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.

As William Herschel was passing sunlight through a prism in 1800, he found that heat was refracted just beyond the red end of the visible spectrum, so he named this infrared radiation. The Estonian physicist Thomas Johann Seebeck discovered in 1821 that if two wires of different metal are made into a loop by soldering their ends together, then an electric current will flow if the joins are at different temperatures. In 1856 Charles Piazzi Smyth utilised such a thermocouple to detect solar infrared reflecting off the Moon. Laurence Parsons inherited the 72-inch reflecting telescope built by his father at Birr Castle in Ireland. ft was the largest telescope in the world at that time. The common view was that since the airless lunar surface was exposed to the intense cold of space, it simply must be covered by ice. fn fact, S. Ericsson of Norway had proposed in 1869 that the lunar landscape was shaped by glaciation. fn 1870 Parsons equipped his telescope with a thermocouple and found that at lunar noon the temperature of the equatorial zone – where the Sun would pass close to the zenith – exceeded that of the boiling point of water, which indicated that the surface could not be ice. Measurements of the angle of polarisation of the surface published by M. Landerum in 1890 confirmed that it could not be ice. Despite the measured high temperatures at lunar noon, P. J.H. Fauth in Germany endorsed the idea that the landscape was shaped by glaciation, and in 1913 he and Hans Horbiger announced the highly unorthodox theory that ice was the essence of the cosmos! However, the vapour pressure of ice would cause it to sublime in the vacuum. ff ice were indeed present, it would have to be subterranean. fn 1916 Pierre Puiseux in Paris pointed out that if ice were present in the amounts claimed by Fauth, then it should be most evident at high latitudes where the Sun did not rise far above the horizon – yet there were no polar caps. Nevertheless, W. H. Pickering speculated that there might be ice at the summits of lunar peaks. The outcome of these studies was therefore that the majority of the surface was not ice.

fn 1930 Edison Pettit and Seth B. Nicholson put a thermocouple on the 100-inch reflector on Mount Wilson, which at that time was the largest telescope in the world, and discovered that the surface temperature in the equatorial zone varied by several hundred degrees during the monthly cycle. At the onset of a lunar eclipse in 1939 they measured the temperature plunge by 120°C in the space of an hour as the Moon entered the Earth’s shadow. This implied that the material on the surface was poor at retaining heat. On making more sophisticated measurements, they found that at the equator the temperature was +101°C at noon, fell to -39°C at sunset and -160°C at midnight. fn 1948 A. J. Wesselink in Holland inferred from these cooling rates that the Moon could not be exposed solid rock but must be covered by a blanket of loose material.

After the Second World War, the Moon was investigated at radio wavelengths. fn 1946 Robert H. Dicke and Robert Beringer in America detected thermal emission from the Moon at a microwave wavelength of 1.25 cm. Using the same wavelength, in 1949 J. H. Piddington and H. C. Minnett in Australia measured the temperature of the whole disk at a variety of phases over three lunations. The variation proved to be less extreme than it was at infrared wavelengths. The fact that the radio temperature lagged behind the optical phase of the Moon by 3.5 days suggested the presence of a thin insulating layer with low thermal conductivity. fn 1950 John Conrad Jaeger in Australia matched materials to the microwave observations made by Piddington and Minnett. Agreeing with Wesselink’s inference of loose material, Jaeger argued for a layer of ‘dust’, typically only several millimetres thick, resting on top of a granular material. Observations of lunar eclipses on 29 January 1953 and 18 January 1954 at microwave wavelengths by the US Naval Research Laboratory implied that only the uppermost part of the surface underwent a large variation in temperature. This was consistent with a thin layer of dust on a loose granular material. In 1962 J. F. Denisse in France announced that for wavelengths exceeding 30 cm there was no variation in temperature over the monthly cycle.

Taken together, these investigations indicated that whereas an optical telescope fitted with a thermocouple measured the temperature of the surface itself, the radio temperatures were averages for granular material to depths corresponding to several times the wavelength. The constancy at wavelengths greater than 30 cm implied that the material in the uppermost metre or so was such a poor conductor of heat that even when the Sun was at the zenith its heat did not penetrate that far. And at night, although the surface rapidly radiated away the heat it had gained during the day, the poor conductivity of the deeper material served to insulate it. The temperature at a depth of about one metre was estimated to be a constant -40°C. Candidates for the uppermost metre of material were a porous volcanic rock like pumice or a granular conglomerate. A colloquium held in Dallas, Texas, in 1959 concluded that the fine dust that formed the actual surface was probably of meteoritic origin. It was initially believed that the Moon is particularly bright at its ‘full’ phase due to there being no shadows in view – the objects at the centre of the disk cast no shadows, and objects away from the centre mask their shadows to terrestrial observers. But the absence of appreciable darkening of the limb proved to be a result of the fact that the surface ‘scatters’ more light back towards its source than it does in other directions. It was inferred from this that the material at the surface was a porous vacuum-sintered dust, and that sunlight which penetrated a ‘cavity’ was not absorbed but reflected back out towards its source.

In 1955 Thomas Gold, an astronomer with a wide-ranging interest who was then at the Royal Greenwich Observatory in England, proposed that particles of dust on the lunar surface would become electrically charged by the harsh ionising ultraviolet radiation from the Sun, and that in making the grains of dust repel each other this would cause them to flow remorselessly ‘down hill’ and collect in low-lying areas. Tests using powdered cement in a vacuum had shown that this tended to form fragile ‘fairy castle’ structures full of voids, which was consistent with the inference that the surface material was porous. Gold claimed that the maria were accumulations of dust, possibly several kilometres thick, and were of low albedo because the dust had been darkened through exposure to radiation. But whilst dust moving down hill could bury craters in low-lying terrain, it could not explain the missing ‘seaward’ wall of a crater such as Le Monnier on the margin of Mare Serenitatis, nor the dark floors of Archimedes sitting on elevated terrain or Plato embedded in the lunar Alps.

A. Deutsch in Leningrad suggested in 1961 that there might be life in the granular material where the temperature was constant, and that it lived off gases leaking from the interior. Expanding on this, Carl Sagan in America speculated that if the granular material were tens of metres deep, then it might contain a considerable amount of ice and organic material.

As the space age dawned, therefore, there were already interesting insights and speculations into the nature of the lunar surface material.

When on 25 May 1961 President Kennedy challenged his nation to land a man on the Moon before the decade was out, the sky scientists were unimpressed but the geologists were delighted.

On 8 June Hugh Dryden advised the Senate Committee on Aeronautics and Space Sciences that NASA intended to make use of automated spacecraft to strengthen the manned lunar program. In particular, it was essential to find out whether the surface would support the weight of the Apollo lander. As Dryden put it, ‘‘We want to know something about the character of the surface on which the landing is to be made, and obtain as much information as we can before man actually gets there.’’ Following up, Abe Silverstein provided some details. For a start, Ranger would be extended by four Block III missions. Congress authorised the funding for these missions several weeks later.

Clifford Cummings, JPL’s Lunar Program Director, visited NASA on 21 June and told Edgar Cortright and Oran Nicks, the two managers in Silverstein’s office who were responsible for Ranger, that the greatest single contribution this project could make to Apollo would be to provide high-resolution imagery to enable the nature of the lunar surface to be characterised to provide the information needed to design the landing gear of the Apollo lander. For this, the Block III would replace the surface package subassembly with a TV system that was more sophisticated than that made for the Block II. In the interim, some insight would be provided by the Block II radar altimeter and the accelerometers of the surface capsule as this impacted and rolled to a halt.

JPL recommended that the contract to develop the high-resolution TV system go to the same company that supplied the camera for the Block II, and this was agreed.

On 5 July 1961 JPL discussed the design of the system with the Radio Corporation of America, and it was decided to use a shutter (which was not a standard feature on a continuous-scan TV system) to define a ‘frame’ on a vidicon tube. The contract was signed on 25 August. Responsibility for the design, fabrication and testing of the system was delegated to the company. Harris Schurmeier’s Systems Division would monitor the work. On 31 August, Cummings appointed Allen E. Wolfe as the Ranger Spacecraft Systems Manager to assist James Burke with the increased work. Wolfe had replaced Gordon Kautz as Project Engineer in the Systems Division when Kautz was made Burke’s deputy. Wolfe’s first responsibility would be to steer the remaining Block II spacecraft through all phases of assembly and testing, and then supervise the development of the Block III.

The design of the high-resolution TV subsystem was finished in September 1961. It had three major assemblies: a tower superstructure incorporating a thermal shield to stand on the top of the hexagonal bus; a central box to house the main electronics; and, above, a battery of six cameras and their individual electronic systems. It used two types of camera. The ‘A’ type had a lens with an aperture ratio of f/1 and a focal length of 25 mm. The ‘B’ type had an f/2 lens with a focal length of 75 mm. There were two ‘A’ cameras and four ‘B’ cameras. The vidicons were all the same, but the entire 11-mm square image would be used for the full (F) frame and only the central 3-mm square for the partial (P) frame. One ‘A’ and one ‘B’ camera would operate a 5.12-second cycle in which the shutter fired to expose its vidicon and this was read out over an interval of 2.56 seconds, then erased over the next 2.56 seconds. They were to operate out of phase so that a frame was taken every 2.56 seconds. The other cameras would require 0.2 second to fire the shutter and perform the readout, and 0.6 second to erase. The faster cycle time for these cameras was because a smaller

area was to be scanned. They were to be cycled to take a frame every 0.2 second, in the hope that one camera would be able to provide a close-up picture just prior to impact. The cameras were mounted at angles designed to provide overlap to enable the relationship of one frame to be related to those preceding and following. The TV subsystem would have its own battery, independent of the bus, and a pair of 60-watt transmitters. Unlike the Block II, whose flow of pictures would conclude when the separation of the surface package caused the high-gain antenna to lose its lock on Earth, the Block III would continue to send pictures until it hit the surface. In all, the high-resolution TV subsystem would be 160 kg.6

As in the case of the Block I, the low-gain antenna would be in a fixed position at the top of the tower. The designers of the Block III had the luxury of being able to exploit the full payload capacity of the Atlas-Agena B, and this allowed some degree of redundancy in the basic systems.

On 19 September 1961 NASA announced that the Block IIIs were to be launched in January, April, May and August 1963 – certainly they were to be over before the first soft-landing Surveyor, which was expected in 1964.

On 25 June 1963 Floyd Thompson went to Washington to define the terms of the request for proposals. In particular, he did not wish it to be stated that the spacecraft should be spin stabilised; he wished to see what the bidders proposed. It was agreed to say only that the primary requirement was photographic data at medium and high resolution in order to facilitate the selection of sites for Surveyor and Apollo landers. The secondary objectives were to provide information on the size and shape of the Moon and the properties of its gravitational field. Information would also be sought on conditions near the Moon, including the micrometeoroid flux and total exposure to energetic particles and gamma rays – the latter having been shown by Ranger 3 to exist. A key requirement of the photographic system was that it identify the altitude of the orbiter at the time of an exposure, the orientation of the line of sight (relative to lunar north) and the angle of the Sun to the surface. In particular, it was desired to be able to determine the location of any surface feature to an accuracy of 1 km.

On 23 August Lee Scherer presented the request for proposals to Oran Nicks and Edgar Cortright, who duly reviewed it with Robert Seamans. The Project Approval Document signed by Seamans on 30 August officially initiated Langley’s first deep – space project. It was given the mundane name of Lunar Orbiter. The Lunar Orbiter Project Office was set up at Langley, with Clifford H. Nelson as Project Manager,2 William J. Boyer as Operations Manager and Israel Taback as Spacecraft Manager. In Newell’s office, Lee Scherer was appointed as Lunar Orbiter Program Director, Leon J. Kosofsky as Program Engineer and Martin J. Swetnick as Program Scientist.

On 30 August 1963 NASA invited bids from industry. In September the Lunar Orbiter Project Office established a Source Evaluation Board chaired by Eugene C. Draley of Langley. Five bids were received. The evaluations began in October and ran to late-November.

A key factor in the requirements was that, where possible, off-the-shelf hardware be used to minimise the development effort. The Hughes Aircraft Company, which was prime contractor for Surveyor and would have built the 3-axis-stabilised orbiter for that project, proposed a spin-stabilised spacecraft that would use a solid rocket

In October 1964 Langley recruited James S. Martin from Republic Aviation as Assistant Project Manager.

Boeing wins 147

motor to enter lunar orbit. The Space Technology Laboratories submitted a refined version of its spin-stabilised design. The Martin Company, which supplied the Titan missile to the Air Force but had limited experience of spacecraft systems, offered a 3- axis-stablised design. The Lockheed Missile and Space Company, which had built the Agena as a 3-axis-stablised vehicle and integrated various payloads into it for the Air Force, including reconnaissance cameras, suggested that the Agena be adapted to operate in lunar orbit. Eliminating the need to develop a new vehicle satisfied the desire for off-the-shelf hardware, but the operational concept was flawed because it would require a lot of propellant to insert such a heavy rocket stage into lunar orbit. The Boeing Company’s expertise was aircraft, but it wished to gain experience with spacecraft systems. It proposed a 3-axis-stabilised spacecraft with a mass of 360 kg that would enter lunar orbit using a liquid rocket (just developed by Marquardt as an attitude control thruster for the Apollo spacecraft) and be powered by solar panels. The Source Evaluation Board was particularly impressed by Boeing’s plan to use a lightweight form of a photographic system developed by Eastman Kodak in I960 for a reconnaissance satellite. The camera used two lenses in a configuration that would take wide-angle and narrow-angle frames simultaneously and interleave them onto a single strip of film.[27] The film would be developed and fixed using the ‘semi-dry’ Bimat process introduced by Kodak in 1961, as this obviated the complication of handling ‘wet’ chemicals in weightlessness.[28] The clinching argument in favour of Boeing was the proposal to use Kodak SO-243 fine-grain aerial film to obtain the required high resolution. This film had an exceedingly ‘slow’ rating of 1.6 ASA, whereas the other bidders intended to use ‘fast’ film. In the case of the spin – stabilised designs, a high-speed film was essential. But adding up the time spent flying to the Moon, the time spent in orbit preparatory to imaging, the 10 days spent imaging, and the time spent scanning and transmitting the film, a mission might last up to a month. During this time there was a fair chance of the particle radiation from a solar storm ‘fogging’ a high-speed film, and the heavy shielding to protect it would be prohibitive. Boeing’s proposal to use slow film showed that the company had a better understanding than its competitors of the mission requirements. The Source Evaluation Board strongly recommended in favour of Boeing, and this was accepted. On 20 December 1963 James Webb announced that the contract would be awarded to Boeing of Seattle, Washington.

Boeing appointed Robert J. Helberg to manage the development of Lunar Orbiter. George H. Hage was Chief Engineer. Carl A. Krafft, the Business Manager, led the contract negotiations that began on 6 January 1964 and involved both Langley and the merged Office of Space Sciences and Applications. Boeing subcontracted Kodak to provide the photographic system, and the Radio Corporation of America for the communications system. In March, Boeing

suggested that the photographic data be processed into pictorial format at Kodak in Rochester, New York, where there was already the necessary equipment, but NASA decided that the processing, handling and distribution of all scientific data provided by Lunar Orbiter should be done at Langley – in the case of photographic data by utilising equipment and technicians supplied by Kodak. Langley appointed Calvin Broome as Chief of the Photographic Subsystem Section.

The plan called for five Lunar Orbiter missions to be launched by Atlas-Agena D, with the first in either late 1965 or early 1966. They were to photograph the lunar surface from a perilune of 40 km. As in the case of Ranger at JPL, Langley would be responsible for overall systems integration of the spacecraft and the launch vehicle, as well as the necessary ground support, but, significantly, by this point NASA had gained control of both the procurement of launch vehicles and of launch operations. Because JPL had established the Deep Space Network to track and communicate with spacecraft, the Lunar Orbiters would be run from the Space Flight Operations Facility. In April 1964, Langley discussed this collaboration with Eberhardt Rechtin. This was the first time that JPL had provided another NASA centre with deep-space support, and so, in effect, a ‘contract’ had to be negotiated to define what JPL would do. But since trajectory design was closely related to the design of the spacecraft’s communications system, and JPL had neither the manpower nor the computer time available to involve itself in this, the transit trajectory and operations in lunar orbit

would have to be planned by Langley and Boeing after JPL had educated Boeing’s engineers in the capabilities and procedures of the Deep Space Network.

Langley and Boeing signed the detailed contract on 16 April 1964. It was sent to NASA headquarters for ratification. James Webb agreed on 7 May, and the formal contract was signed on 10 May.

When NASA decided in 1962 that Apollo would use the lunar orbit rendezvous mission mode, many people doubted that orbital rendezvous would be feasible. The primary objective of the Gemini program was to explore the issues. The ten manned missions flown between March 1965 and November 1966 not only established that rendezvous and docking was feasible, by testing a variety of techniques it gave the Apollo planners the flexibility of options. This inspired a workaround to the fact that the combined Apollo vehicles exceeded the payload capacity of the Saturn IB, in the form of the dual AS-207/208 rendezvous. Gemini also showed that astronauts could endure the space environment for longer than any Apollo mission would require. Given that the longest American space flight at the time of President Kennedy’s commitment to Apollo was Al Shepard’s 15-minute suborbital arc, on which he was weightless for only a couple of minutes, this was welcome news. The fuel cells that were to power the Apollo spacecraft were tested on Gemini, as were a fully inertial reference platform for guidance and navigation, a spaceborne radar, a state-of-the-art digital computer to process the radar data for rendezvous, and bipropellant ablative thrusters. Gemini established that a spacecraft could be steered through re-entry for recovery at a specific location. This increased confidence in the ‘atmospheric skip’ manoeuvre that was to be used by an Apollo spacecraft returning from the Moon. By enabling astronauts to learn how to operate outside a spacecraft, Gemini inspired a rescue option for the crew of an Apollo lunar module that was unable to dock with its mothership. And, of course, by training a cadre astronauts and flight controllers Gemini allowed Apollo to get off to a running start.

As Robert Gilruth, Director of the Manned Spacecraft Center, observed: ‘‘In order to go to the Moon, we had to learn how to operate in space. We had to learn how to manoeuvre with precision to rendezvous and to dock; to work outside in the hard vacuum of space; to endure long-duration in the weightless environment; and to learn how to make precise landings from orbital flight – that is where the Gemini program came in.’’

EARLY IDEAS ABOUT LUNAR CRATERS

In 1662 Robert Hooke was made curator of the recently formed Royal Society of London. He was charged with devising demonstration experiments. As an extremely skilled technical artist, in 1665 he published Micrographica, which was profusely illustrated with his own observations using a telescope and a microscope. Although he included a detailed drawing of the lunar crater Hipparchus, which is at the centre of the Moon’s disk, he had no desire to map the Moon. However, he undertook a series of experiments to investigate how craters may have formed. First he dropped heavy balls into tightly packed wet clay, and examined the imprints that they made. He also heated alabaster until it bubbled, and then let it set so that the last bubbles to break the surface produced craters. However, just as Hooke could not imagine where the projectiles could have come from to scar the Moon so intensively, nor could he conceive how the surface could have been sufficiently hot to blister on such a scale.

Following the discovery of the first two asteroids in 1801 and 1802, Marshal von Bieberstein in Germany suggested that lunar craters were created by the impact of such bodies. This was reiterated independently in 1815 by Karl Ehrenbert von Moll. In 1829 Franz von Gruithuisen agreed. However, the idea was rejected by those who supported the anti-catastrophist paradigm of uniformitarianism in terrestrial geology which was developed in the 1830s and 1840s.[4] In 1873 Richard A. Proctor published The Moon. Although this book was largely devoted to the motions of the Moon, he revived the idea that the craters marked impacts. But when the second edition of the book was issued in 1878 this section had been deleted. What puzzled the nineteenth century proponents of the impact hypothesis was that the lunar

craters are almost all circular, whereas the majority of bodies must have struck at an oblique angle and, it was presumed, produced elliptical craters.

In 1874 James Nasmyth and James Carpenter in England published The Moon, in which they attempted to explain how the surface features may have formed. As had Hooke two centuries earlier, they made model craters in experiments. They came to the conclusion that the lunar craters were produced by ‘fountains’ of material. In the early part of an eruption, when the velocity of the material ejected from the vent was great, the material would spray out in an umbrella-shaped plume and fall back some distance away to build up a concentric ring that became the wall of the crater. In many cases, as the eruption declined the fallout formed a succession of terraces interior to the wall. They presumed that in some cases the final phase of the eruption either built up the central peak, or in the case of craters with dark floors and no peak, switched to fluid lava that was confined to the cavity and buried the vent. In view of the weak gravity and absence of an atmosphere, it seemed plausible that this process could have produced very large structures.

Other explanations were offered for the origin of lunar craters. In 1854 the Danish astronomer Peter Andreas Hansen argued that the Moon bulged towards Earth, that its centre of gravity was displaced 50 km towards the far-side, and that this had drawn all the air and water on the surface around to the far-side, to where the inhabitants had relocated. In 1917 D. P. Beard suggested that the Moon was once immersed in a deep ocean, that the craters were limestone structures similar to coral reefs, and they were left exposed when the water flowed to the far-side.