cd1bah1jjj miles from the ,earth1 with a speed away from the ,earth of #ce1gij miles per hour1 a ,sun-relative speed of #hc1ijj miles per hour4 ,only #fce1ebe miles from ,venus at this point1 ,mariner ,,ii was closing fast on the cloud-shrouded planet4 ,but it was a hot spacecraft that was carrying its load of inquisitive instruments to the historic encounter4 ,,encounter ,,and ,,beyond ,on its #ajith day of travel1 ,mariner had approached ,venus in a precarious condition4 ,seven of the over-heated temperature sensors had reached their upper telemetry limits4 ,the ,earth-sensor brightness reading stood at #c 7#j was the nominal threshold7 and was dropping4 ,some #adi watts of power were being consumed out of the #afe watts still available from the crippled solar panels4 ,at ,,jpl's ,space ,flight ,operations ,center1 there was reason to believe that the ailing ,,cc,s might not command the spacecraft into its encounter sequence at the proper time4 ,twelve hours before encounter1 these fears were verified4 ,quickly1 the emergency ,earth-originated command was prepared for transmission4 ,at #e3ce a4m41 ,,pst1 a radio signal went out from ,goldstone's ,echo ,station4 ,thirty-six million miles away1 ,mariner ,,ii responded to the tiny pulse of energy from the ,earth and began its encounter sequence4 ,after ,mariner had 8acknowledged0 receipt of the command from the ,earth1 the spacecraft switched into the encounter sequence as engineering data were turned off and the radiometers began their scanning motion1 taking up-and-down readings across the face of the planet4 ,as throughout the long cruise1 the four experiments monitoring the magnetic fields1 cosmic dust1 charged particles1 and solar plasma experiments continued to operate4 ,illustration3 ,mariner ,,ii approached ,venus from the dark side1 crossed between the planet and the ,sun while making three radiometer scans of the disk4 ,as ,mariner approached ,venus on its night side1 it was travelling about #hh1djj miles per hour with respect to the ,sun4 ,at the point of closest approach1 at #aa3ei4bh a4m41 ,,pst1 the distance from the planet was #ba1eih miles4 ,during encounter with ,venus1 three scans were made3 one on the dark side1 one across the terminator dividing dark and sunlit sides1 and one on the sunlit side4 ,although the scan went slightly beyond the edge of the planet1 the operation proceeded smoothly and good data were received on the ,earth4 ,with encounter completed1 the cruise condition was reestablished by radio command from the ,earth and the spacecraft returned to transmitting engineering data1 together with the continuing readings of the four cruise scientific experiments4 ,after approaching closer to a planet and making more meaningful scientific measurements than any man-made space probe1 ,mariner ,,ii continued on into an orbit around the ,sun4 ,december #bg1 #ac days after ,venus encounter1 marked the perihelion1 or point of ,mariner's closest approach to the ,sun3 #fe1eje1ice miles4 ,the ,sun-related speed was #hi1ddb miles per hour4 ,as ,mariner began to pull away from the ,sun in the following months1 its ,sun-referenced speed would decrease4 ,data were still being received during these final days and the ,earth and ,sun lock were still being maintained4 ,although the antenna hinge angle was no longer being automatically readjusted by the spacecraft1 commands were sent from the ,earth in an attempt to keep the antenna pointed at the ,earth1 even if the ,earth sensor were no longer operating properly4 ,at #b a4m41 ,,est1 ,january #c1 #aifc1 #bj days after passing ,venus1 ,mariner finished transmitting #cj minutes of telemetry data to ,johannesburg and the station shut down its operation4 ,when ,woomera's ,,dsif #d later made a normal search for the spacecraft signal1 it could not be found4 ,goldstone also searched in vain for the spacecraft transmissions1 but apparently ,mariner's voice had at last died1 although the spacecraft would go into an eternal orbit around the ,sun4 ,it was estimated that ,mariner's aphelion 7farthest point out7 in its orbit around the ,sun would occur on ,june #ah1 #aifc1 at a distance of #aac1hac1jhg miles4 ,maximum distance from the ,earth would be #ih1jfc1eii miles on ,march #cj1 #aifc2 closest approach to the ,earth3 #be1gfe1gag miles on ,september #bg1 #aifc4 ,,the ,,record ,,of ,,mariner ,the performance record of ,mariner ,,ii exceeded that of any spacecraft previously launched from ,earth3 --,it performed the first and most distant trajectory-correcting maneuver in deep space1 firing a rocket motor at the greatest distance from the ,earth3 #a1dib1jjj miles 7,september #d1 #aifb74 --,the spacecraft transmitted continuously for four months1 sending back to the ,earth some #ij million bits of information while using only #c watts of transmitted power4 --,useful telemetry measurements were made at another record distance from the ,earth3 #ec4i million miles 7,january #c1 #aifc74 --,mariner ,,ii was the first spacecraft to operate in the immediate vicinity of another planet and return useful scientific information to the ,earth3 approximately #ba1eih miles from ,venus 7,december #ad1 #aifb74 --,measurements were made closest to the ,sun3 #fe4c million miles away 7,december #bg1 #aifb74 --,mariner's communication system operated for the longest continuous period in interplanetary space3 #abi days 7,august #bg1 #aifb1 to ,january #c1 #aifc74 --,mariner achieved the longest continuous operation of a spacecraft attitude-stabilization system in space1 and at a greater distance from the ,earth than any previous spacecraft3 #abi days 7,august #bg1 #aifb1 to ,january #c1 #aifc71 at #ec4i million miles from the ,earth4 ,,chapter #f ,,the ,,tracking ,,network ,thirty-six million miles separated the ,earth from ,venus at encounter4 ,communicating with ,mariner ,,ii and tracking it out to this distance1 and beyond1 represented a tremendous extension of man's ability to probe interplanetary space4 ,the problem involved3 #a4 ,the establishment of the spacecraft's velocity and position relative to the ,earth1 ,venus1 and the ,sun with high precision4 #b4 ,the transmission of commands to activate spacecraft maneuvers4 #c4 ,the reception of readable spacecraft engineering and scientific data from the far-ranging ,mariner4 ,the tracking network had to contend with many radio noise sources3 the noise from the solar system and from extragalactic origins2 noise originating from the ,earth and its atmosphere2 and the inherent interference originating in the receiving equipment4 ,these problems were solved by using advanced high-gain antennas and ultra-stable1 extremely sensitive receiving equipment4 ,,deep ,,space ,,instrumentation ,,facility ,the ,national ,aeronautics and ,space ,administration has constructed a network of deep-space tracking stations for lunar and planetary exploration missions4 ,in order to provide continuous1 #bd-;hour coverage1 three stations were built1 approximately #abj degrees of longitude apart1 around the world3 at ,goldstone in the ,california desert1 near ,johannesburg in ,south ,africa1 and at ,woomera in the south-central ,australian desert4 ,illustration3 ,the three tracking stations of the ,deep ,space ,instrumentation ,facility are located around the world so as to provide continuous flight coverage4 ,these stations are the basic elements of the ,deep ,space ,instrumentation ,facility 7,,dsif74 ,in addition1 a mobile tracking station installed in vans is used near the point of injection of a spacecraft into an ,earth-escape trajectory to assist the permanent stations in finding the spacecraft and to acquire tracking data4 ,the control point for the ,,dsif net is located at ,,jpl in ,pasadena1 ,california 7see ,table #a74 ,the ,jet ,propulsion ,laboratory has the responsibility for the technical direction of the entire ,,dsif net and operates the ,goldstone facilities with assistance from the ,bendix ,corporation as a subcontractor4 ,the overseas stations are staffed and operated by agencies of the ,republic of ,south ,africa and the ,commonwealth of ,australia4 ,the ,,dsif net tracks the position and velocity of ,u4,s4 deep-space probes1 issues commands to direct the spacecraft in flight1 receives engineering and scientific data from the probes1 and automatically relays the data to ,,jpl in ,pasadena1 where it is processed by computers and interpreted4 7,in the tracking operation1 a signal is transmitted to the spacecraft1 where it is received and processed in a transponder1 which then sends the signal back to the ,earth4 ,the change in frequency1 known as the doppler effect1 involved in this operation enables engineers to determine the velocity at which the spacecraft is moving47 ,table #a4 ,deep ,space ,instrumentation ,facility ,stations ,station ,location ,equipment ,functions ,,dsif #a 7,mobile ,near point of #aj-;ft antenna ,fast tracking ,tracking injection of #be-w1 #hij-mc for acquisition ,station7 spacecraft into transmitter of spacecraft ,earth-escape trajectory ,goldstone3 ,california ,pioneer ,site #he-;ft ,reception of 7,,dsif #b7 polar-mount telemetry antenna2 ,tracking ,cassegrain spacecraft feed2 maser and parametric amplifier ,echo ,site #he-;ft ,transmission of 7,,dsif #c7 polar-mount commands antenna2 ,tracking parametric spacecraft amplifier ,stand-by #aj-kw1 #hij-mc reception transmitter ,venus ,site #he-;ft ,advanced radar radar-type astronomy antenna ,communications research ,,dsif #d ,woomera1 #he-;ft ,reception of ,australia polar-mount telemetry antenna2 ,tracking parametric spacecraft amplifier ,,dsif #e ,johannesburg1 #he-;ft ,reception of ,south ,africa polar-mount telemetry antenna2 ,tracking parametric spacecraft amplifier ,transmission of #aj-kw1 #hij-mc commands transmitter ,the stations are equipped with receiving and tracking instruments so sensitive that engineers estimate that they can detect radio-frequency energy equivalent to that radiated by a #a-watt light bulb at a distance of approximately #ge to #hj million miles4 ,such energy received at the antenna would measure about #j4jjjjjjjjjjjjjjjjjjjb watt 7#b #aj74 ,the amount of power received at the antenna during ,mariner's encounter with ,venus has been calculated at about #j4jjjjjjjjjjjjjjjjja of a watt 7#a #aj74 ,if a #ajj percent efficient storage battery were charged with this amount of energy for some #cj billion years1 the battery would then have stored enough energy to light an ordinary #a-watt flashlight bulb for about #a second only4 ,furthermore1 ,goldstone engineers estimate that1 if ,mariner ,,ii had continued to function in all its systems and to point its directional antenna at the ,earth1 useful telemetry data could have been obtained by the ,,dsif stations out to about #aej to #bjj million miles1 and tracking data could have been secured from as far as #cjj to #djj million miles4 ,construction of the ,,dsif net was begun in #aieh4 ,the ,goldstone station was ready for the ,pioneer ,,iii mission in ,december of that year4 ,in ,march1 #aiei1 ,pioneer ,,iv was successfully tracked beyond the ,moon4 ,later in #aiei1 ,pioneer ,v was tracked out to over #c million miles4 ,goldstone participated in the #aifj ,project ,echo communication satellite experiments and the entire net was used in the ,ranger lunar missions of #aifa-aifb4 ,the ,goldstone station performed ,venus radar experiments in #aifa and #aifb to determine the astronomical unit more precisely and to study the rotation rate and surface characteristics of the planet4 ,following the launch of ,mariner ,,ii on ,august #bg1 #aifb1 the full ,,dsif net provided #bd-;hour-per-day tracking coverage throughout the mission except for a few days during the cruise phase4 ,the net remained on the full-coverage schedule through the period of ,venus encounter on ,december #ad4 ,,the ,,goldstone ,,complex ,the tracking antennas clustered in a #g-mile radius near ,goldstone ,dry ,lake1 ,california1 are the central complex of the ,,dsif net4 ,three tracking sites are included in the ,goldstone ,station3 ,pioneer ,site 7,,dsif #b71 ,echo ,site 7,,dsif #c71 and ,venus ,site4 ,the ,venus ,site is used for advanced radar astronomy1 communication research experiments1 and radio development2 it took no direct part in the ,mariner spacecraft tracking operations1 but was used for the ,venus radar experiments4 ,pioneer ,site has an #he-;foot-diameter parabolic reflector antenna and the necessary radio tracking1 receiving1 and data recording equipment4 ,the antenna can be pointed to within better than #j4jb of a degree4 ,the antenna has one 7hour-angle7 axis parallel to the polar axis of the ,earth1 and the other 7declination7 axis perpendicular to the polar axis and parallel to the equatorial plane of the ,earth4 ,this 8polar-mount0 feature permits tracking on only one axis without moving the other4 ,the antenna weighs about #bdj tons but can be rotated easily at a maximum rate of #a degree per second4 ,the minimum tracking rate or antenna swing 7#j4bejfhfdhf degree per minute7 is equal to the rotation rate of the ,earth4 ,two drive motors working simultaneously but at different speeds provide an antibacklash safety factor4 ,the antenna can operate safely in high winds4 ,the ,pioneer antenna has a type of feed system 7,cassegrain7 that is essentially similar to that used in many large reflector telescopes4 ,a convex cone is mounted at the center of the main dish4 ,a received signal is gathered by the main dish and the cone1 reflected to a subreflector on a quadripod1 where the energy is concentrated in a narrow beam and reflected back to the feed collector point on the main dish4 ,the ,cassegrain feed system lowers the noise picked up by the antenna by reducing interference from the back of the antenna1 and permits more convenient location of components4 ,the receiving system at ,pioneer ,site is also equipped with a low-noise1 extremely sensitive installation combining a parametric amplifier and a maser4 ,the parametric amplifier is a device that is 8pumped0 or excited by microwave energy in such a way that1 when an incoming signal is at its maximum1 the effect is such that the 8pumped-in0 energy augments the original strength of the incoming signal4 ,at the same time1 the parametric amplifier reduces the receiving system's own electronic noise to such a point that the spacecraft can be tracked twice as far as before4 ,the maser uses a synthetic ruby mixed with chromium and is maintained at the temperature of liquid helium--about #d4g degrees ,k or -#dej degrees ,f 7just above absolute zero7--and when 8pumped0 with a microwave field1 the molecular energy levels of the maser material are redistributed so as to again improve the signal amplification while lowering the system noise4 ,the maser doubles the tracking capability of the system with a parametric amplifier1 and quadruples the capability of the receiver alone4 ,the antenna output at ,pioneer is a wide-band telemetering channel4 ,in addition1 the antenna can be aimed automatically1 using its own 8error signals40 ,at both the ,pioneer and ,echo sites at ,goldstone1 however1 the antenna is pointed by a punched tape prepared by a special-purpose computer at ,,jpl and transmitted to ,goldstone by teletype4 ,pioneer ,site has a highly sensitive receiver designed to receive a continuous wave signal in a narrow frequency band in the #ifj-megacycle range4 ,the site has equipment for recording tracking data for use by computers in determining accurate spacecraft position and velocity4 ,the instrumentation equipment also includes electronic signal processing devices1 magnetic-tape recorders1 oscillographs1 and other supplementary receiving equipment4 ,the telemetered data can be decommutated 7recovered from a signal shared by several measurements on a time basis71 encoded1 and transmitted by teletype in real time 7as received from the spacecraft7 to ,,jpl4 ,echo ,site is the primary installation in the ,goldstone complex and has antenna and instrumentation facilities identical to those at ,pioneer1 except that there is no maser amplifier and a simpler feed system is used instead of the ,cassegrain4 ,however1 ,echo was used as a transmitting facility and only as a stand-by receiving station during the ,mariner mission4 ,echo has a #aj-kilowatt1 #hij-megacycle transmitter which was utilized for sending commands to the ,mariner spacecraft4 ,in addition1 the site has an 8atomic clock0 frequency standard1 based on the atomic vibrations of rhubidium1 which permits high-precision measurements of the radial velocity of the spacecraft4 ,a unit in the ,echo system provides for 8readback0 and 8confirmation0 by the spacecraft of commands transmitted to it4 ,in a sense1 the spacecraft acknowledges receipt of the commands before executing them4 ,walter ,e4 ,larkin manages the ,goldstone ,station for ,,jpl4 ,,the ,,woomera ,,station ,the ,woomera1 ,australia1 ,station 7,,dsif #d71 managed by ,william ,mettyear for the ,australian ,department of ,supply1 has essentially the same antenna and tracking capabilities as ,goldstone ,echo ,site1 but it has no provisions for commanding the spacecraft4 ,a small transmitter is used for tracking purposes only4 ,the station is staffed and operated by the ,australian ,department of ,supply4 ,illustration3 ,the ,mobile ,tracking ,station 7,,dsif #a7 follows the fast-moving spacecraft during its first low-altitude pass over ,south ,africa4 ,illustration3 ,station #e of the ,,dsif is located near ,johannesburg in ,south ,africa4 ,illustration3 ,,dsif #d1 at ,woomera1 dominates the landscape in ,australia's 8outback40 ,woomera1 like ,johannesburg1 is capable of receiving tracking 7position and velocity7 data and telemetered information for real-time transmission by radio teletype to ,,jpl4 ,,the ,,johannesburg ,,station ,,dsif #e is located just outside ,johannesburg in the ,republic of ,south ,africa4 ,this station is staffed by the ,national ,institute of ,telecommunications ,research 7,,nitr7 of the ,south ,african ,council for ,scientific and ,industrial ,research and managed by ,douglas ,hogg4 ,the antenna and receiving equipment are identical to the ,goldstone ,echo ,site installation except for minor details4 ,the station has both transmitting and receiving capability and can send commands to the spacecraft4 ,recorded tracking and telemetered data are transmitted in real time to ,,jpl by radio teletype4 ,,mobile ,,tracking ,,station ,the ,mobile ,tracking ,station 7,,dsif #a7 is a movable installation designed for emplacement near the point of injection of a space probe to assist the permanent stations in early acquisition of the spacecraft4 ,this station is necessary because at this point the spacecraft is relatively low in altitude and consequently appears to move very fast across the sky4 ,the ,mobile ,tracking ,station has a fast-tracking antenna for use under these conditions4 ,,dsif #a was located near the ,south ,african station for ,mariner ,,ii4 ,it has a #aj-;foot parabolic antenna capable of tracking at a #aj-;degree-per-second rate4 ,a #be-watt1 #hij-megacycle transmitter is used for obtaining tracking information4 ,a diplexer permits simultaneous transmission and reception on the same antenna without interference4 ,the equipment is installed in mobile vans so that the station can be operated in remote areas4 ,the antenna is enclosed in a plastic dome and is mounted on a modified radar pedestal4 ,the radome is inflatable with air and protects the antenna from wind and weather conditions4 ,these stations of the ,,dsif tracked ,mariner ,,ii in flight and sent commands to the spacecraft for the execution of maneuvers4 ,the telemetry data received from the spacecraft during the #abi days of its mission were recorded and transmitted to ,,jpl1 where the information was processed and reduced by the computers of the space flight operations complex4 ,,chapter #g ,,thirteen ,,million ,,words ,the task of receiving1 relaying1 processing1 and interpreting the data coming in simultaneously on a twenty-four-hour basis for several months from the several scientific and many engineering sources of the ,mariner spacecraft was of truly monumental proportions4 ,this activity involved five ,,dsif tracking stations scattered around the world1 a communication network1 two computing stations and auxiliary facilities1 and some #djj personnel over a four-month period4 ,although the ,mariner scientific information could be stored and subsequently processed at a later 7non-real7 time1 it was necessary to make tracking and position data available almost as soon as it was received 7in real time7 so that the midcourse maneuver might be computed and transmitted to the spacecraft1 and to further perfect the predicted trajectory and arrival time at ,venus4 ,the engineering performance of the many spacecraft subsystems was also of vital concern4 ,inaccurate operation in any of several areas could endanger the success of the entire mission4 ,the performance of the attitude control system1 the ,earth and ,sun sensors1 the power system1 and communications were all of critical importance4 ,corrective action was possible in certain subsystems where trouble could be predicted from the data or where limited breakdown had occurred4 ,to integrate all the varied activities necessary to accomplish the mission objectives1 an organization was formed within ,,jpl to coordinate the ,,dsif1 the communication network1 the work of engineering and scientific advisory panels1 and the computer facilities required to evaluate the data4 ,this organization was known as the ,space ,flight ,operations ,complex4 ,for operational purposes only1 it included the ,space ,flight ,operations ,center1 a ,communication ,center1 and a ,central ,computing ,facility 7,,ccf74 ,the ,,dsif was responsive to the requirements of the organization1 but was not an integral part of it4 ,a space flight operations director was responsible for integrating these many functions into a world-wide ,mariner space-flight organization4 ,it was an exhausting #aji-;day task1 one that would severely tax all the resources of ,,jpl in terms of know-how1 qualified personnel1 time1 and equipment before ,mariner completed its encounter with ,venus4 ,,communication ,,control ,the ,communication ,center at ,,jpl in ,pasadena was one of the most active areas during the many days and nights of the ,mariner ,,ii mission4 ,all of the teletype and radio lines from the ,cape1 ,south ,africa1 ,australia1 and ,goldstone terminated in this ,center4 ,a high-speed data line bypassed the ,communication ,center1 linking ,goldstone directly with the ,central ,computing ,facility for quick1 real-time computer processing of vital flight information4 ,from the ,communication ,center1 the teletype data and voice circuits were connected to the several areas within ,,jpl where the mission-control activities were centered1 and where the data output was being studied4 ,the ,communication ,center was equipped with teletype paper-page printers and paper-tape hole reperforators1 which received and transmitted data-word and number groups4 ,the teletype lines terminating at the ,center included circuits from ,goldstone1 ,south ,africa1 ,australia1 and ,cape ,canaveral4 ,there were three lines to ,goldstone for full-time1 one-way data transmission4 ,duplex 7simultaneous two-way7 transmission was available to ,woomera and ,south ,africa on a full-time basis4 ,in each case1 a secondary circuit was provided to the overseas sites for use during critical periods and in case the primary radio-teletype circuits had transmission difficulties4 ,these secondary circuits used different radio transmission paths in order to reduce the chance of complete loss of contact for any extended period of time4 ,illustration3 ,radio signals from ,mariner are received on #he-;ft4 antenna4 ,illustration3 ,the highly sensitive receiver 7shown under test7 is located in the control room of the station4 ,illustration3 ,in ,goldstone control room1 ,,dsif personnel await confirmation that spacecraft has begun to scan the planet ,venus4 ,illustration3 ,from ,,dsif stations1 the data are teletyped in coded format to ,pasadena4 ,z ,,zsqsgsgkgkxrgoqos ,,dnq ,,xzarzxavaqqva ,,xxdrdz ,,qsgigkgkxrgoqox ,,dxq ,,xzaizxavqqkdz ,,xxdrdddrz ,,dxq ,,xzaizazvaqqzdzxxdlkkdra ,z ,,dsqsgigggqxrdn ,g ,,xxdrzsdra ,z ,,dsqsgigggqxrglzox ,,dxq ,,xzaizazv ,,qsgigggqxrglzox ,,dxq ,,xzaizgavaqqsxzxxdrdzdra ,,dxq ,,xqaizgavqqkva ,,xxdrdzdrangdssqsgigggqxrdi ,z ,,xxdrdddrzlq ,,zsqsgiggggxrgvzoa ,,dnq ,,xzarzgav ,,qsgiggggxrgvqoa ,,dnq ,,xzarzgavqkzzazxxdrzddra ,,dnq ,,xzarzazvakddgzxxdrdadizla ,,dsqsgiggggxrgz ,,szxxdrdddrxos ,,dsqsqiggggxrddzoa ,,dnq ,,xzarzxav ,,qsgsggggxrdsqog ,,dxq ,,xzarzxavakdzdzxxdrdldra ,,dxq ,,xzarzxazzkzzdzxxdlkadra ,z ,,dsqsgiggggxrgx ,,gzxxdrzxdrz ,z ,,dsqsaqggggxrdazog ,,dxq ,,xzaizazv ,,drdxdra ,z ,,dsqsgiggggxrdgsog ,,dxq ,,xzaizazvqkzs ,,ogggxrdgaog ,,dxq ,,xzaizazvqkzva ,,xxdrdzdrangdss ,,xzaizxazzkzzd ,,xxdrdlzdzha ,,dsqsgiggggxrdqaoq ,,dlkadrkhq ,,zsqsgiggggxrdkzoq ,,dxq ,,xzavzaavqkzz ,,ggggxrs ,,zoq ,,dxq ,,xzaizazvqkzdg ,,xxdrdsdiz ,a ,,zs ,,xzaizazvqqksx ,,xxdrdddrzns ,,zsqsgiggggxrsoaoq ,,drdzdrangdssqsaqggggxrsoaok ,,dnq ,,xzavzaavqqkz ,,ggggxrsnzok ,,dnq ,,xzaizazzsqqzszxxdlkadra ,z ,,ds ,,xzaizgavqqkzg ,,xxdrzxdrz ,z ,,dsqsaqggggxrslaok ,,drdsdrz ,z ,,dsqsaqggggxrslaok ,,dnq ,,xzaizazzzqks ,,ggggxrslaok ,,dnq ,,xzaizazzzqkva ,,xxdrdzdrangdss ,,xrsizhz ,,dxq ,,xzaizazzzqkqqzxxdrdndrznq ,,dsqsgs ,,zxazsqqzxzxxdlkqdrsqs ,,zsqsgigggqxrsvahz ,,dxq ,illustration3 ,messages are received and routed at the ,,jpl ,communications ,center4 ,illustration3 ,data are routed to the digital computer at ,,jpl4 ,illustration3 ,printout data are made available to experimenters4 ,illustration3 ,spacecraft status is posted in ,operations ,center4 ,the ,mobile ,tracking ,station in ,south ,africa used the ,johannesburg communication facilities4 ,two one-way circuits for testing and control purposes were open to ,cape ,canaveral from a month before until after the spacecraft was launched4 ,lines from the ,communication ,center to the ,space ,flight ,operations ,center at ,,jpl terminated in page printers and reperforators in several locations4 ,voice circuits connected all of the stations with ,operations ,center through the ,communication ,center4 ,long-distance radio telephone calls were placed to ,south ,africa to establish contact before the launch sequence was started4 ,woomera used the ,project ,mercury voice circuits to the ,united ,states during launch and for three days after4 ,,the ,,operations ,,center ,the actual nerve center of the ,mariner operation was the ,space ,flight ,operations ,center 7,,sfoc7 at ,pasadena4 ,here1 technical and scientific advisory panels reported to the ,project ,manager and the ,mariner ,test ,director on the performance of the spacecraft in flight1 analyzed trajectories1 calculated the commands for the midcourse trajectory correction1 and studied the scientific aspects of the mission4 ,these panels were a ,spacecraft ,data ,analysis ,team1 a ,scientific ,data ,group1 an ,orbit ,determination ,group1 a ,tracking ,data ,analysis ,group1 and a ,midcourse ,command ,group4 ,the ,spacecraft ,data ,analysis ,team analyzed the engineering data transmitted from the spacecraft to evaluate the performance of the subsystems in flight4 ,the ,team was composed of one or more of the engineers responsible for each of the spacecraft subsystems1 and a chairman4 ,the ,science ,data ,group was composed of the project scientist and certain other scientists associated with the experiments on board the spacecraft4 ,this ,group evaluated the data from the scientific experiments while ,mariner was in flight and advised the ,test ,director on the scientific status of the mission4 ,the ,science ,data ,group was on continuous duty until #dh hours after launch1 and at other times during the mission4 ,during encounter with ,venus1 the ,group was also in contact with the scientific experimenters from other participating organizations who were working with ,,jpl4 ,illustration3 ,closed circuit television monitors are used for instant surveillance of the internal activities of the ,operations ,center4 ,a ,tracking ,data ,analysis ,group analyzed the tracking data to be used in orbit determination4 ,they also assessed the performance of the ,,dsif facilities and equipment used to obtain the data4 ,the ,orbit ,determination ,group used the tracking data to produce estimates of the actual spacecraft trajectory1 and to compute the spacecraft path with respect to the ,earth1 ,venus1 and the ,sun4 ,these calculations were made once each day before the midcourse maneuver1 once a week during the cruise phase1 and daily during and immediately after the planet encounter4 ,the ,operations ,center was equipped with lighted boards on which the progress of the mission was displayed4 ,this information included trajectory data1 spacecraft performance1 temperature and pressure readings1 and other data telemetered from the spacecraft subsystems4 ,closed-circuit television was used for coordinating the activities of the ,,sfoc4 ,operating personnel could use television monitors in four consoles which were linked to six fixed cameras viewing teletype page printers4 ,the entire ,operations ,room could be kept under surveillance by the ,project ,manager1 the ,test ,director1 or the ,,dsif ,operations ,manager1 using cameras controlled in 8pan10 8tilt10 and 8zoom40 ,,central ,,computing ,,facility ,during the ,mariner ,,ii mission1 the ,,jpl ,central ,computing ,facility 7,,ccf7 processed approximately #ac4a million data words1 or over #ij million binary bits of computer data4 7,binary bit a discrete unit of information intelligible to a digital computer4 ,one data word #g binary bits47 ,in the four-month operation1 about #ajj1jjj tracking and telemetering data cards were received and processed1 yielding over #a4b million computer pages of tabulated1 processed1 and analyzed data for evaluation by the engineers and scientists4 ,approximately #a1jjj miles of magnetic tape were used in the #a1jef rolls recorded by the ,,dsif4 ,the ,central ,computing ,facility processed and reduced tracking and telemetry data from the spacecraft1 as recorded and relayed by the stations of the ,,dsif4 ,the tracking information was the basis for orbital calculations and command decisions4 ,after delivery of telemetry data on magnetic tapes by the ,,dsif1 the ,,ccf stored the data for later reduction and analysis4 ,where telemetry data were being processed in real or near-real time1 certain critical engineering and scientific functions were programmed to print-out an 8alarm0 reading when selected measurements in the data were outside specified limits4 ,the ,,ccf consists of three stations at ,,jpl3 ,station ,c1 the primary computing facility2 ,station ,d1 the secondary installation2 and the ,telemetry ,processing ,station 7,,tps74 ,station ,c was the principal installation for processing both tracking and telemetry data received from the ,,dsif tracking stations1 both in real and non-real time4 ,the ,station was equipped with a high-speed1 general-purpose digital computer with a #cb1afh-word memory and two input-output channels1 each able to handle #f tape units4 ,the associated card-handling equipment was also available4 ,tape translators or converters were provided for converting teletype data and other digital information into magnetic tape format for computer input4 ,the teletype-to-tape unit operated at a rate of #cjj characters per second4 ,a smaller computer acted as a satellite of the larger unit1 performing bookkeeping and such related functions as card punching1 card reading1 and listing4 ,a high-speed unit microfilmed magnetic-tape printout was received from the large computer4 ,it provided 8quick-look0 copy within #cj minutes of processing the raw data4 ,various paper-tape-to-card and card-to-paper-tape converters were used to eliminate human error in converting teletype data tape to computer cards4 ,station ,c also utilized another computer as a real-time monitor and to prepare a magnetic tape file of all telemetered measurements for input to the large computer4 ,station ,d was the secondary or backup computational facility1 primarily intended for use in case of equipment failure in ,station ,c4 ,during certain critical phases of the ,mariner mission--launch1 orbit determination1 midcourse maneuver--this facility paralleled the operations in ,station ,c4 ,station ,d is equipped with three computers and various card-to-tape converters and teletype equipment4 ,the ,telemetry ,processing ,station received and processed all demodulated data 7that recovered from the radio carrier7 on magnetic tapes recorded at the ,,dsif stations4 ,the ,,tps output was digital magnetic tapes suitable for computer entry4 ,the ,,tps equipment included ,,fm discriminators1 a code translator1 a device for converting data from analog to digital form1 and magnetic-tape recorders4 ,basically1 the equipment accepted the digital outputs from the tape units1 the analog-to-digital converter1 and the code translator and put them in digital tape format for the computer input4 ,as the launch operation started on ,august #bg1 the powered-flight portion of the space trajectories program was run at launch minus #e minutes 7,l minus #e7 and was repeated several times because of holds at ,,amr4 ,the orbit determination program was run at lift-off to calculate the first orbit predictions used for aiding the ,,dsif in finding the spacecraft in flight4 ,during the #ab hours following launch1 both ,c and ,d ,stations performed parallel computations on tracking data4 ,station ,d discontinued space flight operations at ,l plus #ab hours and resumed at the beginning of the midcourse maneuver phase4 ,tracking data processing and midcourse maneuver studies were conducted daily until the midcourse maneuver was performed at ,l plus eight days4 ,for the following #ig days1 tracking data were processed once each week for orbit determination4 ,starting three days before the encounter1 tracking data were processed daily until the beginning of the encounter phase4 ,tracking data processing was conducted in near-real time throughout encounter day1 and daily for two days thereafter4 ,for these three days1 tracking data were handled in ,station ,d in order to permit exclusive use of ,station ,c for telemetry data processing and analysis4 ,after this three-day period1 including the encounter1 ,station ,c processed the tracking data every sixth day until the mission terminated on ,l plus #abi days4 ,telemetry data were processed in a different manner4 ,following the launch1 ,,dsif ,station #e at ,south ,africa received the telemetry signal first1 demodulated it1 and put it in the proper format for teletype transmission to ,,jpl4 ,the other ,,dsif stations followed in sequence as the spacecraft was heard in other parts of the world4 ,for two days after launch1 the computers processed telemetry data as required by the ,spacecraft ,data ,analysis ,team4 ,during those periods when the large computer was processing tracking data1 a secondary unit supplied quick-look data in near-real time4 ,when ,goldstone was listening to the spacecraft1 quick-look data were processed in real time1 using the high-speed data line direct to the ,central ,computing ,facility4 ,for the #ajf days that ,mariner was actually in ,mode ,,ii 7cruise71 the telemetry data were processed twenty-four hours a day1 seven days a week4 ,data were presented to the engineering and science analysis teams in quick-look format every three hours1 except for short maintenance interruptions1 one computer failure1 and a major modification requiring three days1 when a back-up data process mode of operation was used4 ,the large computer performed full processing and analysis of engineering and science data seven days a week from launch until the ,venus encounter4 ,on encounter day1 the secondary ,station ,c computer processed telemetry data from the high-speed ,goldstone line4 ,data on magnetic tapes produced by the computer were processed and analyzed by the large unit in near-real time every #cj minutes4 ,the computer processing and delivery time during this operation varied from #d to #g minutes4 ,,chapter #h ,,the ,,scientific ,,experiments ,after a year of concentrated effort1 in which the resources of ,,nasa1 the ,jet ,propulsion ,laboratory1 and ,american science and industry had been marshalled1 ,mariner ,,ii had probed secrets of the solar system some billions of years old4 ,scientists and engineers had studied the miles of data processed in ,california from the tapes recorded at the five ,,dsif tracking stations around the world4 ,two and a half months of careful analysis and evaluation yielded a revised estimate of ,venus and of the phenomena of space4 ,as a result1 the dynamics of the solar system were revealed in better perspective and the shrouded planet stood partially unmasked4 ,when the ,mariner data were correlated with the data gathered by ,,jpl radar experiments at ,goldstone in #aifa and #aifb1 the relationships between the ,earth1 ,venus1 and the ,sun became far clearer than ever before4 ,two experiments were carried on the spacecraft for a close-up investigation of ,venus' atmosphere and temperature characteristics--a microwave radiometer and an infrared radiometer4 ,they were designed to operate during the approximate #ce-minute encounter period and at a distance varying from about #aj1bjj miles to #di1bjj miles from the center of the planet4#b ,illustration3 ,cosmic dust detector4 ,illustration3 ,solar plasma spectrometer4 ,,collector ,,cup ,,programmer ,,electrometer ,,deflection ,,plates ,illustration3 ,magnetometer4 ,illustration3 ,high-energy particle detector4 ,,collector ,,shield ,,can ,,quartz ,,fiber ,illustration3 ,microwave and infrared radiometers4 ,,reference ,,horns ,,microwave ,,radiometer ,,infrared ,,radiometer ,table #b4 ,mariner ,experiments ,experiment ,description ,experimenters ,microwave radiometer ,determine the ,dr4 ,a4 ,h4 ,barrett1 temperature of the ,massachusetts planet surface and ,institute of details concerning ,technology2 ,d4 ,e4 its atmosphere ,jones1 ,,jpl2 ,dr4 ,j4 ,copeland1 ,army ,ordnance ,missile ,command and ,ewen-,knight ,corp42 ,dr4 ,a4 ,e4 ,lilley1 ,harvard ,college ,observatory ,infrared radiometer ,determine the ,dr4 ,l4 ,d4 ,kaplan1 ,,jpl structure of the and ,university of cloud layer and ,nevada2 ,dr4 ,g4 temperature ,neugebauer1 ,,jpl2 ,dr4 distributions at ,c4 ,sagan1 ,university cloud altitudes of ,california1 ,berkeley1 and ,harvard ,college ,observatory ,magnetometer ,measure planetary and ,p4 ,j4 ,coleman1 ,,nasa2 interplanetary ,dr4 ,l4 ,davis1 magnetic fields ,caltech2 ,dr4 ,e4 ,j4 ,smith1 ,,jpl2 ,dr4 ,c4 ,p4 ,sonett1 ,,nasa ,ion chamber and ,measure high-energy ,dr4 ,h4 ,r4 ,anderson1 matched cosmic radiation ,,jpl2 ,dr4 ,h4 ,v4 ,neher1 ,geiger-,mueller tubes ,caltech ,anton special-purpose ,measure lower ,dr4 ,j4 ,van ,allen and tube radiation 7especially ,l4 ,frank1 ,state near ,venus7 ,university of ,iowa ,cosmic dust detector ,measure the flux of ,w4 ,m4 ,alexander1 cosmic dust ,goddard ,space ,flight ,center1 ,,nasa ,solar plasma ,measure the intensity ,m4 ,neugebauer and ,dr4 spectrometer of low-energy ,c4 ,w4 ,snyder1 ,,jpl positively charged particles from the ,sun ,four experiments for investigation of interplanetary space and the regions near ,venus employed3 a magnetometer2 high-energy charged particle detectors1 including an ionization chamber and ,geiger-,mueller radiation counters2 a cosmic dust detector2 and a solar plasma detector4 ,these six scientific experiments represented the cooperative efforts of scientists at nine institutions3 ,the ,army ,ordnance ,missile ,command1 the ,ewen-,knight ,corp41 the ,california ,institute of ,technology1 the ,goddard ,space ,flight ,center of ,,nasa1 ,harvard ,college ,observatory1 the ,jet ,propulsion ,laboratory1 the ,massachusetts ,institute of ,technology1 the ,state ,universities of ,iowa and ,nevada1 and the ,university of ,california at ,berkeley4 ,table #b lists the experiments1 the experimenters1 and their affiliations4 ,at the ,jet ,propulsion ,laboratory1 the integration of the scientific experiments and the generation of a number of them were carried out under the direction of ,dr4 ,manfred ,eimer4 ,r4 ,c4 ,wyckoff was the project scientist and ,j4 ,s4 ,martin was responsible for the engineering of the scientific experiments4 ,,data ,,conditioning ,,system ,mariner's scientific experiments were controlled and their outputs processed by a data conditioning system which gathered the information from the instruments and prepared it for transmission to the ,earth by telemetry4 ,in this function1 the data system acted as a buffer between the science systems and the spacecraft data encoder4 ,the pulse output of certain of the science instruments was counted and the voltage amplitude representations of other instruments were converted from analog form to a binary digital equivalent of the information signals4 ,the data conditioning system also included circuits to permit time-sharing of the telemetry channels with the spacecraft engineering data1 generation of periodic calibration signals for the radiometer and magnetometer1 and control of the direction and speed of the radiometer scanning cycle4 ,during ,mariner's cruise mode1 the data conditioning system was used for processing both engineering and science data4 ,if the spacecraft lost lock on the ,sun or the ,earth during the cruise mode1 no scientific data would be telemetered during the reorientation period4 ,engineering data were sampled and transmitted for about #ag seconds during every #cg-second interval4 ,the planetary encounter mode involved only science and no engineering data transmission4 ,in this mode1 the science data were sampled during #bj-second intervals4 ,,cosmic ,,dust ,,detector ,the cosmic dust detector on ,mariner ,,ii was designed to measure the flux density1 direction1 and momentum of interplanetary dust particles between the ,earth and ,venus4 ,these measurements were concerned with the particles' direction and distance from the ,sun1 the momentum with respect to the spacecraft1 the nature of any concentrations of the dust in streams1 variations in cosmic dust flux with distance from the ,earth and ,venus1 and the possible effects on manned flight4 ,mariner's cosmic dust instrument could detect a particle as small as something like a billionth of a gram1 or about five-trillionths of a pound4 ,this type of sensor had been used on rockets even before ,explorer ,i4 ,it had yielded good results on ,pioneer ,i in the region between the ,earth and the ,moon4 ,the instrument was a #ee-square-inch acoustical detector plate1 or sounding board1 made of magnesium4 ,a crystal microphone was attached to the center of the plate4 ,the instrument could detect both low- and high-momentum particles and also provide a rough idea of their direction of travel4 ,the dust particle counters were read once each #cg seconds during the cruise mode4 ,this rate was increased to once each #bj seconds during the encounter with ,venus4 ,the instrument was attached to the top of the basic hexagonal structure2 it weighed #a4he pounds1 and consumed only #j4h watt of power4 ,,solar ,,plasma ,,experiment ,in order to investigate the phenomena associated with the movement of plasma 7charged particles of low energy and density streaming out from the ,sun to form the so-called 8solar wind07 in interplanetary space1 ,mariner carried a solar plasma spectrometer that measured the flux and energy spectrum of positively charged plasma components with energies in the range #bdj to #hdjj volts4 ,the extremely sensitive plasma detector unit was open to space1 consumed #a watt of power1 and consisted of four basic elements3 curved electrostatic deflection plates and collector cup1 electrometer1 a sweep amplifier1 and a programmer4 ,the curved deflector plates formed a tunnel that projected from the chassis on the spacecraft hexagon in which the instrument was housed4 ,pointed toward the ,sun1 the gold-plated magnesium deflector plates gathered particles from space4 ,since the walls of the tunnel each carried different electrical charges1 only particles with just the correct energy and speed could pass through and be detected by the collector cup without striking the charged walls4 ,a sensitive electrometer circuit then measured the current generated by the flow of the charged particles reaching the cup4 ,the deflection plates were supplied by amplifier-generated voltages which were varied in #aj steps1 each lasting about #ah seconds1 allowing the instrument to measure protons with energies in the #bdj to #h1djj electron volt range4 ,the programmer switched in the proper voltage and resistances4 ,,high-,,energy ,,radiation ,,experiment ,mariner carried an experiment to measure high-energy radiation in space and near ,venus4 ,the charged particles measured by ,mariner were primarily cosmic rays 7protons or the nuclei of hydrogen atoms71 alpha particles 7nuclei of helium atoms71 the nuclei of other heavier atoms1 and electrons4 ,the study of these particles in space and those which might be trapped near ,venus was undertaken in the hope of a better understanding of the dynamics of the solar system and the potential hazards to manned flight4 ,the high-energy radiation experiment consisted of an ionization chamber and detectors measuring particle flux 7velocity times density71 all mounted in a box measuring #f #f #b inches and weighing just under #c pounds4 ,the box was attached halfway up the spacecraft superstructure in order to isolate the instruments as much as possible from secondary emission particles produced when the spacecraft was struck by cosmic rays1 and to prevent the spacecraft from blocking high-energy radiation from space4 ,the ionization chamber had a stainless steel shell #e inches in diameter1 with walls only #a_/ajj-;inch thick4 ,the chamber was filled with argon gas into which was projected a quartz fibre next to a quartz rod4 ,a charged particle entering the chamber would leave a wake of ions in the argon gas4 ,negative ions accumulated on the rod1 reducing the potential between the rod and the spherical shell1 eventually causing the quartz fibre to touch the rod4 ,this action discharged the rod1 producing an electrical pulse which was amplified and transmitted to the ,earth4 ,the rod was then recharged and the fibre returned to its original position4 ,in order to penetrate the walls of the chamber1 protons required an energy of #aj million electron volts 7,mev71 electrons needed #j4e ,mev1 and alpha particles #dj ,mev4 ,the particle flux detector incorporated three ,geiger-,mueller tubes1 two of which formed a companion experiment to the ionization chamber2 each generated a current pulse whenever a charged particle was detected4 ,one tube was shielded by an #h_/a1jjj-;inch-thick stainless steel sleeve1 the other by a #bd_/a1jjj-;inch-thick electron-stopping beryllium shield4 ,thus1 the proportion of particles could be determined4 ,the third ,geiger-,mueller tube was an end-window ,anton-type sensor with a mica window that admitted protons with energies greater than #j4e ,mev and electrons1 #dj1jjj electron volts4 ,a magnesium shield around the rest of the tube enabled the instrument to determine the direction of particles penetrating only the window4 ,the three ,geiger-,mueller tubes protruded from the box on the superstructure of the spacecraft4 ,the end-window tube was inclined #bj degrees from the others and #gj degrees from the spacecraft-,sun line since it had to be shielded from direct solar exposure4 ,,the ,,magnetometer ,mariner carried a magnetometer to measure the magnetic field in interplanetary space and in the vicinity of ,venus4 ,lower sensitivity limit of the instrument was about #e gamma4 ,a gamma is a unit of magnetic measurement and is equal to #aj or #a_/ajj1jjj oersted1 or #a_/cj1jjj of the ,earth's magnetic field at the equator4 ,the nails in one of your shoes would probably produce a field of about #a gamma at a distance of approximately #d feet4 ,housed in a #f- #c-;inch metal cylinder1 the instrument consisted of three magnetic core sensors1 each aligned on a different axis to read the three magnetic field components and having primary and secondary windings4 ,the presence of a magnetic field altered the current in the secondary winding in proportion to the strength of the field encountered4 ,the magnetometer was attached near the top of the superstructure1 just below the omni-antenna1 in order to remove it as far as possible from any spacecraft components having magnetic fields of their own4 ,an auxiliary coil was wound around each of the instrument's magnetic sensor cores to compensate for permanent magnetic fields existing in the spacecraft itself4 ,these spacecraft fields were measured at the magnetometer before launch and1 in flight1 the auxiliary coils carried currents of sufficient strength to cancel out the spacecraft's magnetic fields4 ,the magnetometer reported almost continuously on its journey and for #bj days after encounter4 ,during the encounter1 observations were made each #bj seconds on each of the three components of the magnetic field4 ,,microwave ,,radiometer ,a microwave radiometer on board ,mariner ,,ii was designed to scan ,venus during encounter at two wavelengths3 #ac4e and #ai millimeters4 ,the radiometer was intended to help settle some of the controversies about the origin of the apparently high surface temperature emanating from ,venus1 and the value of the surface temperature4 ,the equipment included a #ai-;inch-diameter parabolic antenna mounted above the basic hexagonal structure on a swivel driven in a #abj-;degree scanning motion by a motor4 ,the radiometer electronics circuits were housed behind the antenna dish4 ,the antenna was equipped with a diplexer1 which allowed it to receive both wavelengths at once without interference1 and to compare the signals emanating from the two reference horns with those from the planet4 ,the reference horns were pointed away from the main antenna beam so they would look into deep space as ,mariner passed ,venus4 ,this feature allowed the antenna to 8bring in0 a reference temperature of approximately absolute zero during encounter4 ,the microwave radiometer was to be turned on #aj hours before the encounter began4 ,an electric motor was then to start a scanning or 8nodding0 motion of #abj degrees at the rate of #a degree per second4 ,upon radiometer contact with the planet1 this scanning rate would be reduced to #a_/aj degree per second as long as the planetary disk was scanned4 ,a special command system in the data conditioning system would reverse or normalize the direction of scan as the radiometer reached the edge or limb of the planet4 ,the signals from the antenna and the reference horns were to be processed and the data handled in a receiver1 located behind the antenna1 which measured the difference between the signals from ,venus and the reference signals from space4 ,the information was then to be telemetered to the ,earth4 ,the microwave radiometer was automatically calibrated twenty-three times during the mission by a sequence originating in the data conditioning system1 so that the correct functioning of the instrument could be determined before the encounter with ,venus4 ,,infrared ,,radiometer ,the infrared radiometer was a companion experiment to the microwave instrument and was rigidly mounted to the microwave antenna so that both radiometers would look at the same area of ,venus with the same scanning rate4 ,the instrument detected radiation in the #h to #i and #aj to #aj4h micron regions of the infrared spectrum4 ,the infrared radiometer had two optical sensors4 ,as the energy entered the system1 it was 8chopped0 by a rotating disk1 alternately passing or comparing emissions from ,venus and from empty space4 ,the beam was then split by a filter into the two wavelength regions4 ,the output was then detected1 processed1 and transmitted to the ,earth4 ,the infrared radiometer measured #f inches by #b inches1 weighed #b4g pounds1 and consumed #b watts of power4 ,the instrument was equipped with a calibration plate which was mounted on a superstructure truss adjacent to the radiometer4 ,,mariner',s ,,scientific ,,objectives ,equipped with these instruments and with the mechanism for getting the measurements back to ,earth1 ,mariner ,,ii was prepared to look for the answers to some of the questions inherent in its over-all mission objectives3 #a4 ,the investigation of interplanetary space between the ,earth and ,venus1 measuring such phenomena as the cosmic dust1 the mysterious plasma or solar winds1 high-energy cosmic rays from space outside our solar system1 charged particles from the ,sun1 and the magnetic fields of space4 #b4 ,the experiments to be performed near ,venus 7at about #ba1aej miles out from the surface7 in an effort to understand its magnetic fields1 radiation belts1 the temperature and composition of its clouds1 and the temperature and conditions on the surface of the planet4 ,,chapter #i ,,the ,,legacy ,,of ,,mariner ,if intelligent life had existed on ,venus on the afternoon of the ,earth's ,december #ad1 #aifb1 and if it could have seen through the clouds1 it might have observed ,mariner ,,ii approach from the night side1 drift down closer1 cross over to the daylight face1 and move away toward the ,sun to the right4 ,the time was the equivalent of #ab3cd p4m4 along the ,pacific ,coast of the ,united ,states1 where the spacecraft was being tracked4 ,mariner ,,ii had reached the climax of its #ahj-million-mile1 #aji-;day trip through space4 ,the #ce-minute encounter with ,venus would tell ,earth scientists more about our sister planet than they had been able to learn during all the preceding centuries4 ,,space ,,without ,,dust8 ,before ,mariner1 scientists theorized about the existence of clouds of cosmic dust around the ,sun4 ,a knowledge of the composition1 origin1 and the dynamics of these minute particles is necessary for study of the origins and evolution of the solar system4 ,tiny particles of cosmic dust 7some with masses as low as #a4c #aj gram or about one-trillionth of a pound7 were thought to be present in the solar system and have been recorded by satellites in the near-,earth regions4 ,these microcosmic particles could be either the residue left over after our solar system was formed some #e billion years ago1 possibly by condensation of huge masses of gas and dust clouds2 or1 the debris deposited within our system by the far-flung and decaying tails of passing comets2 or1 the dust trapped from galactic space by the magnetic fields of the ,sun and the planets4 ,analysis of the more than #a1gjj hours of cosmic dust detector data recovered from the flight of ,mariner ,,ii seems to indicate that in the region between the ,earth and ,venus the concentration of tiny cosmic dust particles is some ten-thousand times less than that observed near the ,earth4 ,during the #abi days 7including the post-encounter period7 of ,mariner's mission1 the data showed only one dust particle impact which occurred in deep space and not near ,venus4 ,equivalent experiments near ,earth 7on board ,earth satellites7 have yielded over #c1gjj such impacts within periods of approximately #ejj hours4 ,the cause of this heavy near-,earth concentration1 the exact types of particles1 and their source are still unknown4 ,the cosmic dust experiment performed well during the ,mariner mission4 ,although some calibration difficulty was observed about two weeks before the ,venus encounter1 possibly caused by overheating of the sensor crystal1 there was no apparent effect in the electronic circuits4 ,,the ,,ubiquitous ,,solar ,,wind ,for some time prior to ,mariner1 scientists postulated the existence of a so-called plasma flow or 8solar wind0 streaming out from the ,sun1 to explain the motion of comet tails 7which always point away from the ,sun1 perhaps repelled by the plasma71 geomagnetic storms1 aurorae1 and other such disturbances4 7,plasma is defined as a gas in which the atoms are dissociated into atomic nuclei and electrons1 but which1 as a whole1 is electrically neutral47 ,the solar wind was thought to drastically alter the configuration of the ,sun's external magnetic field4 ,plasma moving at extreme velocities is able to carry with it the lines of magnetic force originating in the ,sun's corona and to distort any fields it encounters as it moves out from the ,sun4 ,it was believed that these moving plasma currents are also capable of altering the size of a planet's field of magnetic flux4 ,when this happens1 the field on the sunlit face of the planet is compressed and the dark side has an elongated expansion of the field4 ,for example1 the outer boundary of the ,earth's magnetic field is pushed in by the solar wind to about #dj1jjj miles from the ,earth on the sunward side4 ,on the dark side1 the field extends out much farther4 ,the solar wind was also known to have an apparent effect on the movement of cosmic rays4 ,as the ,sun spots increase in the regular #aa-year cycle1 the number of cosmic rays reaching the ,earth from outside our solar system will decrease4 ,mariner ,,ii found that streams of plasma are constantly flowing out from the ,sun4 ,this fluctuating1 extremely tenuous solar wind seems to dominate interplanetary space in our region of the solar system4 ,the wind moves at velocities varying from about #bjj to #ejj miles per second 7about #gbj1jjj to #a1hjj1jjj miles per hour71 and measures up to perhaps a million degrees ,fahrenheit 7within the subatomic structure74 ,with the solar plasma spectrometer working at ten different energy levels1 ,mariner required #c4g minutes to run through a complete energy spectrum4 ,during the #abc days1 when readings were made1 a total of #dj1jjj such spectra were recorded4 ,plasma was monitored on #ajd of those #abc days1 and on every one of the spectra1 the plasma was always present4 ,mariner showed that the energies of the particles in the solar winds are very low1 on the order of a few hundred or few thousand electron volts1 as compared with the billions and trillions of electron volts measured in cosmic radiation4 ,the extreme tenuousity or low density of the solar wind is difficult to comprehend3 about #aj to #bj protons 7hydrogen nuclei7 and electrons per cubic inch4 ,but despite the low energy and density1 solar wind particles in our region of the solar system are billions of times more numerous than cosmic rays and1 therefore1 the total energy content of the winds is much greater than that of the cosmic rays4 ,mariner found that when the surface of the ,sun was relatively inactive1 the velocity of the wind was a little less than #bej miles per second and the temperature a few hundred thousand degrees4 ,the plasma was always present1 but the density and the velocity varied4 ,flare activity on the ,sun seemed to eject clouds of plasma1 greatly increasing the velocity and density of the winds4 ,where the particles were protons1 their energies ranged from #gej to #b1ejj electron volts4 ,the experiment also showed that the velocity of the plasma apparently undergoes frequent fluctuations of this type4 ,on approximately twenty occasions1 the velocity increased within a day or two by #bj to #ajj4 ,these disturbances seemed to correlate well with magnetic storms observed on the ,earth4 ,in several cases1 the sudden increase in the solar plasma flux preceded various geomagnetic effects observed on the ,earth by only a short time4 ,the ,mariner solar plasma experiment was the first extensive measurement of the intensity and velocity spectrum of solar plasma taken far enough from the ,earth's field so that the ,earth would have no effect on the results4 ,,high-,,energy ,,particles3 ,,fatal ,,dosage8 ,speculation has long existed as to the amount of high-energy radiation 7from cosmic rays and particles from the ,sun with energies in the millions of electron volts7 present within our solar system and as to whether exposure would be fatal to a human space traveler4 ,this high-energy type of ionizing radiation is thought to consist of the nuclei of such atoms as hydrogen and helium1 and of electrons1 all moving very rapidly4 ,the individual particles are energetic enough to penetrate considerable amounts of matter4 ,the concentration of these particles is apparently much lower than that of low-energy plasma4 ,the experiments were designed to detect three types of high-energy radiation particles3 the cosmic rays coming from outside the solar system1 solar flare particles1 and radiation trapped around ,venus 7as that which is found in the ,earth's ,van ,allen ,belt74 ,these high-energy radiation particles 7also thought to affect aurorae and radio blackouts on the ,earth7 measure from about one hundred thousand electron volts up to billions of volts4 ,the distribution of this energy is thought to be uniform outside the solar system and is assumed to move in all directions in a pattern remaining essentially constant over thousands of years4 ,inside the solar system1 the amount of such radiation reaching the ,earth is apparently controlled by the magnetic fields found in interplanetary space and near the ,earth4 ,the number of cosmic rays changes by a large amount over the course of an #aa-year ,sun-spot cycle1 and below a certain energy level 7#e1jjj ,mev7 few cosmic rays are present in the solar system4 ,they are probably deflected by plasma currents or magnetic fields4 ,mariner's charged particles experiment indicated that cosmic radiation 7bombardment by cosmic rays71 both from galactic space and those particles originating in the ,sun1 would not have been fatal to an astronaut1 at least during the four-month period of ,mariner's mission4 ,the accumulated radiation inside the counters was only #c roentgens1 and during the one solar storm recorded on ,october #bc and #bd1 the dosage measured only about roentgen4 ,in other words1 the dosage amounts to about one-thousandth of the usually accepted 8half-lethal0 dosage1 or that level at which half of the persons exposed would die4 ,an astronaut might accept many times the dosage detected by ,mariner ,,ii without serious effects4 ,the experiment also showed little variation in density of charged particles during the trip1 even with a #cj decrease in distance from the ,sun1 and no apparent increase due to magnetically trapped particles or radiation belts near ,venus as compared with interplanetary space4 ,however1 these measurements were made during a period when the ,sun was slowly decreasing in activity at the end of an #aa-year cycle4 ,the ,sun spots will be at a minimum in #aifd-aife1 when galactic cosmic rays will sharply increase4 ,further experiments are needed to sample the charged particles in space under all conditions4 ,the lack of change measured by the ionization chamber during the mission was significant2 the cosmic-ray flux of approximately #c particles per square centimeter per second throughout the flight was an unusually constant value4 ,a clear increase in high-energy particles 7#aj ,mev to about #hjj ,mev7 emitted by the ,sun was noted only once3 a flare-up between #g3db and #h3de a4m41 ,,pst1 ,october #bc4 ,the ionization chamber reading began to increase before the flare disappeared4 ,from a background reading of #fgj ion pairs per cubic centimeter per second per standard atmosphere1 it went to a peak value of #ah1jjj1 varied a bit1 and remained above #aj1jjj for #f hours before gradually decreasing over a period of several days4 ,meanwhile1 the flux of the particles detected by the ,geiger counter rose from the background count of #c to a peak of #af per square centimeter per second4 ,ionization thus increased much more than the number of particles1 indicating to the scientists that the high-energy particles coming from the ,sun might have had much lower average energies than the galactic cosmic rays4 ,illustration3 ,data obtained by microwave radiometer are illustrated at left2 results of infrared radiometer experiment are shown at right4 ,note how moving spacecraft sees more of atmosphere along limb or edge of planet1 less in center4 ,in contrast1 the low-energy experiment detected the ,october #bc event1 and eight or ten others not seen by the high-energy detectors4 ,these must have been low-penetrating particles excluded by the thicker walls of the high-energy instrument4 ,these particles were perhaps protons between #j4e and #aj ,mev or electrons between #j4jd and #j4e ,mev4 ,at #bj1jjj miles from the ,earth1 the rate at which high-energy particles have been observed has been recorded at several thousand per second4 ,with ,mariner at approximately the same distance from ,venus1 the average was only one particle per second1 as it had been during most of the month of ,november in space4 ,such a rate would indicate a low planetary magnetic field1 or one that did not extend out as far as ,mariner's #ba1eih-mile closest approach to the surface4 ,mariner ,,ii measured and transmitted data in unprecedented quantity and quality during the long trip4 ,in summary1 ,mariner showed that1 during the measuring period1 particles were numerous in the energy ranges from a few hundred to #a1jjj electron volts4 ,protons in the range #j4e to #aj ,mev were not numerous1 but at times the flux 7density7 was several times that of cosmic rays4 ,almost no protons were shown in the #aj to #hjj ,mev range1 except during solar flares when the particles in this range were numerous4 ,above #hjj ,mev 7primarily those cosmic rays entering interplanetary space from outside the solar system7 the number decreased rapidly as the energy increased1 the average total being about #c per centimeter per second4 ,during one #cj-;day period in ,november and ,december1 the low-energy counter saw only two small increases in radiation intensity4 ,at this time1 the mean velocity of the solar wind was considerably lower than during ,september and ,october4 ,this might suggest that high-velocity plasma and low-energy cosmic rays might both originate from the same solar source4 ,a ,,magnetic ,,field8 ,prior to the ,mariner ,,ii mission1 no conclusive evidence had ever been presented concerning a ,venusian magnetic field and nothing was known about possible fluid motions in a molten core or other hypotheses concerning the interior of the planet4 ,scientists assumed that ,venus had a field somewhat similar to the ,earth's1 although possibly reduced in magnitude because of the apparently slow rate of rotation and the pressure of solar plasma4 ,many questions had also been raised concerning the nature of the atmosphere1 charged particles in the vicinity of the planet1 magnetic storms1 and aurorae4 ,good magnetometer data from ,mariner ,,ii would help solve some of these problems4 ,mariner's magnetometer experiment also sought verification of the existence and nature of a steady magnetic field in interplanetary space4 ,this would be important in understanding the charged particle balance of the inner solar system4 ,other objectives of the experiment were to establish both the direction and the magnitude of long-period fluctuations in the interplanetary magnetic field and to study solar disturbances and such problems in magnetohydrodynamics 7the study of the motion of charged particles and their surrounding magnetic fields7 as the existence and effect of magnetized and charged plasmas in space4 ,the strength of a planet's field is thought to be closely related to its rate of rotation--the slower the rotation1 the weaker the field4 ,as a consequence1 if ,venus' field is simple in structure like the ,earth's1 the surface field should be #e to #aj that of the ,earth4 ,if the structure of the field is complex1 the surface field in places might exceed the ,earth's without increasing the field along ,mariner's trajectory to observable values4 ,most of the phenomena associated with the ,earth's magnetic field are likely to be significantly modified or completely absent in and around ,venus4 ,auroral displays and the trapping of charged particles in radiation belts such as our ,van ,allen would be missing4 ,the field of the ,earth keeps low- and moderate-energy cosmic rays away from the top of the atmosphere1 except in the polar regions4 ,the cosmic ray flux at the top of ,venus' atmosphere is likely to correspond everywhere to the high level found at the ,earth's poles4 ,illustration3 ,as it encountered ,venus1 ,mariner ,,ii made three scans of the planet4 ,,sun ,,direction ,,of ,,scan ,,data ,,readings 7#ah ,,total7 ,in contrast to ,venus1 ,jupiter1 which is ten times larger in mass and volume and rotates twice as fast as the ,earth1 has a field considerably stronger than the ,earth's4 ,the ,moon has a field on the sunlit side 7according to ,russian measurements7 which1 because of the ,moon's slow rotation rate1 is less than of #a of the ,earth's at the ,equator4 ,thus1 a planet's rotation1 if at a less rapid rate than the ,earth's1 seems to produce smaller magnetic fields4 ,this theory is consistent with the idea of a planetary magnetic field resulting from the dynamo action inside the molten core of a rotating planet4 ,the ,sun1 on the whole1 has a fairly regular dipole field4 ,superimposed on this are some very large fields associated with disturbed regions such as spots or flares1 which produce fields of very great intensities4 ,these solar fields are drawn out into space by plasma flow4 ,although relatively small in magnitude1 these fields are an important influence on the propagation of particles4 ,and the areas in question are very large--something on the order of an astronomical unit4 ,mariner ,,ii seemed to show that1 in space1 a generally quiet magnetic-field condition was found to exist1 measuring something less than #aj gamma and fluctuating over periods of #a second to #a minute4 ,as ,mariner made its closest approach to ,venus1 the magnetometer saw no significant change1 a condition also noted by the radiation and solar plasma detectors4 ,the magnetic field data looked essentially as they had in interplanetary space1 without either fluctuations or smooth changes4 ,the encounter produced no slow changes1 nor was there a continuous fluctuation as in the interplanetary regions4 ,there was no indication of trapped particles or near-,venus modification in the flow of solar plasma4 ,on the ,earth's sunny side1 a definite magnetic field exists out to #dj1jjj miles1 and on the side away from the ,sun considerably farther4 ,if ,venus' field had been similar to the ,earth's1 a reading of #ajj to #bjj gamma1 a large cosmic-ray count1 and an absence of solar plasma should have been shown1 but none of these phenomena were noted by ,mariner4 ,these results do not prove that ,venus definitely has no magnetic field1 but only that it was not measurable at ,mariner's #ba1eih-mile point of closest approach4 ,the slow rotation rate and the pressure of the solar winds probably combine to limit the field to a value one tenth of the ,earth's4 ,since ,mariner passed ,venus on the sunlit side1 readings are required on the dark side in order to confirm the condition of the magnetic field on that side of the planet1 which normally should be considerably extended4 ,,the ,,surface3 ,,how ,,hot8 ,before ,mariner1 scientists had offered two main theories about the surface of ,venus3 ,it had either an electrically charged ionosphere causing false high-temperature readings on ,earth instruments despite a cool surface1 or a hot surface with clouds becoming increasingly colder with altitude4 ,the cool-surface theory supposed an ionosphere with a layer of electrons having a density thousands of times that of the ,earth's upper atmosphere4 ,microwave radiations from this electrical layer would cause misleading readings on ,earth instruments4 ,as a space probe scanned across such an atmosphere1 it would see the least amount of charged ionosphere when looking straight down1 and the most concentrated amount while scanning the limb or edge4 ,in the latter case1 it would be at an angle and would show essentially a thickening effect of the atmosphere because of the curvature of the planet4 ,as the probe approached the edge1 the phenomenon known as 8limb brightening0 would occur1 since the instruments would see more of the electron-charged ionosphere and little if any of the cooler surface4 ,the temperature readings would1 therefore1 be correspondingly higher at the limbs4 ,the other theory1 held by most scientists1 visualized a hot surface on ,venus1 with no heavy concentration of electrons in the atmosphere1 but with cooler clouds at higher altitudes4 ,thus1 the spacecraft would look at a very hot planet from space1 covered by colder1 thick clouds4 ,straight down1 the microwave radiometer would see the hot surface through the clouds4 ,when approaching the limb1 the radiations would encounter a thicker concentration of atmosphere and might not see any of the hot surface4 ,this condition1 8limb darkening10 would be characterized by temperatures decreasing as the edges of the planet were approached4 ,an instrument capability or resolution much higher than that available from the ,earth was required to resolve the limb-brightening or limb-darkening controversy4 ,mariner's radiometer would be able to provide something like one hundred times better resolution than the ,earth-based measurements4 ,at #aa3ei a4m41 ,,pst1 on ,december #ad1 #aifb1 ,mariner's radiometers began to scan the planet ,venus in a nodding motion at a rate of #j4a degree per second and reaching an angular sweep of nominally #abj degrees4 ,the radiometers had been switched on #f hours before the encounter with ,venus and they continued to operate for another hour afterward4 ,the microwave radiometer looked at ,venus at a wavelength of #ac4e millimeters and #ai millimeters4 ,the #ac4e-millimeter region was the location of a microwave water absorption band within the electromagnetic spectrum1 but it was not anticipated that it would detect any water vapor on ,venus4 ,these measurements would allow determination of atmospheric radiation1 averaging the hot temperatures near the surface1 the warmer clouds at lower levels1 and the lower temperatures found in the high atmosphere4 ,if the atmosphere were a strong absorber of microwave energy at #ac4e millimeters1 only the temperature of the upper layers would be reported4 ,unaffected by water vapor1 #ai-millimeter radiations could be detected from deeper down into the cloud cover1 perhaps from near or at the planet's surface4 ,large temperature differences between the #ai- and #ac4e millimeter readings would indicate the relative amount of water vapor present in the atmosphere4 ,the #ai-millimeter radiations would also test the limb-brightening theory4 ,during its scanning operation1 ,mariner telemetered back to ,earth about #ah digital data points1 represented as voltage fluctuations in relation to time4 ,the first scan was on the dark side1 going up on the planet3 the distance from the surface was #af1dgi miles at midscan1 and the brightness temperature was #cfi degrees ,f4 ,the second scan nearly paralleled the terminator 7junction of light and dark sides7 but crossed it going down2 it was made from #ad1ieg miles at midscan and showed a temperature of #eff degrees ,f4 ,the final scan1 #ac1ggf miles at midpoint1 showed #bfa degrees ,f as it swept across the sunlit side of ,venus in an upward direction4 ,the brightness temperature recorded by ,mariner's radiometer is not the true temperature of the surface4 ,it is derived from the amount of light or radio energy reflected or emitted by an object4 ,if the object is not a perfect light emitter1 as most are not1 then the light and radio energy will be some fraction of that returned from a #ajj efficient body1 and the object is really hotter than the brightness measurement shows4 ,thus1 the brightness temperature is a minimum reading and in this case1 was lower than the actual surface temperature4 ,mariner's microwave radiometer showed no significant difference between the light and dark sides of ,venus and1 importantly1 higher temperatures along the terminator or night-and-day line of the planet4 ,these results would indicate no ionosphere supercharged with electrons1 but a definite limb-darkening effect1 since the edges were cooler than the center of the planet4 ,therefore1 considering the absorption characteristics of the atmosphere and the emissivity factor derived from earlier ,,jpl radar experiments1 a fairly uniform #hjj degrees ,f was estimated as a preliminary temperature figure for the entire surface4 ,venus is1 indeed1 a very hot planet4 ,,cloud ,,temperatures3 ,,the ,,infrared ,,readings ,mariner ,,ii took a close look at ,venus' clouds with its infrared radiometer during its #ce-minute encounter with the planet4 ,this instrument was firmly attached to the microwave radiometer so the two devices would scan the same areas of ,venus at the same rate and the data would be closely correlated4 ,this arrangement was necessary to produce in effect a stereoscopic view of the planet from two different regions of the spectrum4 ,because astronomers have long conjectured about the irregular dark spots discernible on the surface of ,venus' atmosphere1 data to resolve these questions would be of great scientific interest4 ,if the spots were indeed breaks in the clouds1 they would stand out with much better definition in the infrared spectrum4 ,if the radiation came from the cloud tops1 there would be no breaks and the temperatures at both frequencies measured by the infrared radiometer would follow essentially the same pattern4 ,the ,venusian atmosphere is transparent to the #h-micron region of the spectrum except for clouds4 ,in the #aj-micron range1 the lower atmosphere would be hidden by carbon dioxide4 ,if cloud breaks existed1 the #h-micron emissions would come from a much lower point1 since the lower atmosphere is fairly transparent at this wavelength4 ,if increasing temperatures were shown in this region1 it might mean that some radiation was coming up from the surface4 ,as a result of the ,mariner ,,ii mission1 scientists have hypothecated that the cold cloud cover could be about #ae miles thick1 with the lower base beginning about #de miles above the surface1 and the top occurring at #fj miles4 ,in this case1 the bottom of the cloud layer could be approximately #bjj degrees ,f2 at the top1 the readings vary from about minus #cj degrees ,f in the center of the planet to temperatures of perhaps minus #fj degrees to minus #gj degrees ,f along the edges4 ,this temperature gradient would verify the limb-darkening effect seen by the microwave radiometer4 ,at the center of ,venus1 the radiometer saw a thicker1 brighter1 hotter part of the cloud layer2 at the limbs1 it could not see so deeply and the colder upper layers were visible4 ,furthermore1 the temperatures along the cloud tops were approximately equally distributed1 indicating that both #h- and #aj-micron 8channels0 penetrated to the same depth and that both were looking at thick1 dense clouds quite opaque to infrared radiation4 ,both channels detected a curious feature along the lower portion of the terminator1 or the center line between the night and day sides of the planet4 ,in that region1 a spot was shown that was apparently about #bj degrees ,f colder than the rest of the cloud layer4 ,such an anomaly could result from higher or more opaque clouds1 or from such an irregularity as a hidden surface feature4 ,a mountain could force the clouds upward1 thus cooling them further1 but it would have to be extremely high4 ,the data allow scientists to deduce that not enough carbon dioxide was present above the clouds for appreciable absorption in the #aj-micron region4 ,this effect would seem to indicate that the clouds are thick and that there is little radiation coming up from the surface4 ,and1 if present1 water vapor content might be #a_/a1jjj of that in the ,earth's atmosphere4 ,since the cloud base is apparently at a very high temperature1 neither carbon dioxide nor water is likely to be present in quantity4 ,rather1 the base of the clouds must contain some component that will condense in small quantities and not be spectroscopically detected4 ,as a result of the two radiometer experiments1 the region below the clouds and the surface itself take on better definition4 ,certainly1 heat-trapping of infrared radiation1 or a 8greenhouse0 effect1 must be expected to support the #hjj degree ,f surface temperature estimated from the microwave radiometer data4 ,thus1 a considerable amount of energy-blanketing carbon dioxide must be present below the cloud base4 ,it is thought that some of the near-infrared sunlight might filter through the clouds in small amounts1 so that the sky would not be entirely black1 at least to human eyes1 on the sunlit side of ,venus4 ,there also may be some very small content of oxygen below the clouds1 and perhaps considerable amounts of nitrogen4 ,the atmospheric pressure on the surface might be very high1 about #bj times the ,earth's atmosphere or more 7equivalent to about #fjj inches of mercury1 compared with our #cj inches74 ,the surface1 despite the high temperature1 is not likely to be molten because of the roughness index seen in the earlier radar experiments1 and other indicators4 ,however1 the possibility of small molten metal lakes cannot be totally ignored4 ,the dense1 high-pressure atmosphere and the heat-capturing greenhouse effect could combine over long periods of time to carry the extremely high temperature around to the dark side of ,venus1 despite the slow rate of rotation1 possibly accounting for the relatively uniform surface temperatures apparently found by ,mariner ,,ii4 ,,the ,,radar ,,profile3 ,,measurements ,,from ,,earth ,in #aifa1 the ,jet ,propulsion ,laboratory conducted a series of experiments from its ,goldstone1 ,california1 ,,dsif ,station1 successfully bouncing radar signals off the planet ,venus and receiving the return signal after it had travelled #gj million miles in #f minutes4 ,in order to complement the ,mariner mission to ,venus1 the radar experiments were repeated from ,october to ,december1 #aifb 7during the ,mariner mission71 using improved equipment and refined techniques4 ,as in #aifa1 the experiments were directed by ,w4 ,k4 ,victor and ,r4 ,stevens4 ,the #aifa experiments used two #he-;foot antennas1 one transmitting #ac kilowatts of power at #b1chh megacycles1 the other receiving the return signal after the round trip to and from ,venus4 ,the most important result was the refinement of the astronomical unit--the mean distance from the ,earth to the ,sun--to a value of #ib1ief1bjj #cjj miles4 ,around #aiaj1 the astronomical unit1 plotted by classical optical methods1 was uncertain to #bej1jjj miles4 ,before the introduction of radar astronomy techniques such as those used at ,goldstone1 scientists believed that the astronomical unit was known to within #fj1jjj miles1 but even this factor of uncertainty would be intolerable for planetary exploration4 ,in radar astronomy1 the transit time of a radio signal moving at the speed of light 7#ahf1jjj miles per second7 is measured as it travels to a planet and back4 ,in conjunction with the angular measurement techniques used by earlier investigators1 this method permits a more precise calculation of the astronomical unit4 ,optical and radar measurements of the astronomical unit differ by #ej1jjj miles4 ,further refinement of both techniques should lessen the discrepancy between the two values4 ,the #aifa tests also established that ,venus rotates at a very slow rate1 possibly keeping the same face toward the ,sun at all times4 ,the reflection coefficient of the planet was estimated at #ab1 a bright value similar to that of the ,earth and contrasted with the ,moon's #b4 ,the average dielectric constant 7conductivity factor7 of the surface material seemed to be close to that of sand or dust1 and the surface was reported to be rough at a wavelength of #f inches4 ,the surface roughness was confirmed in #aifb4 ,since it is known that a rough surface will scatter a signal1 the radar tests were observed for such indications4 ,venus had a scattering effect on the radar waves similar to the ,moon's1 probably establishing the roughness of the ,venusian surface as more or less similar to the lunar terrain4 ,some of the most interesting work was done in reference to the rotation rate of ,venus4 ,a radar signal will spread in frequency on return from a target planet that is rotating and rough enough to reflect from a considerable area of its surface4 ,the spread of #e to #aj cycles per second noted on the ,venus echo would suggest a very slow rotation rate1 perhaps keeping the same face toward the ,sun1 or possibly even in a retrograde direction1 opposite to the ,earth's4 ,in the ,goldstone #aifb experiments1 ,venus was in effect divided into observation zones and the doppler effect or change in the returned signal from these zones was studied4 ,the rate of rotation was derived from three months of sampling with this radar mapping technique4 ,also1 the clear1 sharp tone characteristic of the transmitted radar signal was altered on return from ,venus into a fuzzy1 indistinct sound4 ,this effect seemed to confirm the slow retrograde rotation 7as compared with the ,earth7 indicated by the radar mapping and frequency change method4 ,in addition to these methods of deducing the slow rotation rate1 two other phenomena seemed to verify it3 a slowly fluctuating signal strength1 and the apparent progression of a bright radar spot across from the center of ,venus toward the outside edge4 ,as a result1 ,,jpl scientists revised their #aifa estimate of an equal ,venusian day and year consisting of #bbe ,earth days4 ,the new value for ,venus' rotation rate around its axis is #bcj ,earth days plus or minus #dj to #ej days1 and in a retrograde direction 7opposite to synchronous or ,sun-facing71 assuming that ,venus rotates on an axis perpendicular to the plane of its orbit4 ,thus1 on ,venus the ,sun would appear to rise in the west and cross to the east about once each ,venusian year4 ,if the period were exactly #bbe days retrograde1 the stars would remain stationary in the sky and ,venus would always face a given star rather than the ,sun4 ,a space traveller hovering several million miles directly above the ,sun would thus see ,venus as almost stopped in its rotation and possibly turning very slowly clockwise4 ,all the other planets of our system including the ,earth1 rotate counterclockwise1 except ,uranus1 whose axis is almost parallel to the plane of its orbit1 making it seem to roll around the ,sun on its side4 ,the rotation direction of distant ,pluto is unknown4 ,the ,goldstone experiments also studied what is known as the ,faraday rotation of the plane of polarization of a radio wave4 ,the results indicated that the ionization and magnetic field around ,venus are very low4 ,these data tend to confirm those gathered by ,mariner's experiments close to the planet4 ,the mass of ,venus was another value that had never been precisely established4 ,the mass of planetary bodies is determined by their gravitational effect on other bodies1 such as satellites4 ,since ,venus has no known natural satellite or moon1 ,mariner1 approaching closely enough to 8feel0 its gravity1 would provide the first opportunity for close measurement4 ,the distortion caused by ,venus on ,mariner's trajectory as the spacecraft passed the planet enabled scientists to calculate the mass with an error probability of #j4jae4 ,the value arrived at is #j4hadhe of the mass of the ,earth1 which is known to be approximately #ac4agc septillion 7#ac1agc1jjj1jjj1jjj1jjj1jjj1jjj1jjj7 pounds4 ,thus1 the mass of ,venus is approximately #aj4gbi septillion 7#aj1gbi1djh1ejj1jjj1jjj1jjj1jjj1jjj7 pounds4 ,in addition to these measurements1 the extremely precise tracking system used on ,mariner proved the feasibility of long-range tracking in space1 particularly in radial velocity1 which was measured to within #a_/aj of an inch per second at a distance of about #ed million miles4 ,as the mission progressed1 the trajectory was corrected with respect to ,venus to within #aj miles at encounter4 ,an interesting result was the very precise location of the ,goldstone and overseas tracking stations of the ,,dsif4 ,before ,mariner ,,ii1 these locations were known to within #ajj yards4 ,after all the data have been analyzed1 these locations will be redefined or 8relocated0 to within an error of only #bj yards4 ,mariner not only made the first successful journey to ,venus--it also helped pinpoint spots in the ,californian and ,australian deserts and the ,south ,african veldt with an accuracy never before achieved4 ,,chapter #aj ,,the ,,new ,,look ,,of ,,venus ,the historic mission of ,mariner ,,ii to the near-vicinity of ,venus and beyond has enabled scientists to revise many of their concepts of interplanetary space and the planet ,venus4 ,the composite picture1 taken from the six experiments aboard the spacecraft and the data from the ,,dsif radar experiments of #aifa and #aifb revealed the following3 --,interplanetary space between the ,earth and ,venus1 at least as it was during the four months of ,mariner's mission1 had a cosmic dust density some ten-thousand times lower than the region immediately surrounding the ,earth4 --,during this period1 the extremely tenuous1 widely fluctuating solar winds streamed continually out from the ,sun1 at velocities ranging from #bjj to #ejj miles per second4 --,an astronaut travelling through these regions in the last quarter of #aifb would not have been seriously affected by the cosmic and high-energy radiation from space and the ,sun4 ,he could easily have survived many times the amount of radiation detected by ,mariner's instruments4 --#aaa --,the astronomical unit1 as determined by radar1 the yardstick of our solar system1 stands at #ib1ief1bjj1 plus or minus #cjj miles4 --,the mass of ,venus in relation to the ,earth's is #j4hadhe1 with an error probability of #j4jae4 --,the rotation rate of ,venus is quite slow and is now estimated as equal to #bcj ,earth days1 plus or minus #dj to #ej days4 ,the rotation might be retrograde1 clockwise with respect to a ,sun-facing reference1 with the ,sun rising in the west and setting in the east approximately one ,venusian year later4 ,the planet seems to remain nearly star-fixed rather than permanently oriented with one face to the ,sun4 --,venus has no magnetic field discernible at the #ba1eih-mile approach of ,mariner ,,ii and at that altitude there were no regions of trapped high-energy particles or radiation belts1 as there are near the ,earth4 --,the clouds of ,venus are about #ae miles thick1 extending from a base #de miles above the surface to a top altitude of about #fj miles4 --,at the resolution of the ,mariner ,,ii infrared radiometer1 there were no apparent breaks in the cloud cover4 ,cloud-top temperature readings are about minus #cj degrees ,f near the center 7along the terminator71 and ranging down to minus #fj degrees to minus #gj degrees ,f at the limbs1 showing an apparent limb-darkening effect1 which would indicate a hot surface and the absence of a supercharged ionosphere4 --,a spot #bj degrees ,f colder than the surrounding area exists along the terminator in the southern hemisphere3 a high mountain could exist in this region1 but such an hypothesis is purely conjectural4 ,a bright radar reflection is also found on the ,equator in the same general region4 ,causes of these phenomena are not established4 --,at their base1 the clouds are about #bjj degrees ,f and probably are comprised of condensed hydrocarbons held in oily suspension4 ,below the clouds1 the atmosphere must be heavily charged with carbon dioxide1 may contain slight traces of oxygen1 and probably has a strong concentration of nitrogen4 --#aab --,as determined by the microwave radiometer1 ,venus' surface temperature averages approximately #hjj degrees ,f on both light and dark sides of the planet4 ,some roughness is indicated and the surface reflectivity is equivalent to that of dust and sand4 ,no water could be present at the surface but there is some possibility of small lakes of molten metal of one type or another4 --,some reddish sunlight1 in the filterable infrared spectrum1 may find its way through the #ae-mile-thick cloud cover1 but the surface is probably very bleak4 --,the heavy1 dense atmosphere creates a surface pressure of some twenty times that found on the ,earth1 or equal to about #fjj inches of mercury4 ,the mission was completed and the spacecraft had gone into an endless orbit around the ,sun4 ,but before ,mariner ,,ii lost its sing-song voice1 it produced #ac million data words of computer space lyrics to accompany the music of the spheres4 ,,appendix ,,subcontractors ,thirty-four subcontractors to ,,jpl provided instruments and other hardware for ,mariners ,i and ,,ii4 ,the subcontractors were3 ,aeroflex ,corporation ,jet vane actuators ,long ,island ,city1 ,new ,york ,american ,electronics1 ,inc4 ,transformer-rectifiers for flight ,fullerton1 ,california telecommunications ,ampex ,corporation ,tape recorders for ground telemetry ,instrumentation ,division and data handling equipment ,redwood ,city1 ,california ,applied ,development ,corporation ,decommutators and teletype encoders ,monterey ,park1 ,california for ground telemetry equipment ,astrodata1 ,inc4 ,time code translators1 time code ,anaheim1 ,california generators1 and spacecraft signal simulators for ground telemetry equipment ,barnes ,engineering ,company ,infrared radiometers ,stamford1 ,connecticut ,planet simulator ,bell ,aerospace ,corporation ,accelerometers and associated ,bell ,aerosystems ,division electronic modules ,cleveland1 ,ohio ,computer ,control ,company1 ,inc4 ,data conditioning systems ,framingham1 ,massachusetts ,conax ,corporation ,midcourse propulsion explosive ,buffalo1 ,new ,york valves ,squibs ,consolidated ,electrodynamics ,corp4 ,oscillographs for data reduction ,pasadena1 ,california ,consolidated ,systems ,corporation ,scientific instruments ,monrovia1 ,california ,operational support equipment ,dynamics ,instrumentation ,company ,isolation amplifiers for telemetry ,monterey ,park1 ,california ,operational support equipment ,electric ,storage ,battery ,company ,spacecraft batteries ,missile ,battery ,division ,raleigh1 ,north ,carolina ,electro-,optical ,systems1 ,inc4 ,spacecraft power conversion ,pasadena1 ,california equipment ,fargo ,rubber ,corporation ,midcourse propulsion fuel tank ,los ,angeles1 ,california bladders ,glentronics1 ,inc4 ,power supplies for data ,glendora1 ,california conditioning system ,groen ,associates ,actuators for solar panels ,sun ,valley1 ,california ,houston ,fearless ,corporation ,pin pullers ,torrance1 ,california ,kearfott ,division ,gyroscopes ,general ,precision1 ,inc4 ,los ,angeles1 ,california ,marshall ,laboratories ,magnetometers and associated ,torrance1 ,california operational support equipment ,matrix ,research and ,development ,power supplies for particle flux ,corporation detectors ,nashua1 ,new ,hampshire ,menasco ,manufacturing ,company ,midcourse propulsion fuel tanks and ,burbank1 ,california nitrogen tanks ,midwestern ,instruments ,oscillographs for data reduction ,tulsa1 ,oklahoma ,mincom ,division ,tape recorders for ground telemetry ,minnesota ,mining ,manufacturing and data handling equipment ,los ,angeles1 ,california ,motorola1 ,inc4 ,spacecraft command subsystems1 ,military ,electronics ,division transponders1 and associated ,scottsdale1 ,arizona operational support equipment ,nortronics ,attitude control gyro electronic1 ,division of ,northrop ,corporation autopilot electronic1 and antenna ,palos ,verdes ,estates1 ,california servo electronic modules1 long-range ,earth sensors and ,sun sensors ,ransom ,research ,verification and ground command ,division of ,wyle ,laboratories modulation equipment ,san ,pedro1 ,california ,rantec ,corporation ,transponder circulators and monitors ,calabasas1 ,california ,ryan ,aeronautical ,company ,solar panel structures ,aerospace ,division ,san ,diego1 ,california ,spectrolab ,solar cells and their installation ,division of ,textron ,electronics1 and electrical connection on ,inc4 solar panels ,north ,hollywood1 ,california ,state ,university of ,iowa ,calibrated ,geiger counters ,iowa ,city1 ,iowa ,sterer ,engineering ,manufacturing ,valves and regulators for midcourse ,company propulsion and attitude control ,north ,hollywood1 ,california systems ,texas ,instruments1 ,inc4 ,spacecraft data encoders and ,apparatus ,division associated operational support ,dallas1 ,texas equipment1 ground telemetry demodulators ,trans-,sonic1 ,inc4 ,transducers ,burlington1 ,massachusetts ,in addition to these subcontractors1 over #a1jjj other industrial firms contributed to the ,mariner ,project4 ,,footnotes #a,throughout this book 8,mariner0 refers to the successful ,mariner ,,ii ,venus mission4 ,mariner ,i was launched earlier but was destroyed when the launch vehicle flew off course4 #b;,for scientific reasons1 distances from ,venus are calculated from the center of the planet4 ,hereafter in this chapter1 these distances will be reckoned from the surface4 ,,index ,a ,,abma1 #ag ,agena ,b1 #ba1 #bb1 #dj ,antennas1 #ff ,goldstone1 description1 #gj1 #ga1 #gc onboard1 description1 #cj1 #ca directional control1 #cj ,pioneer tracking site1 #gj1 #ga ,,arpa1 #ag ,astronomical unit1 #aaa refinement1 #ajg ,atlantic ,missile ,range1 #b1 #aj1 #dc1 #hc ,atlas-,agena ,b1 #fc1 #eb ,atlas ,d1 #ai1 #ba1 #cf-ci1 #hi ,attitude control ,atlas ,d1 #ch ,earth acquisition1 #eh loss of control and reorientation1 #ef1 #fj ,attitude control system1 #ca1 #cb ,b ,battery1 #be1 #bg ,bumper-,,wac1 #ah ,c ,c-#acc aircraft1 #dc ,centaur1 #h ,central ,computer and ,sequencer1 #bh commands1 #ef1 #eh failure at encounter1 #fb midcourse maneuver control1 #ei ,central ,computing ,facility1 #ha1 #hb ,charged particles1 #ac1 #ij ,charged particle detector1 #ce1 #hh ,computers1 data processing1 #hd ,corporal ,e1 #ah ,cosmic dust1 #ac density1 #aaj distribution and mass1 #id1 #ie measurement1 #hi ,cosmic dust detector1 #ce1 #fh1 #hg1 #hi ,cosmic radiation1 #ac1 #if ,cosmic ray flux1 #ih ,d ,data conditioning system1 #hh ,data processing1 #cj1 #gd1 #he ,,ccf1 equipment and operation1 #hb1 #hc launch and tracking operations1 #hc telemetry data1 #hd transmission time1 #hh ,detectors charged particle1 #ce cosmic dust1 #ce solar plasma1 #ce ,,dsif1 #gc1 #gd1 #ge1 #hb1 #hc1 #hd functions1 #fh ,goldstone1 #a1 #fd1 #fg-gi1 #fh1 #fi1 #gj1 #ga1 #gc1 #ge1 #hd1 #ajg1 #ajh1 #aji ,johannesburg1 #fd1 #fg1 #fh1 #gc ,mobile1 #fh1 #gc1 #hj tracking during midcourse maneuver1 #ef orientation1 #ef ,woomera1 #fg1 #fh1 #ga1 #gc1 #ge ,e ,earth sensor final orientation commands1 #fd ,september #h1 crises and recovery1 #fj ,echo ,project1 #fi ,echo site functions1 #ga ,electronics equipment weight1 #be ,explorer ,i1 #ai ,experiments1 #ce ,anton special purpose tube1 #hg atmospheric investigation1 #he charged particle detector1 #hh1 #if-ajj density variation data1 #ih radiation hazard findings1 #ih cosmic dust detector data1 #hg-hi1 #id1 #ie high energy radiation1 #ij infrared radiometer1 #hg1 #ic ion chamber and ,geiger-,mueller tubes1 #hg magnetometers1 #hg1 #hh microwave radiometer1 #hg1 #ia-ic objectives1 #ac1 #ic processing of data1 #he radiometers1 #he1 #aje1 #ajf responsible organizations1 #hh results1 #aaj-aab solar plasma detector1 #hg-ij temperature investigation1 #he transmission of data1 #hh weight1 #be ,g ,geiger counter1 #ih ,geiger-,mueller tubes1 #hg1 #ia ,george ,c4 ,marshall ,space ,flight ,center1 #ac1 #ag ,goldstone ,tracking ,station1 #fd1 #fg1 #fi1 #ge1 #hd1 #ajg ,echo site1 #fh1 #fi1 #ga1 #gc ,pioneer site1 #ef1 #fh1 #gj ,venus site1 #fi1 #gj1 #ajh1 #aji ,guidance1 #ac ,h ,high-energy radiation experiments1 #ij1 #ia ,i ,infrared radiometer experiment cloud observations1 #ajc1 #aje1 #ajf description1 #ic dimensions1 #ic operating characteristics1 #he1 #ic ,interplanetary magnetic field1 #ac1 #ii ,interplanetary space cosmic dust density1 #aaj distribution1 #ie hazards to spacecraft1 #ac ,ion chamber1 #ih ,j ,johannesburg tracking station1 #fg1 #fh equipment1 #fh1 #gc functions1 #fh1 #gc ,,jpl1 #b1 #h1 #ac1 #ge1 #gf1 #hj1 #hb1 #hd accomplishments1 #ah1 #ai background1 #ah ,,dsif control point1 #fg1 #fh pre-,mariner spacecraft1 #bc ,jupiter1 contrast to ,venus1 #aja ,jupiter ,c1 #ai ,l ,launch ,operations ,center1 #ab1 #ag ,launching1 #ef ,atlas performance1 #eb1 #ec ,atlas-,agena ,b1 #eb battery1 #eb gyroscopes1 #ec radio guidance system1 #eb time limitations1 #ab ,m ,magnetometer experiment1 #ce1 #hh data1 #aja1 #ajb description1 #ia function1 #ia objectives1 #ajj onboard location1 #ia ,mariner ,i1 #dc-de ,mariner ,r1 #da ,masers1 #gj ,materials1 thermal shielding1 #cc ,microwave radiometer experiment description1 #ia function1 #ia measurements1 #ajc1 #aje operating characteristics1 #he1 #ib-ic ,midcourse maneuver1 #cb1 #eh-ei1 #fj1 #fe ,mission achievements1 records1 #fe ,mobile tracking station1 #fh1 #hj location1 equipment and function1 #gc ,,mx-#ggd ,project1 #ba ,n ,,naca1 precursor of ,,nasa1 #af ,,nasa1 #h1 #af1 #ag ,p ,parking orbit1 #ee ,pioneer ,,iii1 #ai ,pioneer ,,iv1 #ai ,pioneer project1 #fi ,pioneer tracking site1 #gj1 #ga ,power system1 #be ,private ,a1 #ah ,propellants ,atlas ,d1 #ch attitude control system1 #cb spacecraft1 controlled burning1 #cb rocket thrust system1 #cb ,propulsion system1 ,mariner spacecraft1 hydrazine propellant1 #cc propellant storage1 #cb1 #ch weight1 #be ,r ,radiation1 #ih-ajj ,ranger ,,iii1 #h ,receivers1 #ff ,records1 ,mariner attitude control system1 #fe measurements near ,sun1 #fe operation near ,venus telemetry measurements1 distance1 #fe trajectory correction maneuver1 #fe transmission1 continuous performance1 #fe ,s ,sensors ,earth1 for attitude control1 #cb ,sun1 for attitude control1 #cb ,sergeant missile1 #ai ,shielding1 #cc1 #cd ,solar cells1 #bg1 #bh ,solar flares1 #ih1 #ii ,solar panels description1 #be design1 #bg output deterioration1 #fa release1 #aa support1 #be weight1 #bg ,solar plasma detector1 #ce1 #hh1 #if1 #ig description1 #hg1 #hi1 #ij function1 #hg1 #hi1 #ij recordings1 #if1 #ig ,solar plasma flux correlation with geomagnetic effects1 #ig ,solar wind effects on cosmic-ray movements1 #if magnetic fields1 #ie1 #if low density and energy1 #if measurement1 #hi particle concentration near ,earth1 #if particle energies1 #if temperature1 #if theories1 #ie velocities1 #ac1 #ie1 #if1 #ig1 #aaj ,space ,flight ,operations ,center1 #fj organization and operation1 #ge1 #hj1 #ha ,space simulator1 temperature control1 #da ,spacecraft1 #ca attitude control system1 #ca ,central ,computer and ,sequencer1 #bh components and subsystems1 #bg configuration1 #bc electronic equipment1 #be frame materials1 #bc1 #be launching1 #ab power system1 #be preliminary design1 #da propulsion system1 #cb shroud and adapter1 #dc system tests1 #da telecommunications subsystem1 #cj temperature1 #cc test models1 #da testing1 #bc trajectory1 #aa weight1 #be ,sun sensor1 #cb ,t ,telemetry continuous transmission1 #fe data processing1 #hd description1 #cj loss of monitoring data1 #fb phase-shift modulation1 #cj transmission cutoff1 #fd ,telemetry processing station1 #hb1 #hc ,telemetry system data processing1 #cj onboard1 description1 #cj ,temperature control coatings1 #cd heating problems1 #fb housing structures1 #ce materials1 #cc problems1 #cc solar panels1 #ce solar radiation shielding1 #ce thermal shielding1 #cc ,tracking ,antigua1 #ec ,ascension1 #ec1 #ee ,,dsif1 #eb1 #ff1 #fg1 #fh1 #fi ,earth noise1 #ff ,grand ,bahama ,island1 #ec ,johannesburg1 #ef ,pretoria1 #ec1 #ee problems1 #ff radio noise1 #ff ,san ,salvador1 #ec solar noise1 #ff ,twin ,falls ,victory1 #ec1 #ee ,whiskey1 #ee ,woomera1 #ef ,trajectory1 #aa1 #fc1 #fd1 #hc ,v ,v-#b rocket1 #ah ,van ,allen radiation belt1 #ai1 #ig ,venus atmosphere1 #c1 #e1 #ajd1 #aje1 #aab atmospheric temperature1 #he atmospheric winds1 #e ,,co content above clouds1 #ajf cloud cover1 #aje1 #ajf cloud observations1 #ajd1 #aje clouds1 data1 #aaa compared with ,earth1 #e description1 #d dielectric constant1 surface material1 #ajg encounter1 #ic1 #id historical data1 #b inferior and superior conjunctions1 #d magnetic field1 #ih1 #ajj1 #aaa comparison with geomagnetic1 #ajj1 #aja data1 #ajj1 #aja1 #ajb strength1 #ajj1 #aja1 #ajb mass1 #aji1 #aaa orbit1 #d radar experiments1 #aifa1 #ajf1 #ajg radar experiments during mission1 #ajg reflection coefficient1 #ajg revolution1 #d rotation1 #d1 #aja1 #ajh1 #aaa surface1 #ajf brightness temperature1 #ajc1 #ajd characteristics1 theories1 #ajb1 #ajc 8greenhouse0 effect1 #ajf measurements1 #ajc1 #ajd pressure1 #aab reflectivity1 #aaa roughness1 #ajg1 #ajh temperature1 #ajf1 #aaa temperature1 #he1 #aaa topography1 #e water vapor in atmosphere1 #ajf ,venus encounter1 #fc ,w ,,wac ,corporal1 #ah ,woomera ,tracking ,station1 #fg1 #fh1 #ge equipment1 #fh1 #ga1 #gc ,transcriber's ,notes --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,in the text versions only1 text in italics is delimited by underscores4 --,silently corrected a few typos4 --,in the index1 entry 8propellant storage01 replaced one nonsensical page number 7#bjj7 with a plausible conjecture 7#ch74