Category Paving the Way for Apollo 11

There was eagerness for the final Block II to provide close-up pictures and radar reflectivity of the Moon’s surface, as well as (hopefully) seismometry. Ranger 5 had been scheduled for June 1962, but was postponed to allow the first pair of Mariner interplanetary missions to be dispatched in July and August.

On 30 August Rolph Hastrup, in charge of sterilisation, recommended that heat – treatment not be applied to the Block III. The use of ‘clean rooms’ to assemble the spacecraft, and the infusion of gaseous ethylene oxide to sterilise it within the Agena shroud shortly prior to launch should be continued. Clifford Cummings postponed a decision until after the next mission.

Ranger 5 arrived at the Cape on 27 August. As a result of recent modifications, it was about 10 kg heavier than its predecessors. The countdown on 16 October was scrubbed when a short circuit occurred in the spacecraft’s radio system. A launch the next day was ruled out by high winds. The mission got underway at 18:00 GMT on 18 October. Despite suffering a glitch, the Atlas responded to steering commands from the Cape, and the Agena achieved the desired parking orbit. This time, tracking ships were stationed in the Atlantic in order to provide continuous monitoring of the spacecraft’s telemetry. It had been decided that if the trajectory from the Agena’s second burn were to be beyond the spacecraft’s ability to correct, then the scientific priority would be to obtain gamma-ray data, rather than to snap flyby pictures of the Moon. This was because the Block III would provide TV, whereas there would be no gamma-ray spectrometers on any spacecraft that would head into deep space any time soon. The Agena made the translunar injection and released its payload. For the first time, the Deep Space Instrumentation Facility had two missions to keep track of in space. Mariner 2 was cruising to Venus, but the lunar mission would have priority call on resources during its 3-day flight.

When the Woomera tracking station acquired Ranger 5, it had deployed its solar panels and locked onto the Sun. The next task was to roll in order to acquire Earth as the second point of reference. But the temperature in the power switching and logic module of the computer/sequencer rose sharply and power from the solar panels was lost – there had been a short circuit. Patrick Rygh had replaced Marshall Johnson in charge of the Space Flight Operations Center, to free Johnson to manage the design and construction of the new Space Flight Operations Facility. James Burke, at the Cape, directed Rygh to have the spacecraft make a midcourse manoeuvre before its battery expired, to ensure that it would hit the Moon. But because the spacecraft had not acquired Earth its actual orientation in space was indeterminate. It was therefore decided to set up the manoeuvre using only the Sun as a reference. A command was uplinked to gimbal the high-gain antenna away from the nozzle of the engine on the base of the bus. The spacecraft initiated the ad hoc 30- minute manoeuvre sequence, but before it could be completed the transmitter fell silent. It appeared that electrical shorts had drained the battery. The Moon was ‘last quarter’ on 20 October. The inert vehicle flew by the trailing limb on 21 October at an altitude of 720 km and passed on into solar orbit – its progress once again being tracked by the transmitter in the surface package.

On 22 October W. H. Pickering ordered an investigation staffed by JPL personnel who were not involved in the project. When this issued its report on 13 November, it lamented that the mass limit imposed on the Block II prevented it from having any redundancy – in order to achieve its mission, the spacecraft required every system to

work. Burke was criticised for (in the opinion of people not involved) having spent too much of his time on launch vehicles, launch operations and space experiments, as opposed to the spacecraft. Burke was also criticised for the importance he gave to meeting schedules. However, in this he had merely been reflecting NASA’s desire to get ahead of the Soviets within the 36 months that had been assigned to the project. The structure of JPL was also criticised, in that engineers assigned to work on flight projects by the technical divisions often lacked vital experience, and section chiefs unfamiliar with either the project management or the subsystems that their engineers worked on had inadequately reviewed this work. Remarkably, despite the fact that a lack of commonality in the failures implied a reliability issue in the components, the investigation did not address the issue of heat sterilisation, and Hastrup’s memo to Cummings was not discussed. The report concluded that the Block III was unlikely to perform any better. To remedy the situation, it recommended (in part) that Burke be replaced and that his successor review the Block III design, add redundancy, and introduce new project management, inspection and testing procedures.

Neither of the two Block Is had achieved the intended high-apogee orbits (owing to Agena problems) and only one of the three Block Ils had reached the Moon (in an inert state). The project had been acknowledged to be technologically risky when it was commissioned, but no one had expected such poor performance. The spacecraft failures undoubtedly resulted from heat-sterilisation. The only scientific result from the entire exercise was provided by the gamma-ray spectrometer of Ranger 3, which established the existence of ‘hard’ radiation in space. However, absolutely nothing had been learned about the Moon. Nevertheless, the sense of ‘crisis’ would not have come about if the final Block II mission had been a complete success.

Responding to the mood, Homer Newell asked Oran Nicks to establish a Board of Inquiry to review the past performance and future prospects of the Ranger project. It was chaired by Albert J. Kelley, Director of the Electronics and Control Division of the Office of Advanced Research and Technology, and drew its membership from headquarters, field centres not involved in the project, and analysts from Bellcomm Incorporated – a systems engineering group established by the American Telephone & Telegraph Company in March 1962 at the request of the Office of Manned Space Flight to conduct independent analyses in support of Apollo. In particular, it was to submit recommendations ‘‘necessary to achieve successful Ranger operation’’. No thought was given to cancelling the project, because the high-resolution TV from the Block III was required for Apollo. On 30 November the Board issued its report. As regards JPL, it said that because the laboratory was attempting to use a common bus for its lunar and planetary projects, Ranger was more complex than strictly required, and as yet the high order of engineering skill and fabrication technology required for this not to represent an issue had yet to be achieved. It also said that the degree of ground testing was inadequate – the laboratory’s tradition with military missiles was to iron out problems by test flights; this was impractical with spacecraft. The Board judged heat sterilisation to have been a significant factor in the failure rate. Of course, the lack of redundancy in the spacecraft was criticised. JPL was also criticised for trying to run such a major venture simply by superimposing a small project office on top of its divisional structure. The recommendations therefore included strengthening the project office at JPL and revising the procedures for design review, design change control, testing and quality assurance. Heat sterilisation should cease. The Block III objectives should be restated, and all activities which did not directly contribute put aside. If additional versions of the spacecraft were required, then JPL should hire an industrial contractor.

On 7 December 1962 JPL relieved both Clifford Cummings and James Burke of their posts. On 12 December, Brian Sparks, Deputy Director of the laboratory, led a delegation to Washington to discuss the Kelley report with Homer Newell. At this and a second meeting on 17 December it was decided (in part) to delete the eight particles and fields experiments which Newell had added to the Block III in March; to discontinue heat sterilisation and the use of gaseous ethylene oxide; to discard all heat-treated hardware; and that (as originally intended) the sole goal of the Block III would be to obtain high-resolution TV of the lunar surface in support of Apollo. On 21 January 1963 William Cunningham, the Ranger Program Chief at headquarters, told the scientists that their experiments had been deleted from the Block III and, to ease the blow, pointed out that they would be favourably considered for carriage on possible future missions.

Morale at JPL was boosted on 14 December 1962 when Mariner 2 made a close flyby of Venus and became the first deep-space mission to make in-situ observations of another planet, along the way establishing that the solar wind was ‘gusty’.

On 18 December Robert Parks superseded Cummings, and Harris Schurmeier was made Ranger Project Manager – having been Chief of the Systems Division that had handled most of the work, he was the obvious choice. He immediately instituted a Ranger System Design Review Board involving Burke (who remained on the project staff), Gordon Kautz, Allen Wolfe and section chiefs of the supporting engineering divisions. Its primary task was to increase reliability by identifying and eliminating potential weak points in subsystems. The deletion of the experiments from the Block III released 22.5 kg of mass to accommodate redundancy. The enlarged solar panels were retained to provide a healthy power margin. Meanwhile, Bernard P. Miller of the Radio Corporation of America held a thorough review of the high-resolution TV package and recommended that the various wide-angle and narrow-angle cameras, together with their associated electronic assemblies, be split into two independent electrical chains so as to ensure that some pictures would be obtained even if an electrical problem were to disable one chain. Furthermore, to guard against the failure of the computer/sequencer, Miller recommended that a backup timer be added to start the TV system. Schurmeier accepted these recommendations. He also duplicated the gas supply of the attitude control system, and increased the capability of the main engine to make the Block III better able to correct a discrepancy in the translunar injection. And as arcing discharges were the single most worrisome cause of in-flight failures, he ordered that plastic covers be placed over all exposed terminals. W. H. Pickering strengthened the project office by revising the lines of authority and responsibility within the technical divisions so as to make the section chiefs personally involved in project activities, accountable for the quality of their engineers’ work, and no longer able to reassign personnel without the consent of the project manager. Pickering also made Ranger the laboratory’s highest priority flight project – thereby guaranteeing Schurmeier the authority he needed (and Burke had lacked) to drive work through in the manner desired. On 13 February 1963 NASA approved the long list of changes to be made to the Block III. In October the schedule for Block III was set, calling for missions in late January, March, May and July 1964.

Surveyor 4 was similar to Surveyor 3, with a soil mechanics surface sampler, but it also had a magnet on foot pad no. 2 to investigate whether there were magnetic particles in the surface material. It was to employ the last of the single-burn Centaur stages and fly essentially the same direct ascent trajectory as Surveyor 2 to aim for Sinus Medii. It lifted off from Pad 36A at 11:53:29 GMT on 14 July 1967. Both the Atlas and the Centaur performed satisfactorily, with translunar injection at 12:04:57. The spacecraft deployed its legs and omni-directional antenna booms, and, on being released, cancelled the inherited rates, acquired the Sun and deployed its solar panel. When commanded to acquire Canopus some 6 hours later, it did so without incident. It was decided to postpone the midcourse manoeuvre from the nominal 15 hours into the flight, and make it 24 hours later. The 10.5-second burn at 02:30:04 on 16 July imparted a change in velocity of 33.78 ft/sec to trim the initial divergence of 175 km from the centre of the 60-km-diameter target circle to a mere 8.5 km.

The pre-retro manoeuvre in which the spacecraft departed from its cruise attitude involved starting a roll of + 80.4 degrees at 01:24:44 on 17 July and a yaw of + 92.7 degrees at 01:29:34. This aligned the thrust axis with the velocity vector as that would be at retro ignition. The roll of -25.3 degrees at 01:35:05 was to optimise the illumination for post-landing imaging of crushable block no. 3. A landing on the prime meridian involved making an approach at 31.5 degrees to local vertical, as opposed to 23.6 degrees for Surveyor 3 at 23°W and 6.1 degrees for Surveyor 1 at 43°W. This would require a greater gravity turn in the vernier phase to force the trajectory to vertical. If successful, this mission would ‘open the door’ to sending future landers to targets in the eastern portion of the Apollo zone.

The altitude marking radar was enabled at 02:00:17, and issued its 100-km slant – range mark at 02:01:56.080. The programmed delay to the initiation of the braking manoeuvre was 2.725 seconds. The verniers ignited precisely on time, and the retro – rocket 1.1 seconds later – at which time the vehicle was travelling at 8,606 ft/sec. With everything apparently normal, the downlink fell silent at 02:02:41.018, when 40.9 seconds into the predicted 42.5-second duration of the retro-rocket’s burn. The vehicle was at an altitude of 49,420 feet, travelling at 1,092 ft/sec, and nominally 2 minutes

Outcome unknown 315

20 seconds from landing. The Deep Space Network was unable to re-establish contact with it.

The engineering team that studied the telemetry realised that whatever the fault was, it had cut the downlink within an interval of 0.25 millisecond without showing any indication in the preceding telemetry. The cause of the failure was not apparent. The only noteworthy unusual development was a slight modulation in the thrust of verniers no. 1 and 2, but it was not evident how this could have been relevant. The investigation listed four possible causes, without rating them in order of likelihood: (1) the breakage of a critical power lead in a wiring harness, or the failure of an

electrical connector, or the failure of a solder joint; (2) damage to the spacecraft’s circuitry from the rupture of the casing of the retro-rocket; (3) a transmitter failure; or (4) damage to the spacecraft’s circuitry caused by the rupture of a pressure vessel such as a shock absorber or a helium tank, nitrogen tank or vernier propellant tank. Since there was judged to be a “relatively low probability’’ of any of these failure modes recurring, no hardware changes were ordered.

Interestingly, if Surveyor 4’s problem was simply a transmitter failure, then it is highly likely that the vehicle landed safely.

Explorer 1 restored national honour, but the Department of Defense was deeply concerned that the Soviet launch vehicle was so much more powerful than its own. On 7 February 1958 President Eisenhower created the Advanced Research Projects Agency headed by Roy W. Johnson, who would report directly to the Secretary of Defense. Its was to develop national goals and coordinate, but not itself conduct, the necessary research.

On 21 October 1957, three weeks after the launch of Sputnik, W. H. Pickering, since 1954 Director of the Jet Propulsion Laboratory (JPL) in Pasadena, California, had proposed that a spin-stabilised probe be launched towards the Moon, possibly as soon as June 1958.2 The purpose of this Project Red Socks would be to produce “a significant technological advance over the Soviet Union” that would enable America to “regain its stature in the eyes of the world”. The Pentagon sent the proposal to Roy Johnson, who was eager “to surpass the Soviet Union in any way possible”. The fact that the Soviets had not yet announced a lunar flight prompted him to accept the challenge of America being the first to do so. Neil H. McElroy, who had superseded Charles Wilson as Secretary of Defense just a few days before the Soviets launched Sputnik, announced on 27 March 1958 the US decision to “determine our capability of exploring space in the vicinity of the Moon, to obtain useful data concerning the Moon, and provide a close look at the Moon”. It would be undertaken as part of America’s contribution to the International Geophysical Year.

The project was named Pioneer. To pre-empt calls for it to be assigned to one or other of the services, the Air Force and Army were to work in parallel on their own contributions. The Air Force would modify its Thor missile to use the upper stages made for Vanguard. Meanwhile, the Army, just as it had used the Jupiter-C variant of the Redstone in a configuration named Juno I to launch Explorer 1, would fit its Jupiter missile with upper stages by clustering solid rockets to create the Juno II. As conceived, there would be five flight opportunities: three for the Air Force and two for the Army.

The Air Force assigned the technical direction of its part of the project, including the provision of the payload, to the Space Technology Laboratories of Redondo Beach, California. This company served as the contract manager for the Air Force’s ballistic missile program. The plan was for the launch vehicle to undertake a ‘direct ascent’ from Earth and release the probe on a trajectory that would enable it to enter orbit around the Moon. The design of the probe was finished in June 1958, just three months after the project was given the go-ahead. It comprised a pair of squat cones with their bases on a short cylindrical section. The body was 74 cm in diameter and 46 cm tall. It was to be spun at 200 rpm for stability. The mass of 38 kg included the solid-fuelled retro-rocket to brake into lunar orbit and 18 kg of scientific payload. The Advanced Research Projects Agency stipulated that the probe have an imaging system, but the scientists considered the primary payload to be their instruments to follow up the discovery by Explorer 1 of charged-particle radiation near Earth, and in this case the ‘particles and fields’ instruments were a magnetometer to measure magnetic fields in cislunar space and a micrometeoroid impact counter.

At 12:18 GMT on 17 August 1958 the Thor-Able lifted off from Pad 17A at Cape Canaveral, but the seizure of a turbopump bearing 77 seconds later brought the

flight to a premature end. Intended to be named Pioneer 1, this inauspicious start entered the history books as Pioneer 0.

Meanwhile, Lyndon Johnson began to argue for a new government agency to run a major space program – it featured in a speech he gave in January 1958 in which he ‘signalled’ his intention to seek the party’s nomination to run for the presidency in I960.

As Eisenhower’s Special Assistant for Science and Technology, James R. Killian chaired the President’s Science Advisory Committee. This reported ‘‘space’’ to be ‘‘inevitable’’, citing as reasons: (1) defence implications, (2) national prestige, and (3) opportunities for scientific research. The Committee warned that if the Pentagon was allowed to run a ‘national’ program, grandiose proposals would jeopardise the scientific work. It would be better to organise the scientific program independently of the military. The Committee recommended assigning it to a body modelled on the National Advisory Council for Aeronautics, which had been established in 1915 to coordinate aeronautical research. On 2 April 1958 Eisenhower signed an executive order calling for the National Advisory Council for Aeronautics to be subsumed into the National Aeronautics and Space Administration (NASA) in order to manage the national civilian space program. He also created the National Aeronautics and Space Board to advise on policy. The National Aeronautics and Space Act was passed by Congress on 16 July, and signed into law on 29 July. The new agency inherited all of its predecessor’s facilities: the Langley Aeronautical Laboratory at Langley Field, which had been established in Hampton, Virginia, in 1917, together with its Pilotless Aircraft Research Station at Wallops Island; the Ames Aeronautical Laboratory at Moffett Field, established in 1939 in Mountain View, California; the Lewis Flight Propulsion Laboratory, which was established in 1941 in Cleveland, Ohio; and the High-Speed Flight Station, established in 1949 at Muroc Field in the high desert of California and renamed Edwards Air Force Base in 1950.[6] Although NASA’s remit

was much broader than that of its predecessor, it did not immediately gain control of the rocketry expertise at either JPL or the Army Ballistic Missile Agency.[7]

On 8 August Thomas Keith Glennan, for the last decade President of the Case Institute of Technology in Cleveland, Ohio, was nominated as NASA Adminis­trator. Hugh Latimer Dryden, Director of the National Advisory Council for Aeronautics since 1947, was to provide continuity by serving as his deputy. Congress confirmed the appointments within days. When NASA became operational on 1 October 1958, it inherited the Pioneer project from the Advanced Research Projects Agency.

The Air Force’s second probe rose from Pad 17A at 08:32 GMT on 11 October. The Thor performed flawlessly, but a guidance error caused the second stage to shut down prematurely. The third stage took over, but was incapable of making up the 250-m/s shortfall in velocity. Pioneer 1 was successfully released, but upon attaining an altitude of 115,350 km, about one-third of the way to the Moon, it fell back and burned up in the atmosphere on 13 October. The trajectory precluded the electronic TV imager from viewing the Moon. The scientists welcomed the data provided by the magnetometer and micrometeoroid detector. This flight also had an ion chamber supplied by James van Allen, but it developed a leak and the data was difficult to interpret.

The scientists augmented the third probe with a proportional counter supplied by the University of Chicago. The Thor-Able lifted off at 07:30 GMT on 8 November 1958. The first two stages worked, but the engine of the third stage failed to ignite. The trajectory of Pioneer 2 peaked at an altitude of only 1,550 km and it fell back into the atmosphere 6.8 hours after launch, having returned no significant data.

The Army’s probe was developed by JPL, which had supplied Explorer 1. It was a cone mated at its base to a cylindrical section, stood 51 cm tall and had a maximum diameter of 24 cm. Whereas the Air Force had used an optical-electronic sensor that scanned as the probe rotated, JPL designed a camera whose film would be wet – developed, scanned optically and transmitted to Earth for reproduction by facsimile methods. The image was to be taken from a lunar altitude of 24,000 km, with the shutter being triggered when a photocell noted the presence of the Moon in its field of view. The first flight was to test this sensor. Its successor would carry the entire camera and loop around the back of the Moon to take a picture of the mysterious far-side at a resolution of 32 km. However, when studies by Explorers 3 and 4 revealed that the charged-particle radiation in the Earth’s vicinity would ‘fog’ the film of the Moon-bound probe, the Army cancelled the film camera in August 1958

in favour of the development of a lightweight slow-scan TV camera and a magnetic tape recorder to store the image for transmission.

A Juno II launched Pioneer 3 from Pad 5 at 05:45 GMT on 6 December 1958. The probe was intended to make a direct ascent, fly close to the Moon and pass into solar orbit. But the Jupiter first stage shut down prematurely, and the upper stages were unable to make up the 286-m/s shortfall in velocity. The 6-kg probe peaked at an altitude of 102,300 km, fell back and burned up 38 hours 6 minutes after launch. Nevertheless, it produced useful data. In place of the camera, it had a pair of Geiger – Mueller tubes supplied by James van Allen to measure radiation in cislunar space, and these revealed the existence of a second zone of radiation some distance above the one already identified: the intensity peaked at 5,000 km and again at 16,000 km, then diminished to the probe’s peak altitude. At van Allen’s suggestion, the imaging system was deleted from the second probe to enable his instrument to fly again. In addition, lead shielding was installed on one of the Geiger-Mueller tubes to screen out the low-energy charged particles. With the imaging cancelled, the trajectory was revised from a loop around the back of the Moon to a flyby into solar orbit – as had been intended for the first probe. After lifting off at 05:45 GMT on 3 March 1959, Pioneer 4 successfully flew by the Moon at 22:25 on 4 March. Unfortunately, the range of 60,500 km was twice that planned, with the result that the photocell test

failed – but as there was no follow-up probe available to carry the camera this was of little consequence. The Geiger-Mueller results provided further support for the hypothesis that the Earth’s magnetic field traps charged particles that originate from the Sun.5

The idea of streams of particles flowing outward from the Sun was first suggested by British astronomer Richard C. Carrington. In 1859 he made the first observation of what would later be named a solar flare. The occurrence of a geomagnetic storm the following day prompted him to suspect a connection. In the 1950s the German scientist Ludwig Biermann cited the fact that the tail of a comet always points away from the Sun irrespective of the comet’s direction of travel, as evidence that the Sun emits particles. In 1958 Eugene Parker in America postulated a supersonic flow of high-energy charged particles, primarily protons and electrons, streaming from the corona in the form of a ‘solar wind’. The presence of charged particles circulating in the Earth’s magnetic field strongly supported this hypothesis.

Assembly of the first Block III began on 1 July 1963. The Radio Corporation of America delivered the high-resolution TV subsystem on 15 August. At 366 kg, the spacecraft was about 25 kg heavier than its immediate predecessor. On 6 December W. H. Pickering suggested to Homer Newell that NASA appoint a small group for an independent assessment of Ranger 6, which had just completed its pre­acceptance testing. Newell sent some members of the Kelley Board, with William Cunningham (Program Chief) and Walter Jakobowski (Program Engineer) representing the Office of Space Sciences and Applications. After being accepted, the spacecraft left JPL by truck on 19 December and arrived at the Cape on 23 December.

As the Block III did not have a surface capsule, it could tolerate a lateral velocity component in its terminal dive, but at the expense of smearing in the final images – those of greatest interest to Apollo. The launch window for Ranger 6 was 30 January to 6 February 1964. The Moon was ‘full’ on 28 January and would be ‘last quarter’ on 5 February. The target longitude would vary with the date of launch, migrating westward with the evening terminator. The constraints on latitude were less strict, but the Apollo planners were primarily interested in the equatorial maria. The target for a launch at the start of the window was in the equatorial zone 15 degrees east of the lunar meridian, in Mare Tranquillitatis.

The countdown started in the morning darkness of 30 January, and ran smoothly to liftoff at 15:49 GMT. The Atlas delivered a flawless performance. The Agena made translunar injection as planned. The only anomaly was about 2 minutes after launch, when the spacecraft’s telemetry showed that the TV subsystem had switched on for a period of 67 seconds. When Johannesburg picked up Ranger 6, it was on its way to the Moon and gave every appearance of being healthy. After locking onto the Sun and Earth, it deployed its high-gain antenna. A small midcourse manoeuvre was

made on 31 January. “I’m cautiously optimistic,” Pickering told reporters at a press conference shortly after the manoeuvre.

As Ranger 6 neared the Moon on 2 February, it was accelerated by that body’s gravity. Radio tracking indicated that it would hit within a few kilometres of the aim point. Homer Newell and Edgar Cortright were observers in the VIP gallery of the Space Flight Operations Center. Walter Downhower, Chief of the Systems Design Section, gave a running commentary for the journalists in the auditorium. Since the spacecraft’s cruise attitude was compatible with imaging, Harris Schurmeier decided not to attempt the terminal manoeuvre lest this fail and ruin the mission. With 18 minutes to the predicted impact, the wide-angle cameras began their 5-minute warm­up, followed a few minutes later by the narrow-angle cameras. They were to switch over to full power at T-13 minutes and T-10 minutes respectively, and start to take pictures.

“Thirteen minutes to impact,’’ noted Downhower. “There is no indication of full power.’’ In due course, he followed up with, “Ten minutes to impact. We’re still awaiting transmission from the spacecraft of full-power video.’’

At this point Schurmeier told Goldstone to issue an emergency command to the spacecraft to switch on its TV system. This was done. Ranger 6 accepted the uplink and executed the command, but to no effect. When an audio representation of the downlink telemetry suddenly ceased at 09:24:32 GMT, Downhower observed, “We have our first report of impact. Still no indication of full-power video.’’ On striking the surface at a speed of 9,500 km/hour, the spacecraft vaporised. A movie camera had been mounted on a telescope in an effort to record any sign of the impact, but no flash or cloud of dust was evident.

A few hours later, Pickering set up an investigation headed by Donald Kindt, the JPL project engineer for the TV subsystem, and the next day Pickering appointed a group of section chiefs, chaired by Downhower, to monitor the investigation and to study its conclusions and recommendations. It was found that the failure occurred when the TV subsystem had briefly switched on during the ascent to orbit. Electrical arcing had destroyed the high-voltage power supply of the cameras and transmitters. The likely cause was shorting across the exposed pins of the umbilical connector of the Agena fairing which gave electrical access to the TV subsystem prior to launch. In the absence of a positive identification of the cause of the arcing, the investigation recommended (in part) that the subsystem be ‘locked out’ during the ascent to orbit, and enabled only after the spacecraft had separated from the Agena. On 11 February 1964 Pickering told Newell that Ranger 7 would have to be postponed, pending a definitive resolution of the issue.

Meanwhile, on 3 February Robert Seamans had established a NASA Board of Inquiry chaired by one of his deputies, Earl D. Hilburn. Concerned that JPL had not been able to positively identify the reason for the TV subsystem’s failure to transmit pictures, the Board reviewed the situation and on 14 February Hilburn alerted Hugh Dryden to the fact that his investigation had uncovered a number of deficiencies in the design and testing of the TV subsystem, pointing out in particular that the ‘split’ architecture was not entirely redundant. Hilburn judged JPL’s proposal to ‘lock out’ the TV subsystem during the ascent to be inadequate, and instead recommended that the system be completely redesigned – which would mean delaying the next mission by a year or more. Dryden was appalled at the prospect of such a long delay. Homer Newell feared that it would be decided simply to abandon the Ranger project. After considering the matter further, on 17 March Hilburn submitted his final report. This concluded that there must have been ‘‘two or more failures’’ in the TV subsystem; that the system was not as redundant as the designers had believed; and that testing had been inadequate – in particular, the report pointed out that the system had not been verified at full power during the pre-launch checks. In fact, JPL had decided early on in the project not to apply full power to ‘experiments’ in pre-launch checks lest a short circuit ignite the midcourse engine with a fuelled launch vehicle below. The recommendation was to redesign the TV subsystem. James Webb received the report, but took no immediate action.

On 23 March Harris Schurmeier, having seen Hilburn’s report, directed Maurice Piroumian of the Launch Vehicle Systems Section to further investigate the arcing issue. At liftoff, the plug of the ground equipment had withdrawn from the multi-pin connector and a flap had swung shut and latched to protect the connector. As this was the first flight of the TV subsystem and the connector was a new feature of the vehicle, it was possible that some aspect of its design was flawed. Tests were made over the next several months to try to determine how arcing might have taken place across these pins.

Alexander Bratenahl of the Space Sciences Division drew attention to the fact that the anomaly had coincided with the Atlas jettisoning its booster section. A study of long-range tracking camera footage showed that when this occurred the vehicle was briefly obscured by a large white cloud. On being informed by General Dynamics-

Astronautics that 180 kg of propellant drained out of the feed pipes when the lines were severed, Bratenahl speculated that suddenly dumping so much liquid into the rarefied air had produced a physical shockwave that was able to momentarily buckle the hinged flap inwards and mechanically short the pins; but an analysis showed that this was not feasible. At the end of June, Schurmeier terminated the investigation and classified the anomaly as a one-off.

Meanwhile, despite Hilburn’s report, it was decided to accept the Kindt team’s recommendation to ‘lock out’ the TV subsystem during the ascent; and on 11 May Schurmeier scheduled Ranger 7 for the window that would open on 27 July – as late as possible before priority would have to be assigned to the two Mariner missions to Mars scheduled for later in the year.

Bratenahl, however, continued to ponder the manner in which the Atlas staged. Intrigued when a more detailed analysis of the film showed flashes within the white cloud, he realised that the fluid dump had comprised both kerosene and oxygen, and that what he had naively presumed to be a simple physical shockwave was actually a detonation flash as the plume of the still-firing sustainer engine ignited the dumped propellants. The rapidly expanding spherical flashwave had washed over the vehicle, allowing plasma to penetrate the umbilical compartment to induce short circuiting. The timing was compelling: the Atlas shed its booster section at T + 140.008 seconds and the TV subsystem switched on at 140.498, coinciding with the progress of the flashwave up the length of the vehicle. On 30 July Bratenahl wrote a memo pointing out that arcing could be precluded if the cover flap were revised to form a hermetic seal. But by then Ranger 7 was in-flight to the Moon and the memo remained buried in an ‘in tray’ until after that mission.

In effect, NASA was learning by experience the many ways in which a spacecraft could be disabled. Although the chances of success increased as the failure modes were eliminated, the issue was whether Ranger would run out of spacecraft before it could deliver useful data!

GLOBAL MAPPING

In March 1967 the Surveyor/Orbiter Utilisation Committee agreed that since the first three Lunar Orbiter missions had achieved that project’s commitment in support of Apollo, the next should “perform a broad systematic photographic survey of lunar surface features in order to increase scientific knowledge of their nature, origin and processes, and to serve as a basis for selecting sites for more detailed scientific study by subsequent orbital and landing missions’’. This plan had been conceived at the Summer Study on Lunar Exploration and Science held in Falmouth, Massachusetts, between 19 and 31 July 1965, in the hope that the opportunity to undertake it would arise. The primary objective was to obtain contiguous coverage of at least 80 per cent of the near-side of the Moon at a resolution better than 100 metres. In fact, if the project’s priority had not been to reconnoitre specific areas in support of Apollo, the scientists would have started by mapping on a global basis.

To map in this way, the spacecraft would require to fly in a near-polar orbit with a perilune altitude fifty times greater than its predecessors, and as it would spend most of its time in sunlight the heat-rejection capacity of its protective base was enhanced by the installation of several hundred small quartz mirrors.

Lunar Orbiter 4 lifted off at 22:25:01 GMT on 4 May 1967. A midcourse burn of 60.8 m/s was required to deflect the trajectory away from the equatorial zone for a polar trajectory. This 53-second manoeuvre was made at 16:45 on 5 May. A further refinement was cancelled.

At 15:09 on 8 May the engine was reignited for 502 seconds to slow by 660 m/s and enter an orbit of 2,706 x 6,114 km with a period of 12 hours. The orbital plane was inclined at 85.5 degrees to the lunar equator, and oriented to enable the ground track to follow the migrating terminator to highlight topographic relief. The phase of the Moon was ‘new’ on 9 May; ‘first quarter’ would occur on 17 May and ‘full’ on 23 May. The photographic mission began at 15:46 on 11 May, while passing south to north on the eastern limb, and viewed Mare Australe and Mare Smythii. Given the

processor. It would also risk moisture in the hermetically sealed compartment condensing on the lenses. It soon became evident that the longer the exposed film spent in the loopers before being processed, the greater was the light pollution. Tests by Boeing indicated that it should be safe to repeatedly partially close and fully open the door. When this was done, the light leakage was reduced to an acceptable level. To overcome the loss of image contrast arising from dew on the lenses, the vehicle was briefly oriented at the start of each orbit to let the heat of the Sun clear the condensation. By the time that the difficulties were completely overcome, the plane of the orbit had migrated about 60 degrees in longitude. However, it proved possible to rephotograph much of this area again from apolune later in the mission.

On 20 May the drive mechanism of the film scanner began to misbehave. Clifford Nelson, the Project Manager at Langley, debated the irrevocable step of cutting the Bimat strip immediately versus continuing in the hope that all would be well. Jack McCauley argued for extending the contiguous coverage beyond the western limb to document the Orientale basin. Nelson agreed. When the scanner problem worsened on 25 May, it was decided to cut the Bimat. Although the photography had reached 100°W, the readout was at only 70°W and the challenge was to coax the remaining

processed exposures through the scanner in a manner which fooled the faulty logic unit. This task was successfully completed on 1 June.

The resolution of the mapping varied with altitude, but at perilune it was as fine as 60 metres, which was considerably better than was attainable from Earth. The results revealed hitherto unknown geological detail of the near-side polar and limb regions, and also increased to about 80 per cent the project’s coverage of the far-side. Frame M-187, taken from an altitude of 2,723 km, showed the Orientale basin in startling detail. Secondary exposures included westward-looking oblique pictures of Apollo sites. The micrometeoroid experiment had reported two hits. Manoeuvres on 5 and 8 June lowered the orbit to 77 x 3,943 km to approximate that intended for Lunar Orbiter 5 and to obtain selenodesy to assist in the planning of that mission. (Meanwhile, tracking of Lunar Orbiters 2 and 3 was showing that a low perilune would decay unless maintained by engine firings.) Contact with Lunar Orbiter 4 was lost on 17 July, and calculations indicated that its diminishing perilune would have caused it to crash at the end of October 1967. There was no ‘screening’ after this mission, as the images were for scientific research rather than Apollo landing site certification.