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Home , Pioneer 1, Pioneer 2, Pioneer 3, Pioneer 4

H UMAN F LIGHT &ROBOTIC E XPLORATION “Pioneering Space” Part II

By Gideon Marcus research determined that 108 had experi- days for and to be in similar enced the same problem. This discovery did respective positions again. The launch win- An Unnumbered Pioneer not come as a complete surprise. Dolph dows were so narrow that mission planners Just six months after Louis Dunn Thiel, propulsions expert at Space had long since decided to not provide trajec- gave the order to start production, through Technology Laboratories and Peenemünde tory compensation for launch holds. dint of hard effort and ingenuity, the first veteran, had noted early that year that Instead, each was preprogrammed Thor-Able three-stage booster towered 88 Thor’s turbopump design was thoroughly with a particular roll program, which varied feet above Launch Complex 17 pad A on marginal and recommended that the prob- depending on the launch day. The Air Force Merritt Island, Florida. The serial number, lem be fixed in the next run of the Thor mis- took for granted that the rocket would be 127, was printed on the Thor IRBM first sile. The problem was that several of the ready to fire at the proper time.2 stage, and USAF was proudly emblazoned potentially faulty Thors had already been Able-1’s first countdown went by along the Vanguard second stage. Atop the built and were committed for a variety of almost without a hitch. The Thor-Able third stage rested the world’s first lunar missions: several test flights, two more booster was fully fueled by the afternoon of probe. Roy Johnson, head of ARPA, and ARTV flights—and the Able-1 lunar 16 August. Engine and electrical checks U.S. Air Force Major General Bernard probes. were begun at 1930 and completed ahead of Schriever, who directed the first U.S. ICBM Should the Thor flights continue or schedule. On launch day, at T-35 minutes, programs, were among those in attendance. be suspended? That was the critical decision interstation communications were checked. The general was apprehensive about facing General Schriever. Fourteen Thors All stations reported that they were ready this flight and with good reason. In October had been launched thus far. Two had failed for operations, though the link to Singapore 1957, Thor 108 inexplicably exploded in in flight. Statistically, each Thor had a one- was somewhat noisy. mid-flight. Six months later, the first ARTV in-seven chance of exploding. Grounding At around the same time, telemetry Thor-Able blew up 146 seconds into its the Thor would cause several months of modulation of the Able-1’s low-frequency flight. This time, the malfunction was linked delay in a number of projects. On the other transmitter mysteriously ceased, the antenna to the Thor’s turbopump gearbox. Further hand, even in the event of the loss of one or instead locking on to a local, low-level two missiles, valuable guidance data could transmission. At T-15 minutes, a short hold be gathered. The only hard decision was called to turn off local telemetry involved the three Able-1 missions. General receivers in the hopes that they were attract- Schriever decided the odds were good ing the probe’s transmitter, but the problem enough, and ordered no delays, balancing persisted. The payload’s Doppler receiver the risk of a public relations disaster against did lock just fine when the local ground the benefits of accelerated development.1 transmitter was turned on. It was ultimately Seconds ticked by as the launch time concluded that there was some low level grew ever closer. The countdown was a “T- interfering signal unrelated to the transmit- minus” system with built in holds before the ters and receivers at the blockhouse. launch time as opposed to the older variety, Mission controllers ultimately decided that which pushed the launch forward with every the problem was not a large one and that it delay. This type of countdown is common- would likely correct itself after takeoff any- place now, but at the time this was a new way. No further problems were encountered innovation developed to accommodate mis- during the countdown and Thor 127’s sions with inflexible launch windows, lunar motors ignited at 0718 on August 17, four shots being among them. Hitting the vicini- minutes behind schedule.3 ty of the Moon from the rapidly spinning As America’s first lunar mission surface of Earth is a complicated billiard began its stately ascent from Pad 17-A, the shot. The opportunity to reach lunar orbit mood became jubilant. At 73.6 seconds comes only four days out of every month, later, elation turned to horror. The main and there is only a 35-minute window on bearing on the first stage’s turbopump, driv- Carl McIlwain Image courtesy of Gideon Marcus even the best of those days. If they missed en by the intense revolutions of the pump the window, the launch crew must wait 28 shaft, walked its way out of its housing and

Q U E S T 14:3 2007 18 tore Thor 127 pieces—the same disaster that restrial molecules might had befallen Thors 108 and 116. The mis- adversely affect life or pre- sion was over. General Schriever had lost life processes on the Moon his gamble. Dolph Thiel placed his head in was justification enough his hands and sobbed.4 for the precaution.7 The next flight was optimistically At the Cape, Dr. planned for mid-September. This date was George Mueller, director of pushed to mid-October, which among other the Able-1 project at STL, things gave Van Allen’s team time to com- and U.S. Air Force plete its ion counter experiment. Lieutenant Donald Latham directed launch operations, Flies their 40-person crew com- Two months after the failed flight of pleting readiness checks Able-1, Thor 130 stood ready on the pad. with all STL ground sta- Though President Dwight Eisenhower had tions the day before launch. created the National Air and Space In addition to the primary Administration on 29 July 29, and on 1 tracking stations at October 1958 the new agency officially Canaveral, Hawaii, took control of all civilian space missions, Singapore, Manchester, the Thor-Able booster still bore the letters and Millstone (NH), ten “USAF” on the second stage. Its payload, Vanguard Minitrack sta- however, did receive a new name. The tions in Peru, Antigua, Army’s series of satellites was called Chile, Ecuador, the “Explorer” and their public information Bahamas, South Africa, officer proudly proclaimed them the Texas, Havana, and “Pioneers in Space.” Stephen A. Saliga, Australia stood by to relay chief designer of Air Force exhibits at the tracking data through the Pioneer 0 launch assembly Image courtesy of Gideon Marcus Air Force Orientation Group, Wright- Cape.8 Preparations contin- Patterson AFB, suggested the Air Force ued right up to launch time. onds of fuel left in the second stage.11 At show who the real Pioneers in space were At one point, the Ramo-Wooldridge man in the time, no one knew what caused the first by naming the new lunar orbiter, charge of the Hawaii station reported that stage loft. Wind was suggested as the cul- “Pioneer.”5 His proposal was accepted, and the antenna there was frozen. Mueller prit,12 but the Air Force later concluded that under this new naming scheme, the Able-1 laconically replied that the man had 12 the problem was caused by the first-stage flying in October would be known to the hours to fix it, or they would launch any- autopilot.13 By third-stage burnout, some- world as “Pioneer 1.” In the interests of con- way. The antenna was repaired in time for thing was seriously amiss, though it took sistency, the failed August flight was desig- the launch.9 some time for the mission controllers to nated “Pioneer 0.” The countdown proceeded largely ascertain this. The velocity vector was off As with Pioneer 0, all concerned without incident. Ten seconds before dead- some 5 degrees now. Somehow the third felt great trepidation about the launch— line, there was a momentary hold: a super- stage had been cocked from center some 15 more so now that they’d already lost one of visor had not responded to one of many degrees after separation from the second their three . Unlike the August thumbs-up signals in the blockhouse. The stage. This deviation from the planned flight mission, Pioneer 1’s flight was a matter of countdown resumed a few seconds later path presaged failure for the spacecraft’s public scrutiny. If all went well, the space- with no further problems. At 4:42 a.m. east- primary mission. craft would be the world’s eighth space mis- ern daylight time, Saturday, 11 October As of third-stage burnout, Pioneer sion, America’s fifth, and the first to 1958, NASA’s first departed its was traveling at some 500 ft/sec less than approach the Moon, much less orbit it. All launch pad only 13 seconds behind sched- the desired 35,206 ft/sec, which would eyes on both sides of the Iron Curtain wait- ule.10 allow it to escape Earth’s gravity. All eight ed to see if America’s first civilian lunar Just 16 minutes later, all three stages vernier rockets, designed to keep the probe shot would be a success or not. Professor on the Thor Able had fired successfully. At on course, were fired to make up deficit. Van Allen, developer of Pioneer’s ion the shutdown of the first stage, the velocity Although they added some 160 feet per sec- counter, hedged his bet. “The success of the vector was some 2.5 degrees too high and ond to Pioneer 1’s speed, this was still far experiment does not depend on whether the the speed some 800 ft/sec above projec- short of the goal.14 At 10:15 a.m. EDT, the rocket hits, or even comes near the moon. tions. At second stage shutdown, Pioneer Pentagon released that tracking data was We will consider the flight a success if the was hurtling somewhere between 23,125 being received from Inglewood, Millstone, rocket reaches out 40,000 miles, let alone and 23,150 feet per second, which was actu- and Manchester, in addition to several 220,000 miles!” he declared.6 ally around 200 ft/sec below what it should Minitrack stations. However, they Before its flight, Pioneer 1 was have been. Pioneer was slightly off course, announced, it would not be clear whether or painstakingly sterilized with both a chemi- now suffering from three degrees of “loft” not Pioneer 1 was on course (albeit under cal bath and a torrent of ultraviolet. While or vertical displacement. Pioneer’s integrat- speed) until it could be seen by the Hawaii no evidence existed that the Moon bore any ed accelerometer thus cut off the engine pre- tracking station. At 11:45 a.m. EDT, the kind of life, the remote possibility that ter- maturely, despite there being some 10 sec- Pentagon reported that it appeared that

Q U E S T 14:3 2007 19 Pioneer 1 was departing from the intended the golden thumb.” The original mission did suggest that flux trajectory.15 plan had called for Stephenson to perform decreased with distance from Earth, the “Additional data and still further this duty some 2.61 days after launch as the impact count was so low that any meaning- analysis are required to determine the exact spacecraft reached the vicinity of the Moon ful statistical significance from their distri- trajectory of Pioneer,” they said. (though, in fact, an auto-detonator was also bution was impossible to determine. The huge tracking station at Jodrell installed to fire the rockets automatically During the flight, Pioneer 1 was Bank in England was the first to report that should his radio command have fail) exposed to the Epsilon Arietid meteor show- Pioneer 1’s velocity was insufficient for a Instead, per the USAF order, Stephenson er radiant. STL scientists had hoped that a lunar orbit, but it was still unclear whether sent the fire order less than one day after higher flux from this direction might serve or not Pioneer 1 might be saved in an eccen- liftoff. There was no response from Pioneer. as a kind of calibration and allow analysts to tric Earth orbit. Its course remained unchanged.22 see any directional variations in micromete- As of 10:47, Pioneer 1 had reached For two hours, the STL team attempt- oroid flux density. As it turned out, Pioneer 36,600 nautical miles above Earth, far high- ed to ignite Pioneer’s retrorockets to no recorded just one high momentum impact er than any artificial device had traveled avail. The spacecraft simply would not through the entire flight. It was impossible before. The Hawaii tracking station, not acknowledge the order. It was later deter- to deduce anything from that save for the scheduled to begin tracking Pioneer 1 until mined that the spacecraft’s low internal tem- tentative conclusion that there were not 1:00 p.m., came online shortly after noon. perature was to blame. Because of the dra- many high momentum in At 12:47 p.m. EDT, the craft was matic third-stage course deviation, the Sun’s cislunar space.26 some 45,300 nautical miles above Earth. At rays fell primarily on Pioneer’s unpainted 1:45 p.m. EDT, another statement was sections rather than on the spacecraft’s Ion Counter released. Hawaii had confirmed that Pioneer ingenious thermally regulating paint Pioneer 1 also dispelled concern 1 was still departing from its planned trajec- scheme. The frigid 36-degree internal tem- about the deadly belts of radiation discov- tory.17 Ominously, Pioneer 1 also reported peratures meant that the probe’s internal ered previously by Dr. Van Allen’s experi- that the internal temperature had settled at batteries simply could not generate enough ments on the Explorer satellites. The ion around 40 degrees Fahrenheit, far below current to receive instructions from Earth.21 counter, constructed by Van Allen’s team at what it was supposed to be. For the first Pioneer continued to send telemetry the University of Iowa, returned data from time in the history of the , data for the remainder of the flight, however, 3,500 km to 36,000 km above Earth and was reduced, analyzed, and released to the returning valuable engineering and experi- covered a latitude range of 35º N to 5º N. No public within hours. The world was kept mental data on the downward leg of is sub- data was sent below 3,500 km as the trans- apprised of Pioneer 1’s situation and find- orbital flight path, before plunging into the mitter was tied up for the first 17 minutes ings every step of the way via radio and atmosphere above the southern Pacific providing vehicle performance informa- newspaper. Ocean at 12:46 a.m. EST, Monday, 13 tion.27 Although initial findings were As Pioneer 1 ascended toward its October 1958.24 released almost immediately, the full analy- apogee, the spacecraft was ordered in the sis took a number of weeks and was a kind midafternoon to jettison the previously fired No Lunar Orbit, But a Triumph for of side-work for University of Iowa’s Carl vernier rockets so that the probe’s trajectory Sky Science McIlwain, whose primary focus was the could be more easily altered by its onboard Out of Pioneer’s four primary exper- study of aurora.28 Data was first presented retrorocket. At 5:45 p.m. EDT, the Air Force iments, only the Naval Ordinance Test in January 1959. The Journal of announced that it would try to fire the Station imaging system, whose activation Geophysical Studies received the finished fourth-stage engine to give Pioneer the was contingent on the firing of the probe’s article in late March, and it was published in “most scientifically useful path.”18 There retrorocket, failed to return any data. While May. was still hope that the TV camera might take Pioneer 1 did not reach its intended goal, the This article detailed an astonishing high-altitude pictures of Earth.19 As of 4:47 vicinity of the Moon, it still flew an order of discovery. Pioneer 1 had reported that the p.m. EDT, Pioneer had reached 56,500 nau- magnitude higher than any probe before it. level of ionizing radiation rose to a peak of tical miles in altitude. By 8:00 p.m. EDT, Its instruments took extensive measure- 10 roentgens/hour at 10,000 km and held at Pioneer was at 58,725 nautical miles, its ments from deep into cislunar space giving about 8 roentgens/hour up to 17,000 km. speed down to a few thousand feet per sec- the first glimpse of a truly exospheric envi- Above that altitude, however, the radiation ond. Shortly after, at 8:09 p.m., the station at ronment.25 level dropped steadily, eventually becoming Singapore began tracking Pioneer. With immeasurable above 29,000 km. This con- this, every station built or employed for the Micrometeoroid Detector firmed the trapped radiation surrounded purpose of communicating with the space- Pioneer’s micrometeoroid detector Earth in a finite band rather than extending craft had been engaged. Hawaii was also data put to rest any fears that menacing infinitely into space. These Van Allen Belts, still tracking at this point. clouds of dust posed a hazard to human as they came to be called, were no longer By 10:47 p.m. EDT, Pioneer had . The probe’s acoustic diaphragm considered an obstacle to crewed lunar mis- crept to 67,550 nautical miles.20 reported surprisingly few hits—just 11 low sions. Arrangements were made for the Hawaii momentum impacts were recorded in the Because Pioneer 1’s ion counter was station to order Pioneer’s retrorockets to fire first nine hours of flight. When a mean suspected of having a leaky tube (see at midnight.21 This task would fall onto velocity of 10,000 meters per second was “Pioneering Space, Part 1,” Quest: The Richard G. Stephenson of Rolling Hills, assumed for these particles, this came out to History of Space Flight Quarterly 14:2, head of STL’s space computing and tracking a measured density of just one micromete- 2007:52–59), there was some concern that section, hailed by the press as “the man with oroid per cubic kilometer. While the data its measurements were inaccurate. Four

Q U E S T 14:3 2007 20 similar chambers were evaluated than had been expected for that using the cobalt source at the height. There were two sources of UCLA Medical Center where potential error that might have scientists had calibrated the tube accounted for these results. The used on Pioneer. Two of the test- large dynamic range of the magne- ed tubes retained their pressur- tometer tended to increase absolute ization while the other two, error. Also the fluctuations in the known to have leaks, eventually data complicated determination of stabilized at an internal pressure a statistical mean. Still even when close to atmospheric. Most these factors were taken into con- important, it did not seem that sideration, the difference between outside air was getting in, which the measured and expected field would compromise the experi- strengths was outside the margin of ment. As the sensitivity of the error. One exciting interpretation of experiment was directly propor- these measurements was that tional to the argon pressure in the Pioneer had flown through the tube, it was a simple matter to boundary where Earth’s magnetic apply a constant correction to field interacted with the coronal Pioneer’s data based on its inter- wind emanating from the Sun, a nal pressure, projected to be 1.58 sort of geopause corresponding to atmospheres at launch. Of the heliopause where the solar course, if the tube had reached Above: Pioneer 1 assembly Image courtesy of Gideon Marcus wind interacts with galactic radia- Below: Pioneer 1 lift-off Image courtesy of Gideon Marcus equilibrium before launch, that is, tion.30 the tube had just one atmosphere The question raised by Pioneer’s of pressure, then the sensitivity of findings was whether or not the the instrument would have been probe had discovered a global phe- correspondingly reduced by nomenon or a local anomaly. In almost 50 percent. Therefore, support of the former, it was sug- there was the possibility that the gested that the deviation from the strength of the field was signifi- predicted field strength might have cantly underreported.29 Even if been due to an error in the assign- this were the case, the boundaries ment of the position of the geo- of the Van Allen Belt had been magnetic pole at high altitudes. clearly delineated and even a first But it was also possible that circu- order model of the distribution of lating currents produced an uneven ionized particles above Earth was distribution, and Pioneer had tremendously useful. Dr. Van encountered a more dense section Allen could confidently declare of the field. Finally it was possible the mission a success. that centrifugal forces acting on an ionized medium within the mag- netic field caused local increases in Of all Pioneer’s experi- the magnetic field density. Pioneer ments, it was the magnetometer 1’s data was insufficient to resolve that returned the most enigmatic the issue.31 results. Pioneer’s magnetometer In the end, Pioneer 1 raised more was designed to measure the questions than it answered. Further strength of the surrounding mag- missions were required to sort out netic field. As the spacecraft these mysteries. rotated, the instrument returned a signal that varied in a sinusoid Pioneer—The First fashion. The amplitude of the Communications Satellite magnetometer signal indicated Pioneer 1 was the first spacecraft the strength of the magnetic field. By com- Not only did the experiment corrobo- to fly high enough to test satellite communi- paring the relative phase of the magnetome- rate the findings of ground-based observato- cations relay technology. Telemetry was ter’s sinusoid with that of the spacecraft’s ries, it also discovered new magnetic phe- relayed through Pioneer from Cape radio signal, which would not be affected by nomena, particularly in the two hours the Canaveral to Manchester, England, and later external factors, analysts were able to indi- spacecraft spent at an altitude of about 10 from Hawaii to the Cape, and finally across rectly measure transient magnetic effects. Earth radii. Up to that point, the magnetic the world from Hawaii to Manchester. This Using this clever trick, Pioneer was able to fields Pioneer traversed had not deviated far experiment presaged the development of detect rotations of the magnetic intensity from the theoretical model derived from ter- geosynchronous communications satellites. vector and oscillations in its amplitude. restrial measurements. Above 80,000 km, Project Director George Mueller is credited the measured fields were distinctly stronger Q U E S T 14:3 2007 21 with the development of this experiment.32 reporting this information to NASA was experimental package was the Budd Cohen. Cohen had come to Ramo- proportional counter telescope. Through Improving on Success Wooldridge as a clerk. By October 1958, he balloon and sounding-rocket flights, it had Pioneer 2 was scheduled for launch at was manager of the Astrovehicles depart- become apparent that there was an indirect the next opportunity, just four weeks after ment at STL. As such, he was officially connection between solar activity and the the flight of Pioneer 1. Chuck Sonett and his responsible for the faulty design of the sec- overall level of cosmic rays. According to experiment team scrambled to put together a ond/third stage interface though he had not theory, the solar wind affected the magnetic package that could confirm and enhance personally been involved in its develop- fields around and beyond Earth, which in data collected on the last mission. At the ment. Before coming to STL, Cohen had turn created variations in the degree to same time, Mueller directed efforts to elim- worked for the National Advisory which entering cosmic rays were diffused. inate the issues that had marred the momen- Committee on Aeronautics under Abe John A. Simpson, an astrophysicist at the tous flight of Pioneer 1. Silverstein. On the eve of Cohen’s departure University of Chicago, was working on this What had caused the third stage to from the public service, Silverstein treated problem when the Pioneer mission was deflect so far off course? STL’s president, him to a diatribe against the evils of the pri- announced. Louis Dunn, at a press conference on 12 vate sector. “They’re all crooks!” he In May 1958, Simpson met with October, blamed the first-stage autopilot. declared, doing his best to dissuade Cohen Hugh Odishaw, executive director of the Some believed that the vernier rockets had from leaving. He left anyway. Several years U.S. National Committee for the contributed to the deviation.33 Others felt later, as luck would have it, the man Cohen International Geophysical Year, in that if the second stage had kept burning had to report his findings to was the brand Washington, DC. As it turned out, an acade- until it was out of fuel rather than cutting off new director of NASA’s Office of Space my meeting was being held the next day, at third-stage separation with ten seconds of Flight Programs, Abe Silverstein. This Odishaw informed Simpson, and that some fuel remaining, the craft would have unpleasant reunion seemed to confirm the ARPA people would be in attendance. reached orbital velocity.34 unfavorable view Dr. Silverstein had of Simpson rushed off to at the Cosmos Club, As it turned out, the cause of devia- commercial enterprise in general, and his an elite social club on Massachusetts tion was fundamental to the design of the department’s disdainful view of STL, Avenue, to prepare a draft proposal—using second stage. A support beam at the front of specifically.36 the back sides of club correspondence the stage had been mounted asymmetrically Several changes were made to paper! He presented it the next day, and offi- for perfectly sound engineering reasons. Pioneer 2 and the Thor-Able launch vehicle cial approval came on 27 May. This was When the third stage fired against the sec- based on the Pioneer 1 flight. There was no Simpson’s first space experiment, tentative- ond, this asymmetry deflected the thrust and time to redesign the second- to third-stage ly scheduled for launch on Pioneer 1.39 sent the booster careening off course. Even interface. Instead, to ensure that Pioneer 2 Simpson submitted a budget propos- though the third stage on Pioneer 1 went on did not suffer the same fatal course devia- al to the office of Homer Newell, chair of to perform within 5 percent of its predicted tions as Pioneer 1, engine cutoff was gov- the IGY satellite panel. Confirmation of performance, the damage had already been erned by a manual Doppler command trig- funding came on 16 June 1958. The con- done.35 Ten more seconds of second stage ger rather than the automatic accelerometer. struction team consisted of Simpson as prin- thrust probably would not have made a dif- A one-second delay between second-stage cipal investigator, Peter Meyer, a fellow ference. cutoff and third-stage ignition was intro- physicist at Chicago, and Charles Yun The man with the unenviable job of duced. Theoretically, these modifications Fan.40 would ensure that the third stage was well Dr. Fan had worked with Aden away from the second before firing and also Meinel on auroral physics for five years guarantee that the second stage was empty before deciding to accept a teaching posi- before separation.37 The number of spin tion at the University of Arkansas, which motors/verniers was increased from 8 to 12 was where he was when Simpson asked Fan not only to make sure Pioneer 2 was spun to to come to Chicago and assume responsibil- the proper rate of 2 revolutions per second, ity for the construction of a set of propor- but also to better correct for any deviations tional counters for the Pioneer 2 project. Dr. of the booster during flight. A second trans- Fan only expected to be away for the three mitter, operating at 100 milliwatts on months it would take to construct and 108.09 Mhz (as opposed to primary trans- implement the experiment. After arriving in mitter’s frequency of 108.06 Mhz), was Chicago, he found a way to significantly added so that telemetry could still be sent at improve the original design but it meant the same time the spacecraft received delaying the experiment until Pioneer 2.41 Doppler command signals. Finally, a more The actual device was composed of robust battery was installed so that the seven tubes, two inches in length, six of spacecraft would respond even if the tem- them arranged concentrically around the perature plunged below anticipated levels seventh and shielded in lead. The experi- once again.38 ment would tally cosmic rays entering the central tube in addition to events affecting An Updated Experiment Package the central tube and two diametrically oppo- Proportional Counter site outer tubes. Fan’s triple coincidence The most significant addition to the design, superior to the original double coin- Pioneer 2 lift-off Image courtesy of Gideon Marcus

Q U E S T 14:3 2007 22 STL graphic courtesy of Gideon Marcus cidence plan, would serve to help map the box. camera that utilized the two rps spin rate of radial distribution in the high flux above The test worked.43 the spacecraft along with a clever algorithm Earth and enable the telescope to better to dramatically reduce bandwidth needs. As complement the Iowa ion counter experi- STL Television the spacecraft spun, it would scan a 64- ment.42 Space for experiments was always at degree segment of its revolution, begun as Before sensitive experiments like the a premium on Pioneer. In order to make the optical beam crossed the limb of its tar- counter telescope could be cleared for room on the probe for the new telescope, get. Each of these scan lines was divided flight, the equipment had to be subjected to the original Navy-provided imager had to into 128 elements about 0.5 degree square, violent physical stress to ensure the devices be deleted without ever having returned a corresponding to the 0.5 degree wide opti- would withstand the flight into orbit. To this single pixel. A completely new system had cal aperture. One of the elements would be end, it was standard procedure to strap to be developed for the Pioneer 2 flight. sampled and then transmitted back to Earth experiments to a special table and subject STL engineers Charles Sonett, Stewart every time the spacecraft rotated. Each time them to a “shake test.” STL had a shake Baker, and John Kelso developed their own Pioneer 2 spun, the sampling began a touch table; the University of Chicago did not. design, one with limited capabilities but later to target the next element in the scan But Sonett’s team was in bad esteem with weighing only three pounds. line. With the probe’s rate of revolution, one NASA’s Space Science Board for alleged Like the Navy imager, the STL tele- degree of the Moon or Earth would be shoddy construction and calibration of vision used a mirror in an optical unit that imaged and returned. Thus, it would take experiments in addition to their rough and reflected intercepted light onto a photosen- 128 revolutions just to scan one 0.5 degree ready management of the contributing sci- sor, which would produce a voltage propor- wide line! But the system would only use entists. Simpson was unwilling to use STL’s tionate with the amplitude of the received the ridiculously tiny bandwidth amount of 1 facilities, and insisted on handling all beam. Pioneer 2’s TV, with its strict weight Hz.44 According to computer predictions, aspects of package development. Rather restrictions, lacked the heavy transmitter Pioneer had barely a 50 percent chance of than build or purchase their own shake and power supply that enabled the NOTS making a lunar orbital insertion at all, much table, his team hit on the idea of dropping camera to produce a continuous, though less in any specific orbit. Therefore, the their apparatus out of the third floor win- crude, image using a few kilohertz of band- STL TV was optimized based on a best- dow of their laboratory and into a toy sand- width. Instead, Sonett’s team designed a guess “average” orbit of around 6,700 km.

Q U E S T 14:3 2007 23 cussion.47 dropped dramatically as the booster attempted to light itself. The vernier rockets Magnetometer were then given command to fire but no The addition of a sec- effect was observed.52 ond telemetry transmitter had Pioneer 2 was tracked for about 15 immediate application in the minutes, reaching a maximum altitude of magnetometer experiment, 1,550 km and flying some 12,500 km before allowing monitoring of the burning up above Africa.53 Automatic Gain Control on the amplifier and the direct Shortened Flight Still Yields Results amplifier output. The experi- Despite the brevity of the Pioneer 2 ment could now more easily flight, the probe managed to return useful detect the transient phase and data. This was still a relatively high altitude amplitude changes first dis- mission and only the ninth shot into deep covered by Pioneer 1.48 space. Unfortunately, because the flight was so short and Earth was largely in darkness, The Able second stage Image courtesy of Gideon Marcus the much maligned TV camera missed the Flight of Pioneer 2 opportunity to take the first photograph of 54 At that range, the 0.5 degree scan lines Just a few weeks after Earth from outer space. The magnetome- would just touch. Further away, there would Pioneer 1’s historic flight, Thor 129 stood ter also failed to return useful data. be gaps between the scan lines. Any closer ready on the launch pad. The Thor-Able’s Corroboration of Pioneer 1’s exciting find- and there would be overlap. second stage, which had borne the letters ings at the fringes of Earth’s magnetic field At that distance, the lunar diameter “USAF”, had been hastily painted over with would have to wait. would subtend an angle of about 30 degrees white blankness.49 On 6 November, prelim- On the other hand, the micromete- and the resolution of an individual element inary readiness checks were completed. The orite diaphragm returned surprising results. was about 25 miles. The beam angle of the operations center was fully staffed at T-4 The instrument reported 20 strikes between camera was aimed some 135 degrees from hours.50 The launch was scheduled for early 1,200 and 1,430 km in altitude, and this was the nozzle end of the spin axis. On televi- on 7 November, but during the countdown, likely an incomplete record given that sion activation with the firing of Pioneer 2’s a valve in the pumping system between the ground tracking was intermittent during the retrorocket, the Moon would have presented tankage and combustion chamber of the first flight. This high flux during such a brief itself half full. If Pioneer 2 made it into stage engine became stuck. The prudent time contrasted sharply with the long, rela- orbit, the probe would be able to scan the decision was made to delay the launch one tively event-free Pioneer 1 mission. Sonett’s fully illuminated far side of the Moon and day, though as it turned out, the valve was team ventured the possibility that some kind obtain a good view of the half-illuminated repaired before the scheduled launch time.51 of gravitational or electromagnetic contain- Earth. It was not expected that the Sun’s Pioneer 2 launched at 2:30 a.m. EST, ment of this meteoric debris had caused the 55 rays would enter the acceptance cone of the just 31 seconds after its scheduled liftoff. As higher measured flux. optics unit at any time during the flight.45 of first stage cutoff, the booster’s velocity The ion counter also returned useful Sonett’s team used a GE photoflood was some 200 ft/second higher than nomi- data. While Pioneer 2 did not travel high light situated behind a Cupric Chloride filter nal, and the rocket was pointed 1.5 degrees enough to confirm Pioneer 1’s findings, the to calibrate the package. Then a double- lower, 2.3 degrees to the left of nominal. At probe instead served as a follow up to the sided mirror, revolving at one rps to simu- second stage cutoff, Pioneer 2 had reached a mission. Both Explorer 4 and late the rotation of the spacecraft, was then speed of around 27,000 feet/second and its Pioneer 2 used essentially the same experi- placed between the camera and a 39-inch flight path. Performance had been so good ment, so the two data sets were easily com- square test pattern. The camera was that it was still not certain how many pared. Analysts could assume that any dif- switched on and after two hours had verniers would need to be fired after third- ferences in ion flux could be attributed to returned a blocky but recognizable 128 by stage burnout. Sadly, it was a question that external factors such as altitude and geo- 128 facsimile.46 quickly became academic. graphic position. At an altitude of 1,550 km, No one was really happy with the On second-stage burnout, the spin Pioneer 2’s instruments ion count rate was performance of the camera. At one point, an rockets then fired and spun the rocket to a about 1,200 counts per second. According to angry Frank Lehan, deputy head of guid- satisfactory spin rate of 2.2 revolutions per Van Allen’s theory of trapped radiation, ance, collared Chuck Sonett in the STL second. The third stage separated properly, counting rates should be relatively inde- parking lot. “Why can’t you design a system but then it failed to ignite. Somehow it pendent of longitude but strongly dependent that would work?” he demanded. Two days failed to receive the firing command due to on geomagnetic latitude. STL engineers Al later, Sonett was summoned to the guidance a break in the wire to the igniter or a poor Rosen and Paul Coleman were fairly sure office and compelled to explain to his supe- connection, a failure in the internal firing that the Explorer 4 data for the same altitude riors why his camera was so limited. In the transmitter, or a failure in the igniter itself. and latitude would be comparable to end, little could be done. STL knew ahead Whatever the specific cause, somehow the Pioneer 2’s, despite any difference in longi- of time that the camera would do little more second/third stage separation broke the link tude between the two satellites. A call to than turn on and display black or white. But between the command receiver and the Carl McIlwain at Iowa State confirmed their Sonett’s camera was the only one which third-stage engine. Something went on in suspicion—the earlier satellite had indeed would fit on Pioneer, and that ended the dis- that crippled stage, however, as the spin rate recorded a similar count rate. Van Allen’s

Q U E S T 14:3 2007 24 model had been confirmed.56 proven Able with the more powerful Atlas 23 “Moon Rocket Streaks Back,” 1. While the ion chamber could return ICBM. 24 Aviation Weekly (20 October 1958):32. the average number of ionizing collisions, 25 STL, 1958 Volume 1, 14. About the Author giving information on the general radiation 26 C. P. Sonett, “Results of Pioneer 1 Flight,” 1958 level, the proportional counter telescope Gideon Marcus is a graduate of the NASA/USAF SPACE PROBES (ABLE-1) FINAL actually counted the number of fast particles University of California’s San Diego histo- REPORT, Volume 2 (Los Angeles: Space Technology hitting the instrument every second. ry department and a member of the AAS Laboratories, 1959), 43, 56. Combining the data sets from both experi- History Committee. This article marks the 27 Alan Rosen, Charles P. Sonett, Paul J. Coleman Jr., ments allowed analysts to discern the nature end of his initial three-part series on STL’s and Carl E. McIlwain, “Ionizing Radiation at Altitudes of the high energy particles detected by first space efforts. Ultimately, this series of 3,500 to 36,000 KM, Pioneer 1,” Journal of Geophysical Research 64, 7 (July 1959):709. Pioneer 2. It was determined that the high will detail the company’s space activities specific ionization, that is, average radiation through 1960. The author thanks Guy 28 Carl McIllwain, interviewed by Gideon Marcus, 3 December 2005. per particle, could not have been generated Garnett and Janice Marcus for the editing of by high energy electrons alone, but rather these articles as well as Stu Baker and Art 29 Rosen et al., “Ionizing Radiation,” 712. by a combination of electrons and pro- LeBrun for the use of their photographs. 30 STL, 1958 Volume 2, 82, 85. tons.57 31 STL, 1958 Volume 2, 80. STL, 1958 Volume 1, 27. The author’s previous articles on Pioneer 32 “Hawaii Sent Messages to Britain via Moon Rocket, Aftermath appeared in Quest, volumes 13:4 and 14:2. General Reveals,” Los Angeles Times, (17 October It was a disappointing end to one of 1958), 1, 31. the most ambitious projects of the early 33 Aviation Weekly (27 October 1958). Notes space age. From inception to final launch, 34 “U.S. Rocket Rising 80,000 Miles,” 1, 56. less than one year had elapsed. The booster 1 Julian Hartt, The Mighty Thor (New York: Van Rees Press, 1961), 166–69. 35 STL, 1958 Volume 2, 83. developed for Pioneer went on to be one of 36 Budd Cohen, interviewed by Gideon Marcus, 1 the nation’s most used workhorses. Pioneer 2 Space Technology Laboratories (STL), 1958 NASA/USAF SPACE PROBES (ABLE-1) FINAL February 2006. 1 itself smashed all previous altitude REPORT, Volume 3 (Los Angeles: STL, 1959), 14. 37 STL, 1958 Volume 2, 83. records and returned unprecedented scien- 3 STL, 1958 Volume 3, 119–20. tific information about conditions in deep 38 Aviation Weekly (17 November 1958):30. space. And yet, despite all the positive spin 4 Hartt, The Mighty Thor, 199. 39 See http://www.hq.nasa.gov/office/pao/History/SP- her builders and the Air Force put on the 5 “Origins of NASA Names,” http://history.nasa.gov/ 4215/ch1-3.html. Accessed 30 May 2007. SP-4402/SP-4402.htm. Accessed 16 October 2006. Pioneer flights, they failed in their primary 40 See http://www.hq.nasa.gov/office/pao/History/SP- goal—to reach the Moon before the Soviets. 6 State University of Iowa News and Information 4215/ch1-3.html. Accessed 30 May 2007. Service, 11 October 1958, 30. With the completion of the Air Force proj- 41 See http://lasr.happyones.com/CML-LASR-recollec- ect, it was now up to the Army to carry the 7 “Rocket Sterilized to Guard Later Research,” Los tions.htm. Accessed 9 January 2007 (e-mail May 2002). Angeles Times (12 October 1958), 1. torch with its two scheduled flights. 42 STL, 1958 Volume 2, 45. Sadly for American prestige, the 8 “Inglewood Lab Tracking Rocket,” Los Angeles Times 43 C. Y. fan e-mail 16 March 2006. See http:// (11 October 1958), 4. December shot of was a bust, too, www.hq.nasa.gov/office/pao/History/SP-4215/ch4- though the little probe set the new altitude 9 Richard Booton, interviewed by Gideon Marcus, 10 2.html. Accessed 30 May 2007. October 2006. record of 107,400 km. , the last 44 Stuart Baker, Television System Final Report Pioneer ARPA-commissioned lunar flight, launched 10 “U.S. Rocket Rising 80,000 Miles But will Not II (Los Angeles: STL Electronics Laboratory, 10 Circle the Moon; May Be in Orbit around Earth,” New December 1958). in March 1959, managed a distant of York Times (12 October 1958), 1. the Moon, but the Americans had already 45 Baker, Television System Final Report Pioneer II, 5. 11 Space Technology Laboratories, 1958 NASA/USAF 46 Baker, Television System Final Report Pioneer II. been beaten. On 2 January 1959, , a SPACE PROBES (ABLE-1) FINAL REPORT, Volume 1. Soviet probe almost 20 times heavier than (Los Angeles: STL, 1959), 82. 47 Chuck Sonett, interviewed by Gideon Marcus, 8 March 2006. Pioneer 1, had cruised just 3,995 km above 12 “Moon Rocket Streaks Back, Burns over Sea,” Los the surface of the Moon. Angeles Times (13 October 1958), 2. 48 STL, 1958 Volume 2, 61. In the end, the Soviet victory in the 13 STL, 1958 Volume 1, 82. 49 Paul Coleman, interviewed by Gideon Marcus, 8 second round of the space race only served October 2006. 14 STL, 1958 Volume 1, 83. to spur the American lunar program. STL 50 STL, 1958 Volume 1, 77. quickly lobbied for and won the contract for 15 “The Pentagon’s Official Statements on Progress of Lunar Vehicle,” New York Times (12 October 1958), 56. 51 Aviation Weekly (17 November 1958):30. a new lunar orbiter, one that dwarfed its 52 STL, 1958 Volume 3, 144–45. original efforts and would show up the 16 “Rocket to Fall Short of Moon Goal,” Los Angeles Times (12 October 1958), 1. Russians in a big way. The new probe would 53 Aviation Weekly (17 November 1958):30. also be called Pioneer, a name that would 17 “The Pentagon’s Official Statements,” 56. 54 Baker, Television System Final Report Pioneer II, 38. become virtually synonymous with STL 18 “The Pentagon’s Official Statements,” 56. 55 STL, 1958 Volume 2, 56. (and its parent company, TRW) throughout 19 “Rocket to Fall Short of Moon Goal,” 1. 56 A. Rosen, P. J. Coleman Jr., and C. P. Sonett, Ionizing the 1960s. A new booster was required to 20 “The Pentagon’s Official Statements,” 56. Radiation Detected by Pioneer II, Planet Space Sci. launch such a heavy spacecraft. Since the Volume 1 (Great Britain: Pergamon 21 “U.S. Rocket Rising 80,000 Miles,” 56. Thor-Able fusion had been such a success, Press, 1969), 343–46. the new rocket would be the mating of the 22 “Southland Leads in Lunar Probe,” Los Angeles Times (11 October 1958), 3. 57 STL, 1958 Volume 2, 48.

Q U E S T 14:3 2007 25 UEST AGAZINE Top: Joseph P. Allen, STS-5 mission specialist, lets a spot-meter float Q M free during a period devoted to out the window photographs of the P.O. Box 5752 Earth from the orbiting Columbia. Allen is on the flight deck positioned Bethesda, MD 20824-5752 behind the pilot's station. United States of America Bottom: Pioneer 0 Liftoff.