Category Paving the Way for Apollo 11

AS-205 lifted off from Pad 34 at 15:02:45 GMT on 11 October 1968 to fly the ‘C’ mission. Flown by Wally Schirra, Donn Eisele and Walt Cunningham, Apollo 7 was

to be open-ended up to 11 days and its purpose was to assess the performance of the Block II spacecraft.

The ascent phase was nominal and the S-IVB achieved a 123 x 152-nautical mile orbit. Prior to separating from the spent stage, the crew temporarily took command of the Instrument Unit and manually manoeuvred the combined vehicle in pitch, roll, and yaw, then they returned control to the launch vehicle. By the time the spacecraft separated at 002:55:02.40, venting of S-IVB propellants had raised the orbit to 123 x 170 nautical miles. The spacecraft moved clear, flipped and moved back in as if to retrieve the LM (which was absent). Since one of the four panels of the SLA had not fully deployed, it was decided that in future the panels would be jettisoned. One of the primary objectives was to demonstrate Apollo’s rendezvous capability using the spent stage as the target. At Schirra’s insistence, one man was awake at all times to monitor the spacecraft’s systems, even though the ongoing work made sleeping difficult. The rendezvous rehearsal was successfully achieved on the second day.

Although this was the first US spacecraft to have sufficient habitable volume for a man to leave his couch and move around, the crew suffered no disorientation in the weightless state, despite efforts to induce motion sickness. However, all three men developed head colds early on, making them grumpy, and in-flight TV, which was a secondary objective, provided a focus for their frustration. When the monochrome camera was finally switched on, however, it delivered excellent results and the crew played up to their audience. But it was a long and tedious flight of monitoring the systems to evaluate their performance, always prepared to intervene in the event of a problem. In fact, it was an exercise in would later be derided as “boring holes in the sky’’.

At 11:11:48 GMT on 22 October the command module splashed in the Atlantic 1.9 nautical miles from the target point. It initially assumed an apex-down attitude, but was soon turned apex-up by the inflatable bags on its nose. The astronauts were retrieved by helicopter and arrived on USS Essex an hour later.

The Apollo 7 mission was successful in every respect, with the service propulsion system firing perfectly eight times. Indeed, afterwards Schirra described the flight as a “101 per cent success’’. In combination with previous missions and ground tests, it certified the CSM for use in Earth orbit and for tests in the cislunar and lunar orbital environments.

On 7 November 1968 George Mueller declared that AS-503 was fit for a mission to the Moon. On 11 November Sam Phillips recommended to the Manned Space Flight Management Council that Apollo 8 enter lunar orbit. Later that day, Mueller told Thomas Paine that he had discussed the mission with the Science and Technology Advisory Committee and with the President’s Science Advisory Committee, both of which had endorsed the proposal, and he recommended that it should be undertaken. After speaking to Frank Borman by telephone, who confirmed his willingness to fly the mission, Paine gave the formal go ahead and told Phillips to make the necessary arrangements. The next day, NASA announced that Apollo 8 would be launched on 21 December and attempt a lunar orbital mission. Earlier in the year, Michael Collins had withdrawn from the crew to undergo a surgical procedure, and had been replaced by his backup, James Lovell.

Tom Stafford, John Young and Gene Cernan were announced on 13 November as the prime crew of Apollo 10, backed up by Gordon Cooper, Donn Eisele and Edgar Mitchell. This established the precedent for a crew backing up one mission, skipping two, and becoming the prime crew of the mission after that. It had yet to be decided, however, whether Apollo 10 would fly the ‘F’ or the ‘G’ mission.[51]

On 9 October 1968 AS-503, complete with CSM-103 and LTA-B, was rolled out to Pad 39A. The countdown demonstration test was completed on 11 December, and the actual countdown began at 00:00 GMT on 16 December. The launch window ran from 20 to 27 December, and it had been decided to try for 21 December to enable the astronauts to inspect the ALS-1 landing site in eastern Mare Tranquillitatis soon after local sunrise.

Frank Borman, James Lovell and Bill Anders entered the spacecraft with a little under 3 hours on the clock. There were no unplanned holds, and Apollo 8 lifted off at 12:51:00 GMT on 21 December for the ‘C-prime’ mission.

The ascent was nominal and the deviations from the trajectory when the S-IVB cut off at T+ 684.98 seconds were + 1.44 ft/sec in velocity and -0.01 nautical mile in altitude, which was almost perfect. At 002:27:22, after the S-IVB and spacecraft had been thoroughly checked, Collins, serving as the CapCom in Mission Control, made the momentous call, ‘‘Apollo 8, you are ‘Go’ for TLI.’’

The 317.7-second translunar injection was started at 002:50:37.8 and produced a velocity of 35,505.4 ft/sec. The spacecraft separated 30 minutes later and the four SLA panels were jettisoned. After turning around, the spacecraft’s ability at station­keeping with the spent stage was assessed. A 1.1-ft/sec manoeuvre was performed at 003:40:01 using the reaction control system of the service module to move clear of the stage, and a 7.7-ft/sec manoeuvre at 004:45:01 increased the separation rate.

At 004:55:56.0 the S-IVB opened its hydrogen vent valve and at 005:07:55.8 it passed oxygen through the engine. At 005:25:55.8 the auxiliary propulsion system was ignited and burned to depletion. The accumulated velocity increment placed the stage on course to fly by the trailing limb of the Moon at an altitude of 681 nautical miles and pass into solar orbit. The spacecraft’s service propulsion system executed a 2.4-second, 20.4-ft/sec midcourse manoeuvre at 010:59:59.2. A 24.8-ft/sec change had been planned, but the engine delivered less thrust than expected and a correction was made at 060:59:55.9 to refine the trajectory. These burns served to calibrate the service propulsion system in advance of calculating the orbit insertion manoeuvre.

In contrast to Apollo 7, this time all three crewmen experienced nausea as a result of rapid body movement, with the symptoms lasting up to 24 hours. The first of six TV transmissions started at 031:10:36 and ran for 23 minutes 37 seconds. The wide – angle lens gave an excellent view of the inside of the spacecraft, where Lovell was preparing a meal, but the telephoto lens passed too much light and pictures of Earth were poor. After a procedure was devised to tape a filter of the still camera onto the TV camera, it produced improved pictures of Earth during a transmission starting at 055:02:45. At 055:38:40 the astronauts were alerted that they had become the first people to enter a region where the gravitational attraction of another body exceeded that of Earth. The spacecraft had been slowing as it climbed up from Earth, but now it began to accelerate as it was drawn in by the Moon. However, they were not yet committed. If a reason developed not to brake into lunar orbit, then Apollo 8 would simply continue on its ‘free return’ trajectory around the back of the Moon and be ‘slingshot’ back to Earth. Although everything was going well, the translunar coast was frustrating in the sense that at no time were the crew able to see their objective owing to the spacecraft’s trajectory in relation to the positions of the Moon and the Sun.

The lunar orbit insertion manoeuvre began at 069:08:20.4 at an altitude of 75.6 nautical miles above the far-side of the Moon, and the 246.9-second burn produced an orbit ranging between 60.0 and 168.5 nautical miles with its high point above the near-side. After the post-burn checklist had been attended to, and while still passing over the far-side, the astronauts had their first opportunity to inspect the surface of the Moon up close. At 071:40:52 they gave a 12-minute TV transmission showing the passing terrain. In contrast to geologists, the astronauts described the surface in terms of ‘‘a battlefield’’, ‘‘a sandbox torn up by children’’, ‘‘a volleyball game played on a dirty beach’’, ‘‘plaster of Paris’’, or (vaguely scientifically) as ‘‘pumice’’. Bright ray craters appeared just as if they had been made by a ‘‘pickaxe striking concrete’’. The colour was varied, sometimes appearing to be black and white, yet other times displaying a distinctly brownish tan. In terms of mood, the surface was ‘‘desolate’’, ‘‘bleak’’ and ‘‘forbidding’’. A 9.6-second burn at 073:35:06.6 circularised the orbit at 60 nautical miles.

As this was the first opportunity for humans to directly observe the Moon at close range, James Sasser of the Apollo Spacecraft Project Office in Houston had served as the ‘project scientist’ for the mission. He formed an advisory team and this drew up a program of photography and visual observations for the crew to perform using a Maurer 16-mm movie camera and a Hasselblad with a 250-mm lens. In particular, the Manned Spacecraft Center wanted views of the eastern limb to assist in selecting landmarks for a lander’s navigational checks prior to the powered descent. Some of this documentation was to be overlapping vertical and oblique pictures which would enable stereoscopic analysis to determine the geographical position and elevation of each feature, but the movie camera was also to be fitted to the spacecraft’s sextant to depict the landmarks in context. In addition, some ‘scientific’ targets were marked on the flight charts as ‘targets of opportunity’ which were to be inspected if time and circumstances allowed. These were to provide either detailed coverage of specific features or broad coverage of areas which had not been adequately imaged by the Lunar Orbiters. And, of course, the ALS-1 landing site was to be inspected. Most of the scientific observing and photography was assigned to Anders, the LMP without a lunar module. Jack Schmitt, a professional geologist who was hired as an astronaut in 1965, served as the main interface between Sasser’s team and the Apollo 8 crew in training, but some briefings were provided by US Geological Survey staff. At the suggestion of Wilmot N. Hess, Director of the Science and Applications Directorate at the Manned Spacecraft Center, SasseTr’s team had set up a ‘science support’ room in Mission Control to listen to the astronauts’ commentaries and watch the TV of the lunar landscape passing below the spacecraft.

The astronauts could recognise surface features in shadows lit by Earthshine, and could see detail on sunward-facing slopes which had been ‘washed out’ in the Lunar Orbiter pictures. In fact, they could perceive detail to within 5 degrees of the ‘zero phase’ point, which is the line of sight with the Sun directly behind the observer. In planning the lunar landing the lower limit for Sun angle had been set at 6 degrees, but the astronauts could see surface detail at angles as low as 2 degrees. They were able to confirm that the upper limit of 16 degrees provided excellent definition, and their observations suggested that it might be possible to raise the limit to 20 degrees – but no higher than this. This enabled the lighting constraints for the lunar landing to be relaxed.

Of the two candidate landing sites in Mare Tranquillitatis, ALS-1 in the east was brighter; so much so, in fact, that it was debatable whether it was truly mare material or a flatfish portion of the adjacent terra. Observing it visually from an altitude of 60 nautical miles, Lovell said it reminded him of an aerial view of Pinacate in Mexico, a volcanic field which he had been shown in training.

Owing to crew fatigue, Frank Borman took the decision at 084:30 to cancel all secondary activities during the final two revolutions, to allow the crew to rest. The only tasks during this period were an alignment of the inertial guidance system and the preparations for transearth injection. But at 085:43:03 they provided the planned 27-minute TV transmission showing the Moon and Earth, and to mark the fact that it was Christmas Eve they recited the first ten verses of the Book of Genesis from the Bible prior to signing off with, ‘‘Good night, good luck, a Merry Christmas, and God bless all of you – all of you on the good Earth.’’

Radio tracking indicated that by the time Apollo 8 was ready to head for home the mascons had perturbed its initially circular orbit into one of 58.6 x 63.6 nautical miles. At 089:19:16.6, after ten revolutions of the Moon, the 203.7-second transearth injection was made on the far-side of the Moon at an altitude of 60.2 nautical miles, which was just about perfect. After returning to the Earth’s gravitational influence, the spacecraft progressively accelerated. Only one small midcourse correction was required. It was made at 104:00:00, and the 15.0-second burn by the service module reaction control system imparted a change of 4.8 ft/sec.

On shedding the service module, the command module adopted its entry attitude and at 146:46:12.8 hit the entry interface travelling at 36,221.1 ft/sec. It pursued an automatically guided profile. The ionisation bathed the interior of the cabin in a cold

An oblique view by Apollo 8 looking northwest across the eastern part of Mare Tranquillitatis. The crater in the foreground is Taruntius-F, and one of the Cauchy clefts crosses the upper part of the picture. The ALS-1 site is out of frame to the south.

blue light as bright as daylight. At 180,000 feet, as expected, the lift vector deflected the vehicle to 210,000 feet, then it resumed its downward course. It splashed into the Pacific 1.4 nautical miles from the target at 15:51:42 on 27 December. It adopted an apex-down position, but promptly righted itself. The astronauts were soon recovered and flown by helicopter to USS Yorktown.

This audacious mission, described as the “greatest voyage since Columbus”, took NASA a giant step towards achieving Kennedy’s challenge.

On 6 January 1969 Deke Slayton called Neil Armstrong, Michael Collins and Buzz Aldrin to his office at the Manned Spacecraft Center and told them that they would fly Apollo 11 and should assume their mission would involve a lunar landing.

On 10 January 1969 John Stevenson, Director of Mission Operations at the Office of Manned Space Flight, circulated a revised version of the tentative schedule for the year that was issued early in 1968. This called for launching the delayed ‘D’ mission on 28 February. As the ‘E’ mission had been rendered irrelevant by Apollo 8, this meant that if the ‘F’ mission flew in May and was satisfactory, it should be possible to attempt the lunar landing in July. The rationale for the ‘F’ mission was to obtain experience of operating in deep space, but after Apollo 8 the issue became whether another test in lunar orbit was required. The decision was postponed until LM-3 had been put through its paces.

Apollo 9 was to be the ‘D’ mission – a lunar module manned flight demonstration in Earth orbit. The payload for the AS-504 launch vehicle was CSM-104 and LM-3. As they were to operate independently, the spacecraft were given radio call-signs. The blue wrapping of the command module for its shipment to the Cape had given it the appearance of a sweet, so it was named ‘Gumdrop’. The arachnid-like configuration of the lunar module prompted the name ‘Spider’.

The launch was scheduled for 28 February 1969 and the countdown was begun at 03:00:00 GMT on 27 February with 28 hours on the clock, but 30 minutes into the planned 3-hour hold at T-16 hours the clock was recycled to T-42 hours in order to enable the crew of James McDivitt, David Scott and Rusty Schweickart to recover from a mild respiratory infection. The count picked up at 07:30:00 on 1 March and the vehicle lifted off from Pad 39A on time at 16:00:00 GMT on 3 March.

The ascent was nominal and at S-IVB cutoff at T+664.66 seconds the deviations were +2.86 ft/sec in velocity and -0.17 nautical mile in altitude, with the result that the initial orbit was almost perfect at 100 nautical miles. At 002:41:16.0 the S-IVB released the CSM, which moved clear, turned end over end to aim its apex at the top of the LM and moved back in. At 003:01:59.3 it docked at the first attempt, marking the first use of this apparatus. Once the tunnel between the two spacecraft had been pressurised, the crew opened the apex hatch of the command module to confirm that all the latches on the docking ring had engaged, and after lines had been connected to supply power to the dormant LM the hatch was reinstalled. On a command issued by the CSM at 004:08:09 the S-IVB released the docked combination.

After the spacecraft was clear, the S-IVB reignited its engine at 004:45:55.5 to raise an apogee of 1,672 nautical miles. Then, after a period of coasting to allow the engine to cool down, it initiated a final burn at 006:07:19.3 to achieve a velocity of 31,620 ft/sec which would send it into solar orbit.

Meanwhile, at 005:59:01.1 a 5.2-second burn by the service propulsion system raised the spacecraft’s orbit to 111 x 128 nautical miles. Three further manoeuvres on the second day in space measured the oscillatory response of the docked vehicles to obtain data designed to improve the autopilot’s response in this configuration, and also burned off the CSM’s propellant to increase the fidelity of manoeuvres which it would later perform in Earth orbit to rehearse what a mission would do in lunar orbit.

On the third day in space, Schweickart entered the LM to check out its systems. McDivitt joined him 50 minutes later. At about 045:52, shortly after the landing gear was deployed, McDivitt advised Mission Control that Schweickart had twice been sick – this illness would have an impact on the EVA planned for later in the mission. At 046:28 the astronauts made a 5-minute TV transmission from inside the LM. The descent engine was ignited at 049:41:34.5 for a 371.5-second burn in which the autopilot controlled the attitude of the docked vehicles and the astronauts manually throttled the engine to full thrust. The LM was deactivated at 051:00. Several hours later, a service propulsion system burn achieved an almost circular orbit of 125.9 x 131.0 nautical miles in preparation for the rendezvous sequence.

The EVA plan had called for Schweickart to exit the LM’s forward hatch, transfer to the command module hatch, and then return. But owing to his bouts of nausea the spacewalk was cut back from 2 hours 15 minutes to just 39 minutes, to be made on a single daylight pass. The LM was depressurised at 072:45, and the hatch opened at 072:46. Schweickart initiated his egress at 72:59:02, feet first and face up, and was completely out by 073:07. He was wearing the Extravehicular Mobility Unit suit and Portable Life Support System backpack which astronauts were to wear on the lunar surface. A 25-foot nylon safety tether precluded him drifting away. For stability, he inserted his feet into a pair of ‘golden slippers’ on the ‘porch’ of the descent stage. Meanwhile, at 073:02:00 Scott opened the side hatch of the command module and poked his head and shoulders out to monitor Schweickart. Although the transfer to the command module hatch had been cancelled, Schweickart was able to make an abbreviated study of translation and body-attitude-control using handrails affixed to the upper part of the LM. Before ingressing, Schweickart shot 16-mm movie footage of Scott’s activities, and 70-mm Hasselblad pictures of the exterior of both vehicles. Although the EVA was brief and did not involve a period of orbital darkness, it was sufficient to certify the suit and backpack for use on the lunar surface. The LM was repressurised at 073:53, and the CSM several minutes later. After a TV transmission from the LM that started at 074:58:03 and lasted 15 minutes, it was deactivated and McDivitt and Schweickart rejoined Scott.

On the fifth flight day McDivitt and Schweickart were back in the LM by 088:55 in order to prepare that ship for a period of free flight and an active rendezvous. At 092:22 the CSM oriented the pair into the attitude required for undocking. This was attempted at 092:38, but the latches did not fully release until 092:39:36. This was to be the first time that astronauts flew a spacecraft that was incapable of returning to Earth if an emergency were to arise – they relied on Scott to rescue them. Once free, the LM pirouetted while Scott made a visual inspection. At 093:02:54 the CSM used the thrusters of its reaction control system to make a separation manoeuvre. Over the next 6.3 hours, the LM undertook a series of manoeuvres which set up and executed a rendezvous. In the process, the descent propulsion system was fired under different control regimes and with the throttle being varied, after which the descent stage was jettisoned and the rendezvous was performed by the ascent stage. Terminal phase braking began at 098:30:03, and was followed by a period of station-keeping, then formation flying to facilitate mutual photography prior to docking at 099:02:26. McDivitt and Schweickart then transferred back to the CSM. The ascent stage was jettisoned at 101:22:45.0, and half an hour later ignited its main engine and fired it to depletion to enter a 126.6 x 3,760.9-nautical mile orbit.

The remainder of the mission was less hectic, being devoted mainly to conducting multispectral photography to prepare for the Skylab space station. At 169:30:00.4 the service propulsion system was fired in a 24.9-second burn which established the conditions for a nominal de-orbit. Unfavorable weather in the planned recovery area prompted a postponement of the de-orbit by one revolution, and it was performed at 240:31:14.8. The service module was jettisoned a few minutes later. The command module flew the entry profile under the control of its primary guidance system, and splashed into the Atlantic at 17:00:54 on 13 March about 2.7 nautical miles from the target. It settled in the ideal apex-up flotation attitude, and within an hour the crew were onboard USS Guadalcanal.

With Apollo 9 having successfully tested the LM in Earth orbit, the next issue was whether to fly the ‘F’ mission or to push on and attempt the lunar landing. In fact, it would be impossible for LM-4 to attempt the ‘G’ mission, as the software to conduct the powered descent was still under development. Furthermore, owing to propellant restrictions in the ascent stage of this somewhat overweight LM it would be unable to lift off and rendezvous. Tom Stafford, the Apollo 10 commander, argued against his crew waiting for LM-5 to become available. ‘‘There are too many ‘unknowns’ up there,’’ he noted. ‘‘We can’t get rid of the risk element for the men who will land on the Moon but we can minimise it; our job is to find out everything we can in order that only a small amount of ‘unknown’ is left.’’

On 24 March 1969 NASA stated that Apollo 10 would fly the ‘F’ mission. The original idea had called for the LM merely to undock, enter a slightly different orbit, rendezvous and redock, but in December 1968 the Mission Planning and Analysis Division at the Manned Spacecraft Center had urged putting the descent propulsion system through a high-fidelity rehearsal in which the LM would lower its perilune sufficiently to test the ability of the landing radar to detect and lock onto the surface. Howard Tindall also proposed that the LM should initiate the powered descent and then execute an early abort by ‘fire in the hole’ staging, but his colleagues convinced him that this would be too adventurous. One aspect of the decision to go ahead with the ‘F’ mission was to evaluate the tracking and communications of two vehicles in lunar orbit. In essence, it had been decided to exploit the fortuitous relaxation in schedule pressure and improve on Apollo 8 by performing a rehearsal to the point at which a later LM would initiate its powered descent.

The finally agreed plan called for the LM to separate from the CSM in the circular lunar parking orbit, enter an elliptical orbit having a perilune of about 50,000 feet located just east of the prime landing site, execute a low pass and then jettison the descent stage to make the rendezvous.

In April 1969 the site selectors met to decide the prime target for the first Apollo landing. The photographs of ALS-1 taken by Apollo 8 indicated the presence of a smooth blanket of light-toned material that softened or masked the landscape, and a study of the craters showed that the regolith was quite thick, which in turn implied a considerable age. The fact that the site was atypical of the maria made it unattractive for dating the maria, so it was rejected. This left ALS-2 in the southwestern part of Mare Tranquillitatis as the prime target. In early May, Jack Schmitt put it to Tom Stafford that the launch of Apollo 10 be slipped 24 hours from the proposed date so that the low-perilune pass over ALS-2 could be made in illumination matching that of a mission attempting to land there. This would enable high-resolution pictures to be taken of the site and the landmarks on the approach route. Stafford was receptive. Schmitt approached George Low, who asked Chris Kraft, who sought the advice of the flight control specialists – there were issues in favour and against. When the case was put to Sam Phillips he rescheduled the launch.

AS-505 had been installed on Pad 39B on 11 March, and Apollo 10 lifted off on schedule at 16:49:00 GMT on 18 May 1969 with Tom Stafford, John Young and Gene Cernan.

When the S-IVB cutoff at T + 703.76 seconds, the deviations were -0.23 ft/sec in velocity and -0.08 nautical miles in altitude. After translunar injection, CSM-106 ‘Charlie Brown’ separated, turned around and docked with LM-4 ‘Snoopy’, then the pair were released by the stage. The S-IVB then used propulsive venting to adopt a path that would fly past the Moon and enter solar orbit. At 026:32:56.8 the service propulsion system made a 49.2-ft/sec burn to match a July lunar landing trajectory. At 075:55:54.0 the spacecraft entered an initial lunar orbit of 60.2 x 170.0 nautical miles. Two revolutions later, this was refined to 59.2 x 61.0 nautical miles. During a 30-minute colour TV transmission the astronauts showed off the lunar surface. They reported the colour of the surface to be less grey than was described by Apollo 8. In particular, Mare Serenitatis appeared ‘‘tan’’, whereas Mare Tranquillitatis appeared ‘‘dark brown’’.

After undocking at 098:29:20, the vehicles took up station 30 feet apart while Young inspected the LM, and then the CSM moved off. A 27.4-second burn by the descent propulsion system at 099:46:01.6 placed the LM into a descent orbit with its perilune 15 degrees east of ALS-2. The landing radar was tested while passing over that site at an altitude of 47,400 feet an hour later. The pictures taken were of greater resolution than those transmitted by the Lunar Orbiters. Unfortunately, the 16-mm

This oblique view looking northwest across the crater Maskelyne was taken by the Apollo 10 Lunar Module ‘Snoopy’ as it flew low over Mare Tranquillitatis towards the ALS-2 target.

movie camera failed. A descent propulsion system burn at 100:58:25.9 put the LM into an orbit of 12.1 x 190.1 nautical miles to arrange a ‘lead angle’ equivalent to that which would occur at cutoff of an ascent from the lunar surface. At 102:44:49, during preparations to start the rendezvous with the CSM, the LM started to wallow off slowly in yaw and then stopped, and several seconds later it initiated a rapid roll accompanied by small pitch and yaw rates. Subsequent analysis revealed that this anomalous motion was due to human error. The control mode of the abort guidance system had inadvertently been returned to AUTO instead of the Attitude HOLD mode for staging. In AUTO, the abort guidance system steered the LM to enable the rendezvous radar to acquire the CSM, which at this point was not in accordance with the plan. The required attitude was re-established by the commander taking manual control. The descent stage was jettisoned at 102:45:16.9, and 10 minutes later an ascent propulsion system burn achieved an orbit of 11.0×46.5 nautical miles. This matched the insertion orbit for a mission returning from the surface. The LM had the active role in the rendezvous, and docked at 106:22:02. Two hours later the ascent stage was jettisoned, and during the next revolution the ascent propulsion system was fired to depletion in order to place the vehicle into solar orbit.

At 137:39:13.7, after 31 lunar revolutions, the CSM made the transearth injection. The aim was so accurate that it required only a 2.2-ft/sec refinement 3 hours prior to shedding the service module to centre the trajectory in the ‘corridor’ for atmospheric entry. The capsule splashed into the Pacific 1.3 nautical miles off target at 16:52:23 on 26 May and adopted the apex-up flotation attitude. The astronauts were aboard USS Princeton within the hour.

While Apollo 10 was in transit to the Moon, AS-506 was rolled out to Pad 39A in preparation for the Apollo 11 mission. After the pictures taken during the low pass over ALS-2 were examined, it was confirmed as the prime site for Apollo 11. ALS-3 in Sinus Medii was 2 day’s terminator travel westward and would be the backup. If the launch had to be delayed beyond the date for ALS-3, then the target would be ALS-5 in Oceanus Procellarum. In the post-flight debriefing, Tom Stafford pointed out that although the ALS-2 aim point was acceptable, the western end of the ellipse was much rougher. He advised Neil Armstrong that if he were to find himself at the far end of the ellipse and did not have the hover time to manoeuvre among the small craters and boulders to select a spot on which to land, then he would have to ‘‘shove off” – by which Stafford meant abort.

A week before Apollo 11 was due to launch, people began to congregate at the Cape communities of Titusville, Cocoa Beach, Satellite Beach and Melbourne. They came from all around the world in order to be able to tell their grandchildren they were present when men set off to try to land on the Moon. By 15 July hotels and motels allowed late-comers to install camp beds in lounges and lobbies, but most people spent the night on the beaches and by the roadside, generating the worst congestion

in Florida’s history. With the notable exception of alarm clocks, which rapidly sold out, shops were able to supply the hoards. As it was to be a dawn launch, the parties ran through the night.

When AS-506 lifted off at 09:32:00 local time on 16 July on a mission to accept President Kennedy’s challenge of landing a man on the Moon before the decade was out, it was estimated that there were about a million people present and 1,000 times as many watching on ‘live’ television.

No-one could be certain that the objective would be achieved, but the way had certainly been well paved.

[1] He did not infer from the absence of detail in the shadows that the Moon was airless, nor did he suggest the presence of open water.

[2] In fact, one of the few names introduced by van Langren to have survived is Langrenus, by which he honoured his own family.

[3] Selene was the Greek moon-goddess.

[4] Like Herschel and Schroter, von Gruithuisen believed the Moon to be inhabited, and after using a small telescope he reported in 1824 his discovery of a city in the equatorial zone near the meridian; but this was later shown to be merely a group of shallow ridges that were visible only when the Sun was low on the local horizon.

[5] For over half a century, geologists had argued about how the Coon Butte crater formed – and this was for a structure that was accessible to in-situ examination. Could there be any hope of resolving the issue of the lunar craters, which could only be peered at from afar!?

[6] On transfer to NASA, the Langley Aeronautical Laboratory became the Langley Research Center, the Ames Aeronautical Laboratory became the Ames Research Center, the Lewis Flight Propulsion Laboratory became the Lewis Research Center and the High-Speed Flight Station became the Flight Research Center.

[7] On 3 December 1958 Eisenhower ordered that JPL be transferred to NASA. This took effect on 1 January 1959, although only under contract, since the facility was owned by Caltech, which NASA paid. In September 1959 the Pentagon voluntarily yielded the Army Ballistic Missile Agency since the military had decided it did not require the Saturn launch vehicle; it would develop the Titan III instead. On 21 October 1959 NASA announced that it was to gain von Braun’s rocket team. On 1 July 1960 the Army Ballistic Missile Agency became the Marshall Space Flight Center.

[8] Physicists James van Allen, Homer Newell, Charles Sonett and Lloyd Berkner were notable early members of the ‘sky science’ community.

[9] Colloquia were held quarterly at different venues on the West Coast through to May 1963.

[10] As would later be realised, Mare Moscoviense fills the floor of a 300-km-diameter crater and Tsiolkovsky covers a portion of the floor of a crater which has a prominent central peak.

[11] The name Ranger set a trend for lunar projects with the names Surveyor and Prospector; in contrast to Mariner for planetary missions – that is ‘land’ names as against ‘sea’ names.

[12] Later, launch operations would be made a separate field centre.

[13] In early 1962 the entire NASA launch organisation was restructured.

[14] The Soviet spacecraft fell silent on 27 February 1961, at a distance of 2З million km from Earth. A launch on 4 February had stranded a similar spacecraft in parking orbit, but its role was disguised by naming it Sputnik 7.

[15] Surface science was only one of the objectives; there were the investigations to be made during the terminal approach, and achieving these would mark an acceptable compromise on the first mission.

[16] They were Lieutenant Commander Alan Bartlett Shepard Jr, Lieutenant Malcolm Scott Carpenter and Lieutenant Commander Walter Marty Schirra Jr from the Navy; Lieutenant Colonel John Herschel Glenn Jr from the Marines; and Captain Virgil Ivan ‘Gus’ Grissom, Captain Donald Kent ‘Deke’ Slayton and Captain Leroy Gordon Cooper Jr from the Air Force.

[17] This reasoning would resurface when John F. Kennedy asked for a worthy challenge.

[18] In a reorganisation on 8 December 1959, the Office of Space Flight Development had become the Office of Space Flight Programs.

[19] In fact, NASA could have launched Shepard several weeks ahead of Gagarin’s flight. If this had been done, Kennedy may well not have issued the challenge of landing a man on the Moon before the decade was out. The fact that Shepard’s flight had been only suborbital whereas Gagarin’s was orbital, would probably not have mattered, since the world’s first ‘spaceman’ would have been an American. The fact that America ‘lost’ both the first satellite and the first man into space could be said to be directly responsible for the race to the Moon. It serves to illustrate that history is not an irresistible tide, it can be extremely sensitive to the outcome of singular events.

[20] Earth imparts a gravitational acceleration of 32.2 ft/sec2.

[21] Newell also wished to maximise the amount of science on manned flights in Earth orbit.

[22] Despite Gold’s assertion that the dust would react only slowly upon being loaded, reporters would remain fascinated by the possibility that a lander would rapidly become submerged by it!

[23] The crater made by Ranger 8 was photographed by Lunar Orbiter 2, and found to be about 13.5 metres in diameter with a mound at its centre.

[24] The converter was installed at JPL, not at Goldstone.

[25] The crater made by Ranger 9 was photographed by Apollo 16 in 1972. At 14 metres in diameter, it was similar to that of its predecessor.

[26] The delay in the Centaur stage was in part due to problems with the configuration of its propellant tanks, but also because the Marshall Space Flight Center was busy with the Saturn launch vehicles. In early 1962, therefore, the Centaur had been transferred to the Lewis Research Center.

[27] In the case of Lunar Orbiter, the wide-angle images would be referred to as medium (M) frames and the narrow-angle images as high-resolution (H) frames.

[28] In fact, Bimat was similar to the Polaroid process.

[29] In particularly, the Planetology Subcommittee called for the Lunar Orbiter Block II to undertake selenodesy, gamma-ray, X-ray, magnetometry, microwave and non-imaging radar studies from orbit.

[30] This was because on a direct ascent the translunar injection point was necessarily near the latitude of the launch site, and for a launch from Florida this was north of the equatorial plane on a southerly heading, which meant that by the time the spacecraft reached lunar distance it would be south of the equatorial plane.

[31] The Manned Space Flight Network was operated under the direction of the Goddard Space Flight Center in support of the Manned Spacecraft Center.

[32] In fact, stereoscopic analysis of the Lunar Orbiter pictures proved difficult due to the manner in which they were scanned in narrow strips for transmission, as this gave the impression of the surface as being corrugated.

[33] Whereas in summer the Moon reaches its ‘full’ phase south of the equator, in winter it does so north of the equator, and since for the early Surveyors the landing sites were well to the west of the lunar meridian with arrival soon after local sunrise in winter months the translunar injection had to be made from south of the Earth’s equator. The restartable Centaur facilitated this by using its first burn to achieve a parking orbit and, once south of the equator, using its second burn to head for the Moon.

[34] During a solar eclipse, when the Moon occults the Sun to terrestrial observers, the irregular profile of the lunar limb often allows light from small sections of the solar disk to be viewed during totality, giving rise to a phenomenon known as Baily’s Beads after the British astronomer Francis Baily who first noted them during an annular eclipse on 15 May 1836.

[35] The term ‘psia’ means pounds of force per square inch on an ‘absolute’ scale measured relative to zero. If a pressure gauge is calibrated to read zero in space, then at sea level on Earth it would read 14.7 psi, which is sea-level atmospheric pressure. A value specified in psia is therefore relative to vacuum, rather than a differential relative to the pressure at sea level on Earth. For large numbers, the difference is insignificant.

[36] The pictures taken by Lunar Orbiter 1 showing Earth against the lunar limb were in black – and-white.

[37] Both Apollo 15 and Apollo 17 were sent to sites imaged by Lunar Orbiter 5; although in the case of Apollo 17 the observations by Apollo 15 also contributed to the selection.

[38] In the late 1950s J. J. Gilvarry argued that the maria were once water oceans, and hosted life. He said the now-dry plains were sedimentary rock, and dark owing to the presence of organic material. He claimed the elemental abundance data from the alpha-scattering instrument matched mudstone even better than it did basalt.

[39] Although NASA was unaware of it, a gamma-ray spectrometer operated in lunar orbit by Luna 10 in 1966 had provided a rudimentary analysis of the composition of the lunar surface across a wide range of latitudes, and the results showed there to be no significant exposures of acidic rock in the highlands.

[40] The term ‘facies’ was introduced to geology in 1838 by the Swiss stratigrapher Amanz Gressly to specify a body of rock having given characteristics.

[41] They were: Lieutenant Charles ‘Pete’ Conrad Jr, Lieutenant Commander James Arthur Lovell Jr, and Lieutenant Commander John Watts Young from the Navy; Major Frank Frederick Borman II, Captain James Alton McDivitt, Captain Thomas Patten Stafford, and Captain Edward Higgins White II from the Air Force; Neil Alden Armstrong, a former naval aviator, now a civilian test pilot for NASA; and Elliot McKay See Jr, a civilian test pilot for the General Electric Company.

[42] Slayton had been grounded in 1962 owing to a heart irregularity while training for a Mercury mission.

[43] They were: Major Edwin Eugene ‘Buzz’ Aldrin Jr, Captain William Alison Anders, Captain Charles Arthur Bassett II, Captain Michael Collins, Captain Donn Fulton Eisele, Captain Theodore Cordy Freeman, and Captain David Randolph Scott from the Air Force; Lieutenant Alan LaVern Bean, Lieutenant Eugene Andrew Cernan, Lieutenant Roger Bruce Chaffee, and Lieutenant Commander Richard Francis Gordon Jr from the Navy; Captain Clifton Curtis Williams from the Marines; Ronnie Walter Cunningham, a research scientists at the RAND Corporation; and Russell Louis ‘Rusty’ Schweickart, a research scientist at the Massachusetts Institute of Technology.

[44] This name change officially took effect on 20 December 1963.

[45] On 26 October 1962 a nomenclature was introduced by which the pad abort tests were to run in sequence from PA-1; the Little Joe II flights were to start at A-001; missions using the Saturn I were to start at A-101; missions using the Saturn IB were to start at A-201; and missions using the Saturn V were to start at A-501, with the ‘A’ standing for ‘Apollo’. The ‘SA’ prefix was employed by the Marshall Space Flight Center (giving precedence to the launch vehicle) and the ‘AS’ prefix was used by the Manned Spacecraft Center (giving precedence to the spacecraft). In addition, the term ‘space vehicle’ was introduced to describe the integrated ‘launch vehicle’ and ‘spacecraft’, with the latter comprising the CSM, the LM (if present) and the SLA structure.

[46] NASA’s Flight Research Center at Edwards Air Force Base was renamed in Dryden’s honour.

[47] On 30 March 1967 George Low suggested that the AS-201 and AS-202 test flights be assigned the designations Apollo 2 and Apollo 3 retrospectively in order to fill in the gap, but this was rejected by Mueller on 24 April. AS-203 was not included because it did not carry a spacecraft.

[48] The last two categories represented the lunar part of the Apollo Applications Program which was being promoted by George Mueller, and when this fell by the wayside the reconnaissance surveys were deleted and the main program was expanded to include ‘enhanced capability’ landings.

[49] Times in this hhh:mm:ss format are with reference to the time of launch.

[50] It is worth noting that the guidance system in the IU performed this magnificent recovery entirely on its own.

[51] CSM-101 had flown on Apollo 7, CSM-102 had been retained by North American Aviation for ground testing, CSM-103 had been assigned to the Apollo 8 ‘C-prime’ mission, CSM-104 was to fly the Apollo 9 ‘D’ mission, CSM-105 was for ground testing, and CSM-106, which was delivered to the Cape on 25 November 1968, was assigned to Apollo 10.

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.

The first International Polar Year was held between 1882 and 1883 to coordinate meteorological, magnetic and auroral studies. The eruption of Krakatoa in

Indonesia on 20 May 1883 had a temporary but significant effect on the atmosphere. A second International Polar Year was held 50 years later. In 1950 the International Council of Scientific Unions proposed to exploit the technologies developed in the years since the Second World War to undertake geophysical research on a global basis to study the solar-terrestrial relationship. In early 1952 it was agreed that this International Geophysical Year would run from July 1957 to December 1958, a period which was expected to coincide with the time of maximum solar activity in the 11-year cycle of sunspots. In early 1954 the National Security Council said the US “should make a major effort during the International Geophysical Year”, and directed the Pentagon to provide “whatever support was necessary to place scientists and their instruments in remote locations” to make observations.

In August 1953 physicist Fred Singer outlined to the International Congress of Astronautics a 45-kg satellite for MOUSE (Minimum Orbital Unmanned Scientific Experiment). He spent the next year promoting it. In October 1954 he canvassed the US delegation to the meeting in Rome, Italy, of the International Geophysical Year’s Steering Committee, and as a result a resolution was passed which encouraged participants to investigate the possibility of launching a satellite as the highlight of the program.

In November 1954 Charles Wilson told journalists he did not care if the Soviets were first to put up a satellite. Despite the National Security Council directive for “a major effort’’ in support of the International Geophysical Year, it was not until 1955 that Wilson endorsed a satellite. In July 1955 Eisenhower announced that the US would put up a satellite for the International Geophysical Year. Eisenhower saw it as a one-off scientific venture. He assigned to the Pentagon the decision for how it should be achieved. There was intense rivalry between the services, because such a spectacle would boost that service’s claim to be assigned a greater responsibility for long-range missiles. Shortly before Eisenhower’s announcement, Donald Quarles, Chief of Research and Development at the Pentagon, had set up a committee chaired by Homer Joe Stewart, a physicist at the University of California at Los Angeles, to review the capabilities of the services. The National Security Council had stipulated that the satellite must not impede the development of the Atlas missile, which was only now beginning to gear up as a ‘crash’ national program. This ruled out the Air Force.

The Army proposed Project Orbiter, claiming that if the Redstone missile, which was an improved V-2, were to be fitted with three upper stages, a satellite would be able to be launched by January 1957, which was before the start of the International Geophysical Year. The Navy had Project Vanguard, in which an improved form of the Viking ‘sounding’ rocket introduced in 1949 for stratospheric research would be augmented with two upper stages. Part of the rationale for the Stewart Committee selecting Vanguard was the perceived greater reliability of requiring only two upper stages, instead of three. In addition, the Committee was impressed by the in-line configuration of the Vanguard stages, as opposed to clustering small solid rockets to form the upper stages of the Redstone launch vehicle. Nevertheless, Stewart himself had supported the Army’s proposal. One factor was that whereas the Redstone was a weapon and was classified, the Viking was not classified. Another rationale, added later, was that it would be better to use a ‘civilian’ rocket for this scientific project. The Committee was not concerned that Vanguard would not deliver as early as the Army claimed for Orbiter – it was simply presumed that the first satellite would be American, and provided that it was launched within the period of the International Geophysical Year it would serve its purpose. On 9 September 1955 the Pentagon endorsed the Committee’s recommendation. The spherical Vanguard satellite would weigh about 1.5 kg, and would transmit a radio signal that would allow the study of electrons in the ionosphere and thus make a unique contribution to the International Geophysical Year.

Since the services were only loosely controlled by the Department of Defense, the Army set out to contest the decision, emphasising that the Redstone could launch a satellite without impeding military work. When on the Stewart Committee, Clifford C. Furnas of Buffalo University had sided with the Army. Now at the Pentagon, he advised the Army to have its missile ready as a backup in case Vanguard faltered.

On 1 February 1956 the Army Ballistic Missile Agency was established at the Redstone Arsenal, Major General John B. Medaris commanding. It was to develop an intermediate-range ballistic missile named Jupiter. As the warhead would enter the atmosphere at a faster speed and be subjected to greater heating than that of the short-range Redstone, it was decided to test the new re-entry vehicle by firing it on a ‘stretched’ Redstone equipped with two upper stages made by clustering small solid rockets. The fact that this ‘Jupiter-C’ would enable the Army to develop and test a vehicle capable of launching a satellite was, of course, entirely coincidental! When the first test flight on 20 September 1956 reached a peak altitude of 1,000 km and flew 4,800 km down the Air Force’s Eastern Test Range from Cape Canaveral, the Pentagon directed Medaris to personally guarantee that Wernher von Braun did not inadvertently place anything into orbit! One criticism of Vanguard was that although its first stage was based on the Viking, the project really involved developing a new integrated vehicle in a period of only 2 years. With Vanguard running late, Medaris sought permission to launch a satellite, but the Secretary of the Army refused – in fact, the Army Ballistic Missile Agency was ordered to destroy the remaining solid rockets obtained for the upper stages. In response, Medaris decided to leave them in storage to ‘assess’ their shelf life!

In public, Eisenhower maintained that launching a satellite was a one-off venture for the International Geophysical Year. In fact, this was a cunning ruse, because the aim was to use Vanguard to set the precedent of a US satellite passing over foreign territory, and thus preclude a legal challenge when the US began to send up satellites for military functions such as reconnaissance.

Soon after the US announced that it would launch a satellite for the International Geophysical Year, the Soviet Union said it intended to do the same. In mid-1957 the Soviet magazine Radio told its readers how to go about ‘listening’ to this satellite. In late August the TASS news agency announced the successful test flight of a ‘‘super long range’’ missile which was capable of striking ‘‘any part of the world’’. When a Soviet delegate at an International Geophysical Year meeting in Washington in late September was asked whether the promised satellite was imminent, he replied: ‘‘We won’t cackle until we’ve laid our egg.’’ In other words, wait and see!

On 4 October the 84-kg Sputnik was placed into an orbit which ranged in altitude between 220 and 950 km and transmitted its incessant ‘beep, beep, beep’ signal.

The news caused a world-wide sensation, but Eisenhower was not concerned. At a press conference on 9 October he dismissed Sputnik as a ‘‘small ball in the air’’ that ‘‘does not raise my apprehensions, not one iota’’. On the other hand, the mass of the satellite showed the capability of the Soviet intercontinental-range ballistic missile, and Eisenhower ordered an end to the administrative difficulties that were impeding funding for the American missile programs.

Lyndon Baines Johnson was not only the senior Democratic senator for Texas, as the Democratic leader in the Senate he essentially controlled majority congressional support for the legislative program: put simply, without his backing, the Republican administration was ineffective. Johnson saw Sputnik in terms of national security – the satellite could well have been an orbital bomb, waiting to be instructed to fall on an American city. He ordered a Congressional investigation into the state of national security preparedness. As a result, the public became aware that there was a ‘‘missile gap’’; and, almost overnight, ‘space’ was transformed from a fantasy into something that the US should be leading, since otherwise national prestige would be damaged.1

After the launch on 3 November of a heavier Sputnik with a canine passenger, Eisenhower demanded an increase in the pace of Vanguard, which was in trouble, and also authorised the Army Ballistic Missile Agency to prepare a Jupiter-C in case Vanguard should fail. Medaris had the solid rockets for the upper stages retrieved from storage and let von Braun loose.

On 6 December 1957 Vanguard ignited, lifted a few centimetres off the pad, then collapsed back and exploded in a fireball. On 31 January 1958 the Army launched a satellite using essentially the same vehicle configuration as the Stewart Committee had rejected. On being asked for permission to inform Washington of the success, Medaris reputedly said: ‘‘Not yet, let them sweat a little.’’ The satellite, Explorer 1, was integrated into the solid rocket of the final stage and inserted into an orbit which ranged between 360 and 2,550 km. The Geiger-Mueller tube it carried was supplied by James van Allen, a physicist at the University of Iowa, and detected the presence of charged-particle radiation trapped within the Earth’s magnetic field, far above the atmosphere.

With the development of nuclear-armed intercontinental-range ballistic missiles threatening to make manned strategic bombers obsolete, the Air Force reacted to the prospect of its strike force becoming ‘silo rats’ by claiming that it needed to develop a manned space flight capability. Its Ballistic Missile Division, headed by General Bernard Schriever, devised Man In Space Soonest. This envisaged a progression of steps that would result in an Air Force officer landing on the Moon in 1965. When this was submitted to the Pentagon in March 1958 the response was lukewarm – in

part owing to the estimated cost of $1.5 billion, but also due to the absence of a clear military necessity. In fact, the proposal was an example of what would be referred to in today’s parlance as a demonstration of ‘the vision thing’.

No sooner had the Army developed its Jupiter intermediate-range ballistic missile than the Pentagon assigned operational control of all land-based missiles with ranges exceeding 320 km to the Air Force, thus limiting the Army to ‘battlefield’ missiles. In fact, the Air Force had no use for the Jupiter, since it had just developed its own Thor intermediate-range ballistic missile.

The only prospect for the Army Ballistic Missile Agency was therefore to develop powerful launch vehicles for satellites. On 19 December 1957 the Army proposed the National Integrated Missile and Space Vehicle Development Program. Like the Air Force, the Army saw itself as the obvious service to explore space. In 1959 it proposed Project Horizon to achieve a manned lunar landing in 1965, but this was received no more enthusiastically than the rival Man In Space Soonest.

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.