Category The First Men on the Moon

Orbital investigations

With Ranger, JPL had seized the initiative in the development of space probes for missions in deep space. In May 1960 it took on a much more adventurous project to develop two related spacecraft: one to enter lunar orbit to conduct mapping and the other to land. Unfortunately, the development of the powerful Centaur stage to dispatch these new probes proved protracted. In coming to terms with Kennedy’s time scale for Apollo, NASA cancelled JPL’s mapper, and instructed the Langley Research Center to build a lightweight orbiter capable of being dispatched by the Atlas-Agena. This new spacecraft was not to be a global mapper, it was simply to chart predetermined areas as potential Apollo landing sites. This unimaginatively named Lunar Orbiter project was initiated in August 1963. Although Ranger had yet to prove itself, it was apparent that developing an orbiter would not just be a matter of fitting a motor to insert Ranger into lunar orbit. While JPL’s television camera package was ideal for documenting a 20-minute plunging dive that would result in the destruction of the craft, it was capable of providing the required high surface resolution only in its final few seconds, by which time its field of view was extremely constrained. To survey wide areas with such resolution from an altitude of 35 nautical miles, Lunar Orbiter would expose film that would be developed, scanned and transmitted back to Earth. Furthermore, since the orbiter had to be lightweight, the camera could not be heavily shielded from radiation in space, and very fine-grained ‘slow’ film was employed, which in turn necessitated long exposures and a mechanism to enable the camera to compensate for the spacecraft’s motion. A twin-lens system was used, with the images from a wide lens providing the context for those from a narrower lens. In December 1963, at the same time as it cancelled the follow-on Rangers, NASA awarded the contract for Lunar Orbiter to Boeing; in effect, the budget was transferred. As with Ranger, Lunar Orbiter would fly as a 3-axis stabilised platform, but a spacecraft’s configuration is intimately related to its payload and although it was possible to use many off-the-shelf systems, the orbiter was necessarily very different from its predecessor. The budget allowed for five operational spacecraft, plus a spare for engineering trials. It was expected that three successful flights would be sufficient to survey all the candidate sites for the first Apollo landing, which was as far ahead as the agency was thinking at the time. To achieve this, Langley wrote three flight plans, designated ‘A’, ‘B’ and ‘C’.

Lunar Orbiter was to fly an almost equatorial elliptical orbit with a 35-nautical – mile perilune on the near side timed to enable the spacecraft to expose its pictures at a low Sun angle to highlight the surface relief, and let the perilune point drift to more western longitudes to follow the sunrise terminator. After 10 days the perilune point would have travelled the length of the equatorial zone in which the targets were located, documenting each under ideal illumination. Furthermore, because the zone extended 80 nautical miles to each side of the equator, it was necessary to tilt the trajectory. In fact, it was decided to adopt an inclination of 11 degrees for the first two missions, with the perilune of the first south of the equator and the perilune of the second north of the equator, and then incline the orbit of the third mission as required to fill in gaps and make follow-up studies.

Lunar Orbiter 1 was launched on 10 August 1966, and entered lunar orbit on 14 August. A motion compensator fault smeared the pictures from the narrow lens. Although the flight controllers considered raising the perilune in order to reduce the smearing and map the entire Apollo zone with a resolution of about 80 feet, it was decided to remain at low level and document the designated targets using the wide lens. On 29 August the spacecraft photographed the ninth target on its list, processed its film and transmitted the results, thereby completing its primary mission. It transmitted telemetry for a further two months to enable the degradation of its systems to be monitored, and was then de-orbited to clear the radio frequencies for its successor, which began its program on 18 November. In addition to inspecting the remaining 11 candidate targets, Lunar Orbiter 2 was able to snap a number of secondary sites which, while of no immediate interest to the Apollo planners, were of ‘scientific’ interest and possible candidates for later missions. Lunar Orbiter 2 completed its photography on 26 November. In addition to its own targets, it had taken high-resolution images of the most interesting sites photographed at medium resolution by its predecessor. Site ‘A3’ (now labelled 2P-6) was confirmed to be promising and (of the new targets) 2P-2 was deemed to be suitable. In addition to photographing the most promising targets from different angles in order to permit stereoscopic analysis of the topography, Lunar Orbiter 3 charted the routes that an Apollo spacecraft might fly to approach these sites. The US Geological Survey (USGS) produced terrain maps for the Apollo planners.

With the primary objective of the project achieved by the first three spacecraft, NASA released the remaining spacecraft to the scientists, who opted to fly them in near-polar orbits at higher altitudes in order to conduct more general mapping, particularly of the far side of the Moon which permanently faces away from Earth. Even after they had finished imaging, this series of spacecraft provided insight into the lunar interior. Although Lunar Orbiter 1 was de-orbited prior to the arrival of its successor, it was noted that its orbit was being perturbed, indicating that the Moon’s gravitational field was uneven. To study this phenomenon, the subsequent spacecraft were not de-orbited until their attitude-control propellant was almost exhausted, and by virtue of flying vehicles in both equatorial and polar orbits it was possible to chart the field in sufficient detail to infer that the dark plains in the circular basins were the loci of the most intense gravity. The discovery of these ‘mascons’ (i. e. the excess of mass concentrated in these basins) was fortunate, as otherwise their perturbations of the Apollo mission would have come as a surprise.

READY TO GO

On flying back to the Cape on Monday, 7 July, the astronauts returned to the semi­isolation of their quarters in the Manned Spacecraft Operations Building, going out only to use the simulators in a nearby building. On 10 July, having been medically checked, Tom Paine had a private dinner with the astronauts at which he implored of them, “If you get into trouble up there, do not hesitate to abort. Come on home. Don’t get killed. If you do have to abort, I promise this crew will be slipped ahead in the mission sequence. You’ll get another chance. Just don’t get killed.’’ Collins reflected that Paine’s motivation was to eliminate “the obvious risk of letting our desire to be first on the Moon cloud our judgement in analysing the hazards’’. In fact, Paine had said the same to the crews of Apollo 8 and Apollo 10. Earlier that day, after tests had indicated an oxygen leak in the first stage of the launch vehicle, Walter Delle, a Boeing quality inspector, entered the tank and tracked the ‘hiss’ to the helium pressurant manifold. As this was such a delicate item, it was debatable which would be the least risky option: to accept the leak, or attempt to eliminate it. It was decided to try to stem the leak by applying torque to a nut using a wrench. If the manifold were to be damaged in the process, replacing it would take four days, which would require the launch to be postponed. But Delle was successful, and the final review cleared the mission to aim for launch on 16 July.

The week before launch, Charles Berry mentioned to a reporter that President Nixon had asked to have dinner with the crew on the night before launch, as Vice President Spiro T. Agnew had done with the Apollo 10 crew. Berry had stated that Nixon’s presence at such a late stage would prejudice the crew health stabilisation program, since if the Apollo 11 crew were to return with an infection it would be essential to know whether this had been contracted prior to their leaving Earth in order to enable it to be dismissed as a potential lunar infection. In fact, considering that the launch of Apollo 9 had had to be postponed several days to allow its crew to recover from a mild upper-respiratory infection, it was remarkable that Agnew had been permitted to visit the Apollo 10 crew, since they would be in deep space by the time any symptoms that would have given rise to a postponement became manifest. However, NASA headquarters took the view that Berry’s opinion was merely his recommendation; it was not for him to decide whether anybody could visit the crew. Frank Borman, assigned as space adviser to Nixon for Apollo 11, said the dinner should go ahead, since it would be a tremendous boost to crew morale. However, because the matter was now in the public domain, Nixon deferred. If an astronaut were to fall sick in space, Nixon would be open to the damning criticism of callously disregarding the professional advice of the chief flight surgeon. Although the press habitually referred to Berry as the astronauts’ personal physician, he was Director of

Medical Research and Operations at the Manned Spacecraft Center. The final comprehensive medical examination of the astronauts was on Friday, 11 July by the physicians assigned to this mission: Al Harter, Jack Teegan and Bill Carpentier. The aim was to evaluate their biological state of heath by comparing the organisms in their systems with the ‘baseline’ established on 26 June. In the early days, nurse Dee O’Hara had taken blood and urine samples of departing astronauts, but as these tasks were now done by technicians she was responsible for the paperwork – which amounted to 18 pages per man. As a result of this examination, the crew was declared fit to fly. All that remained, medically speaking, was the basic check-up on the morning of launch.

Over the weekend, the pace slackened. They continued to use the simulators, but for proficiency rather than for training, and undertook a final review of the flight plan. Ted Guillory had supervised the writing of the 240-page flight plan for Apollo

11. It weighed 2 pounds, and addressed every aspect of the mission for a nominal duration of 195 hours 40 minutes. Two copies would be needed, one for the CSM and the other for the LM. In addition, there would be some 20 pounds of reference material on board. The general consensus was that the astronauts had reached their ‘peak’ right on time. As Aldrin observed: ‘‘We could spend another year trying to isolate [the open issues] one by one, and we’d never really get them all. We could spend too much time doing that, so much that we could forget what the mission is all about.’’ On 16 May the first draft of the mission rules was issued. Updated weekly, by the time of launch it had expanded into a 350-page book that defined the actions to be taken in the event of a multitude of situations arising in flight. As such, it formalised the collective knowledge of all concerned.

Soon after Apollo 8 set off for the Moon Frank Borman had suffered a bout of ‘space sickness’, which came as a considerable surprise in view of the fact that he had he spent 14 days on board Gemini 7 in December 1965 with no ill effects. Rusty Schweickart suffered similarly on Apollo 9. It seemed that in the confined Gemini spacecraft astronauts had not been able to become disoriented, but by being able to move around in the much larger Apollo cabin they could develop motion sickness. In an effort to prime the vestibular mechanism of his inner ear for weightlessness, Collins drove down the coast to Patrick Air Force Base and flew aerobatically in a T – 38 for an hour each day over the final weekend. Aldrin flew zero-gravity arcs in the KC-135 several days later, in the hope of doing the same.

The hot news on Sunday, 13 July, was the announcement by the Soviet Union that it had launched the unmanned spacecraft, Luna 15. The speculation was that this would land on the Moon, scoop a sample, and return this to Earth. There was some concern in NASA that the spacecraft’s transmissions might interfere with Apollo 11. Since his Apollo 8 flight, Frank Borman had spent much of his time in Washington as Nixon’s space adviser and undertaking goodwill tours. Three days earlier, he had returned from a 10-day trip to the Soviet Union, and was in fact, the first astronaut to visit that country. On a Washington stopover that afternoon he received a message from Chris Kraft in Houston requesting that he use his recent contacts to gain information on the Luna 15 mission. Borman called the office of Mstislav V. Keldysh, the 68-year-old leader of the Soviet Academy of Sciences.

However, as it was 2 am in Moscow, Borman left a message and then returned to Houston. At 6 am the following morning he received a phone call from Keldysh’s office reporting that the information was en route, and several hours later identical telegrams arrived at his home and at the White House specifying the orbit intended for Luna 15 and confirming that there would be no radio interference. In view of the rivalry between the space-faring nations, this was welcome cooperation. Even if Luna 15 returned only a few ounces of lunar material, the Soviets would be able to claim that they had ‘beaten’ America as long it returned ahead of Apollo 11. The stakes were therefore high. Wernher von Braun told a reporter that although the Soviets had lost the ‘race’ to send a man, their attempt ‘‘to soft land a spacecraft on the Moon and scoop up a sample of lunar soil and fly it back to Earth’’ represented a tremendous technical challenge, in which he wished them ‘‘full success’’ even though it would ‘‘take a little bit off our program’’. Then he made the telling point that such a mission could be no impromptu effort, because ‘‘to have the hardware ready, it would have had to have been planned… years earlier’’.

In July, the afternoon temperature at the Cape regularly rose to 100°F, and the combination of heat and ocean humidity made conditions almost unbearable. The Sun blazed down day after day. The concrete was so bright that sunglasses were mandatory. But on Sunday, 13 July, it started to rain and the forecast was for several days of poor weather. Thus, even if everything else was ready, the weather might oblige the launch to be postponed, possibly to August.

On Monday, 14 July, Robert Gilruth, George Low, Deke Slayton, Chris Kraft and Max Faget flew to the Cape for the final flight readiness review, which, as expected, confirmed the launch date. At 5 pm the terminal countdown was picked up with the clock at T-28 hours, with two built-in ‘holds’ (the first to start at T-9 hours and last for 11 hours, and the second to start at T-3 hours 30 minutes and last for 1 hour 32 minutes) with a view to launching as the window opened for the primary landing site, which was 9.32 am local time on Wednesday, 16 July.

Tranquility Base

POST-LANDING ACTIVITIES

The flight plan called for the moonwalk to start about midnight Houston time. The idea had been to accommodate the possibility of the landing being delayed by one revolution, and still give Armstrong and Aldrin a period in which to wind down before starting the EVA preparations. However, as Armstrong reflected, “We had thought, even before launch, that: if everything went perfectly and we were able to touch down precisely on time; if we didn’t have any systems problems to concern us; and if we found that we could adapt to the one-sixth gravity lunar environment readily; then it would make more sense to go ahead and complete the EVA while we were still wide awake – but, in all candour, we didn’t think this was a very high probability.’’ Nevertheless, some 2 hours after landing, Aldrin called Houston, “Our recommendation at this point is to plan the EVA, with your concurrence, to start about 8 o’clock Houston time; that’s about 3 hours from now.’’

“Stand by,’’ responded Duke.

“Well,” said Aldrin, “we’ll give you some time to think about that.’’

But half a minute later Duke was back, “We’ve thought about it; we’ll support it. You’re Go at that time.’’ A moment later, he sought clarification, “Was your 8 o’clock Houston time a reference to opening the hatch, or starting the preparation for the EVA at that time?’’

“That would be hatch opening,’’ Armstrong replied.

“That’s what we thought.’’

But Armstrong then decided to play safe, “It might be a little later than that; in other words, we’ll start the preparations in about an hour or so.’’

Meanwhile, during his first pass overhead Collins had tried to see Eagle on the surface. As Columbia approached the general area of the landing site, he told his computer to slew the sextant onto the coordinates that Duke had given him. With the sextant maintaining the line of sight, he looked for either the momentary solar glint reflecting off the foil covering the vehicle, or the distinctive narrow shadow that it would project; but he saw neither. At his altitude of 69 nautical miles the 1.8- degree-wide circular field of view of the sextant covered an area of only a few square miles, and orbiting at almost 3,700 nautical miles per hour he was above 45 degrees

elevation for less than 2 minutes 30 seconds, which was barely enough to study the designated location – it was certainly insufficient time to slew the sextant around to conduct a search.

“How did Tranquility look to you down there?” Duke enquired afterwards.

“Well,” replied Collins, “the area looks smooth, but I was unable to see them.” As an afterthought, he added, “It looks like a nice area, though.”

Windler’s Maroon Team took over in order to deal with the EVA preparations, with Owen Garriott as CapCom.

“Columbia,” called Garriott, “Tranquility Base are prepared to begin the EVA early; they expect to begin depress operations in about 3 hours, at approximately 108 hours.’’

“Tell them to eat some lunch before they go,’’ recommended Collins.

About 20 minutes later, Armstrong and Aldrin reached the point in their flight plan at which they could doff their helmets and gloves. Their next item was to be lunch which, since there was no provision for hot water in Eagle, would be a cold snack. First, however, Aldrin had an item of his own. A month previously, he had asked Dean Woodruff, the minister at the Webster Presbyterian Church, “to come up with some symbol that meant a little bit more than what most people might be thinking of [immediately after the landing]’’, and they had decided that Aldrin should celebrate the Sacrament of Holy Communion. When Aldrin told Deke Slayton of this, Slayton reminded Aldrin that Apollo 8’s reading from Genesis had resulted in a law suit, and asked that he refrain from making overtly religious remarks.[32]

“This is the LM pilot,’’ Aldrin called. “I would like to take this opportunity to ask every person listening in, whoever and wherever they may be, to pause for a moment and contemplate the events of the past few hours and to give thanks in his or her own way.’’ Listening to her squawk box, his wife recognised the significance of his invitation for people to celebrate. He then switched off his microphone and drew from his personal preference kit a small silver chalice, a vial no larger than his little finger with a symbolic amount of wine, and a wafer representing bread loaf. Using the fold-down shelf in front of the DSKY as his altar he poured the wine, in the process observing that the fluid swirled around in the chalice for an inordinate time in the weak lunar gravity. He then read a card on which he had written the verse from the Book of John (15:5) traditionally used for this event: I am the vine, you are the branches; he who remains in me, and I in him, will bear much fruit; for apart from me you can do nothing. Communion was appropriate because it was a Sunday. Armstrong, who had been alerted in advance, watched in respectful silence. Unfortunately, NASA’s hope that the ceremony would remain private was foiled by the Reverend Woodruff himself, who told a reporter that he had supplied Aldrin with a Communion kit.

When the time approached at which it had been estimated that the astronauts might initiate their EVA preparations, with there having been no communications since Aldrin’s call, Garriott prompted, “We’d like some estimate of how far along you are with your eating, and when you may be ready to start your preparations.”

“I think we’ll be ready to start in about half an hour or so,’’ Armstrong said. With that, the circuit reverted to silence.

In fact, preparing for the excursion proved to be rather more time consuming than expected. In training, the cabin had been ‘clean’, with just the apparatus for the exercise present, but in reality the cabin held everything they would require for the mission, and 90 minutes had elapsed before they were ready to begin the EVA preparations, and then activities that were assigned 2 hours actually took 3 hours. It was therefore fortunate that they had opted to forgo the early rest period.

Meanwhile, Charlesworth’s Green Team took over, with Bruce McCandless as CapCom. He directed his attention to Columbia. Collins had inspected the second estimated position of the landing site, again in vain. While he would continue with these efforts, it dawned on him that although it was evident that Eagle was in the western half of the ellipse, the scatter in the estimated positions meant that Mission Control did not really know where it was.

Surface investigations

As the mechanical properties of the lunar surface would influence the design of the LM the Apollo planners said, in October 1962, that the development of JPL’s ‘soft landing’ spacecraft should receive a higher priority than the orbital spacecraft. However, the development of the Centaur stage was so protracted that the surface investigations could not start until 1966. The planners for these Surveyor missions were faced with the same dilemma as their Apollo counterparts: where should they send their first mission? Although safety issues obliged them to select one of the dark plains, this was consistent with characterising the surface in the equatorial zone in which the Apollo targets were located. When Surveyor 1 was launched on 30 May 1966, the ‘old hands’ at JPL might well have wondered whether they were in for a rerun of the teething troubles that had plagued Ranger, but on 2 June the spacecraft landed safely near Flamsteed, in a crater that appeared to have been breached by the Ocean of Storms. As with Ranger, the single instrument was a television camera. Its first picture showed the spacecraft’s foot pad resting on the surface, which was barely indented. It then proceeded to take a multitude of individual frames from which a panoramic mosaic was later produced. There was a profusion of small craters and rocks, but the area was generally flat. Although the site seemed to be consistent with a flow of low viscosity lava, this was disputed. The camera continued to send panoramas to document the appearance of the surface under different illumination, and then the solar-powered spacecraft went into hibernation for the long lunar ‘night’ – and, to everyone’s surprise, not only did it awaken with the return of the Sun, it did so each ‘morning’ for the rest of the year. Having succeeded at the first attempt, the engineers were disappointed when Surveyor 2 tumbled during a course correction on its way to the Moon, and was lost. On 20 April 1967 Surveyor 3 set down in a 660-foot-diameter crater in the

Ocean of Storms, bouncing several times prior to coming to a halt. The inner wall was pocked by smaller craters, one of which had excavated large blocks of rock. This vehicle had an arm with which to determine the mechanical properties of the loose surficial material, dig trenches to reveal the subsurface, and roll rocks to determine the extent to which their state of erosion was selective. In contrast to its hardy predecessor, Surveyor 3 survived only one lunar night. Next, contact was lost with Surveyor 4 several minutes before it was scheduled to land. Having sampled two dark plains in the western hemisphere and failed twice to reach a site on the meridian, JPL dispatched Surveyor 5 to sample the Sea of Tranquility. It landed on 11 September 1967, just 14 nautical miles from the 2-P6 site on the short­list for the first Apollo landing. Instead of an arm, it had an instrument to investigate the chemical composition of the surficial material. After taking one reading, the spacecraft ‘pulsed’ its thrusters in order to ‘hop’ several feet, to sample a second patch. The results indicated calcium, silicon, oxygen, aluminium and magnesium, which implied basalt, but the high ratios of iron and titanium meant that the lunar basalt was subtly different from its terrestrial counterpart. Surveyor 6 was sent to the Meridian Bay to fill in for its lost forerunners, and landed without incident on 10 November 1967. The results of its chemical analysis indicated an iron-rich basalt. Since the dark plains across the Apollo landing zone had proved to be remarkably similar, NASA released the final spacecraft to the scientists, who decided to send it to Tycho, a bright ‘ray’ crater in the southern highlands, where it landed on 10 January 1968. By cutting margins, JPL enabled it to employ both the robotic arm and the chemical analyser – which proved fortunate because the analyser became stuck, and if it were not for the arm nudging it free the scientific study would have been undermined. In addition, rather than make the spacecraft hop so as to sample different patches of surface, the arm was used to place the instrument on a patch of excavated soil in order to check that this was the same as the material on the surface, and later to place it on top of a rock. Some researchers interpreted the elemental abundance data to mean that the lunar highlands were an alumina-rich basalt, but Eugene M. Shoemaker, head of the Astrogeology Branch of the USGS, argued that the dominant rock in the Tycho ejecta was anorthositic gabbro, which had interesting implications.2

Translunar coast

RETRIEVING EAGLE

Immediately after the TLI manoeuvre, the S-IVB adopted an orientation calculated to yield favourable illumination for the separation of the CSM and its subsequent transposition, docking and extraction (TD&E) of the LM. Armstrong yielded the left-hand couch to Collins who, as CMP, had trained for this delicate operation. The reaction control system (RCS) comprised four units at 90-degree intervals on the side of the service module, each with a cluster of four rocket thrusters that could be fired separately or in various combinations to control roll, pitch and yaw motions. During the climb through the atmosphere, the conical adapter mounted on top the S-IVB was allowed to vent to ensure that there would be no sudden release of air when the spacecraft separated.

“You’re Go for separation,” called Bruce McCandless, 3 hours 15 minutes into the mission.

After using the left-hand translational controller to start the aft-facing thrusters, Collins threw a switch to detonate pyrotechnic charges around the rear rim of the service module to detach that module from the adapter. Once a display indicated that he was moving at about 1 foot per second, he ceased to thrust. Meanwhile, the four panels of the adapter hinged open like petals and then detached to drift away. After 15 seconds, he used the right-hand rotational controller to initiate a 2-degree-per-second pitch motion. When so instructed, the digital autopilot was to maintain this angular rate but, to his frustration, it cancelled the rotation and adopted a fixed attitude. He had to repeat the procedure several times before the autopilot accepted the rotation. In consequence, the rotation used rather more propellant than planned. The issue was later determined to be procedural in nature. Once the spacecraft was facing the S-IVB, Collins terminated the rotation and fired the aft-facing thrusters again, this time to halt 100 feet out, whereupon he fired them a third time in order to move back in.

“I hope you’re getting some pictures, Buzz,’’ Armstrong said.

“I’ve got the 16-millimetre going at 16 frames per second,’’ confirmed Aldrin, referring to the Maurer camera he had mounted in window 4. The LM was clearly visible, supported within the annular ring near the base of the adapter by fixtures on its folded legs.

“Be sure that your RCS is working,” Armstrong prompted Collins, to confirm that the forward-facing thrusters to be used for braking were functional, because if they failed the CSM would smash into the LM. When Collins did so, he noted that the efflux rippled the aluminium thermal shielding of the ascent stage, and hoped he wouldn’t damage it.

The extended probe on the apex of the spacecraft was not visible through the small forward-facing window, but Collins did not need to see it as there was a ‘stand off target on the roof of the LM which, when correctly viewed, meant that the probe was centred on the conical drogue. With the Sun over his shoulder, the roof of the LM was nicely illuminated. In easing the probe into the drogue, Collins was conscious that his vehicle had a mass of 65,000 pounds, and that the 33,000-pound LM was attached to the ‘dead weight’ of the spent S-IVB. As the probe penetrated the socket at the apex of the cone, three small capture latches around the tip of the probe automatically engaged for a ‘soft docking’. When he was sure that the vehicles were lined up, Collins threw a switch and a discharge of nitrogen gas pneumatically retracted the probe, in the process drawing the two collars together and triggering 12 spring-loaded latches that established a rigid connection, or ‘hard docking’.

Although the docking was accomplished, Collins was dissatisfied. ‘‘That wasn’t the smoothest docking I’ve ever done.’’

‘‘Well, it felt good from here,’’ Armstrong complimented.

‘‘I mean the gas consumption,” explained Collins. He had used rather more fuel during the transposition manoeuvre than expected.[19]

While manoeuvring, the quality of signal using the omnidirectional antennas had degraded to the point at which communication became impractical. Aldrin operated the controls to slew the high-gain antenna mounted on a boom on the rear of the service module to point its beam towards Earth to restore communications; once locked on, the system would steer itself to maintain maximum signal strength as the line of sight evolved.

The 30-inch-diameter tunnel to the LM ran through the apex of the command module. As per the plan, an open valve in the LM’s overhead hatch had allowed its cabin to vent. Having already raised the pressure in the command module, Collins opened a valve to allow oxygen to pressurise the tunnel, and thence the LM. On opening his hatch, he noted an odour reminiscent of charred electrical insulation, but all the exposed wiring in the tunnel appeared to be factory fresh and he pressed on with his checklist, jiggling each of the docking latches by hand to confirm that it was properly engaged.

In 1958 America’s first satellite, Explorer 1, discovered that there is an intense belt of charged-particle radiation present within the Earth’s magnetic field. In fact, as subsequent satellites revealed, there is an inner belt of high-energy protons and an outer belt of electrons. These ‘radiation belts’ were named after the scientist who

A depiction of the inner and outer van Allen radiation belts.

supplied the instrument that made the initial discovery – James van Allen of Iowa University. The proton belt would pose a severe health risk to any astronaut unwise enough to linger within it, but fortunately it was concentrated above the equatorial zone and extended out only a few thousand miles, and because the Moon orbits Earth at an angle to the equator Apollo 11 was able to avoid the most intense part of this belt. Also, as with any object that is thrown upwards in Earth’s gravity, as soon as the S-IVB shut down its engine it began to slow as it pursued a ballistic trajectory. At that time it was at an altitude of 177 nautical miles and was climbing at 21,345 nautical miles per hour. When Collins separated the CSM from the S-IVB, their altitude was over 3,000 nautical miles, and this distance had doubled by the time he completed the transposition and docking 10 minutes later. The radiation received was therefore no worse than that involved in having a chest X-ray. The radiation within the Earth’s magnetic field originates from the ‘solar wind’, which is a flow of charged particles emanating from the Sun. This was discovered in 1962 by Mariner 2, the first spacecraft to report on conditions beyond the realm dominated by the Earth’s magnetic field. Cislunar space – the environment between Earth and the Moon – is comparatively benign, unless a ‘solar flare’ directs a blast of charged-particle radiation in our direction. In terms of sun spots, the intensity of solar activity varies with an 11-year periodicity and, in fact, 1969 was a risky time to be heading for the Moon!

Looking back at Earth, which was rapidly shrinking, Armstrong displayed his keen sense of geography – a childhood passion. Their departure trajectory offered a better view of the northern hemisphere than of southern latitudes. ‘‘Houston,’’ he called, ‘‘you might be interested that out of my left-hand window right now, I can observe the entire continent of North America, Alaska and over the pole, down to the Yucatan peninsula, Cuba, the northern part of South America – and then I run out of window.’’

The number of sunspots follows a roughly 11-year cycle.

Meanwhile, Collins had inserted electrical plugs to feed power through to the LM’s heaters and to pyrotechnics in the adapter. McCandless gave them the go – ahead to retrieve the LM. Precisely one hour after initiating the transposition and docking sequence, and now 12,600 nautical miles from Earth, Collins fired the charges to release the LM, and springs eased the 98,000-pound docked spacecraft away from the spent stage. If the charges had failed, the CSM would have undocked and gone on to fly an Apollo-8-style mission in lunar orbit, but this would have been a poor consolation.

The next task, some 20 minutes later, was to perform a manoeuvre to increase the rate of separation from the spent S-IVB. The cutoff velocity at TLI had been set marginally faster than that of the ideal trajectory, with the intention of using the service propulsion system (SPS) of the CSM to cancel the excess. This engine had been designed in such a manner that it was unlikely not to fire, but it was wise to test it early on. Delivering 20,500 pounds of thrust, it would be able to impart the desired velocity change (delta-V) of 19.7 feet per second in 3 seconds, which was just long enough for the telemetry to verify the propellant supply, the combustion chamber pressure and the stability of the gimbal. There was no need for an igniter because the hydrazine-based fuel and nitrogen tetroxide, being hypergolic, ignited immediately on coming into contact after being fed through a pattern of holes in the injector into the combustion chamber.

After running through the post-burn checklist, Armstrong returned to the view of Earth. “We didn’t have much time to talk about the view out the window when we were preparing for LM ejection, but up to that time we had the entire northern part of the day hemisphere visible – including North America, the North Atlantic, and Europe and the northern region of Africa. There was a cyclonic depression over northern Canada, east of Athabasca. Greenland was clear, and it appeared that we were seeing just the icecap. All of the North Atlantic was pretty good. And Europe and northern Africa seemed to be clear. Most of the United States was clear. There was a low, it looked like a front, stretching from the centre of the country, up north of the Great Lakes and on into Newfoundland.’’

“I didn’t know what I was looking at,’’ added Collins, “but I sure did like it!’’

“The view must be pretty good from up there,’’ McCandless agreed. “We show you about 19,000 nautical miles out now.’’ Although this was the altitude at which satellites in geostationary orbits reside, Apollo 11 was far above the plane in which such satellites operate.

If the S-IVB were to pursue the trajectory established by TLI, then it, like the spacecraft, would pass just in front of the leading limb of the Moon. To eliminate any possibility of a collision in transit, once Apollo 11 was clear of it, the ground commanded the S-IVB to execute a venting process designed to deflect its path to pass close by the trailing limb for a gravitational ‘sling shot’ into solar orbit. This venting would involve several phases over the period of about 40 minutes, and the planners had worked out how the spacecraft should be oriented to enable the crew to observe it.

‘‘We’ve completed our manoeuvre to observe-the-slingshot attitude,’’ Collins reported, ‘‘but we don’t see anything – no Earth, and no S-IVB.’’ Houston provided a revised attitude, and Collins started the manoeuvre, but because he had not only used more propellant than expected during the transposition and docking, but had also undertaken a fruitless manoeuvre, he initiated this new manoeuvre at a slow rate.

The venting could not be postponed because, once commanded, the Instrument Unit could not be interrupted. ‘‘It doesn’t look to us like you will be able to make it around to the observation attitude in time,’’ McCandless warned. ‘‘We recommend that you save the fuel.’’

‘‘Our manoeuvre has already begun,’’ pointed out Collins, ‘‘so it’s going to cost us about the same amount of fuel to stop it no matter where we stop it, and we may as well keep going.’’

‘‘We’ve got the S-IVB in sight at what I would estimate to be a couple of miles away,’’ announced Aldrin several minutes later. ‘‘The dump appears to be coming out at radially opposite directions.’’ As this preliminary part of the sequence was to be non-propulsive, the stage was venting oxidiser from opposite sides at the rear. About 25 minutes later, the venting was switched to occur through the J-2 engine, but by then the S-IVB was no longer visible. Finally, the two auxiliary propulsion system modules on the rear of the stage were fired to complete the manoeuvre.

As McCandless read up instructions to reconfigure the fuel cells that generated electrical power, the astronauts started their first meal. ‘‘If we’re late in answering you,’’ Collins apologised, ‘‘it’s because we’re munching sandwiches.’’

‘‘I wish I could do the same here,’’ said McCandless.

‘‘No. Don’t leave the console!’’ Collins warned. ‘‘Flight doesn’t like it. How is he today?’’ The flight director was Clifford Charlesworth, and Collins had served as his CapCom during the Apollo 8 mission.

‘‘Oh, he’s doing quite well,’’ McCandless laughed.

‘‘I think today is the birthday of California,’’ Armstrong called. ‘‘I believe they are 200 years old, and we send them a happy birthday. I think it is also Dr George Mueller’s birthday, but I don’t think he’s that old!’’ George E. Mueller, Director of the Office of Manned Space Flight, was celebrating his 51st birthday.

Six hours into the mission, Charlesworth’s Green Team handed over to Gene Kranz’s White Team, and Charlie Duke took over as CapCom. After crossing the road to brief the press in the News Center, Charlesworth joined his controllers in the ‘Singing Wheel’, a red-painted wooden barn of a building that housed the bar that served as a ‘watering hole’ for off-shift flight controllers heading home.

Having taken sextant sightings to realign the inertial platform, Collins initiated a deep-space navigation test. This P23 exercise required him to measure the angles of five stars relative to Earth’s horizon. In each case, the computer was to orient the vehicle to enable the sextant to measure from the ‘substellar point’. However, the system was not aligning properly, and a measurement along a line that was not perpendicular to the horizon would yield an inaccurate result. The technique was valid, it was simply that something had gone amiss in planning. But he persevered because the data would help the engineers to determine the problem. The test was scheduled at this time in order to confirm the ability to make such measurements before the spacecraft was so far away that Houston could not provide a check. This technique was intended primarily for navigating the approach to re-entry, in order to provide a contingency against loss of communications on the way home.

Meanwhile, first Aldrin and then Armstrong doffed their pressure suits. It was a dynamic process involving a colleague unzipping the rear of one man’s suit and holding him stable while he squeezed out. After finishing his navigation exercise, Collins joined them. With the various parts of the three suits adrift, there was, as Aldrin later put it, ‘‘a great deal of confusion, with parts and pieces floating about the cabin as we tried to keep the logistics under control’’. The suits were carefully folded, stuffed into storage bags and stowed beneath a couch. It was a great relief to remove the urine-collection and fecal-containment devices, which were stowed in a locker in the lower equipment bay. There was no toilet. Urination would be through a tube into a plastic bag that would be periodically vented overboard into vacuum. Defecation would involve the use of a plastic bag, part of which fitted over the hand like a glove. When finished, a germicide pill would be inserted into the bag to prevent bacteria generating gas. This ‘glove bag’ had proved effective on Gemini flights, when, because of the pill, it was euphemistically referred to as a ‘blue bag’. Used bags were stowed in a special container in the lower equipment bay. It typically took 45 minutes to defecate. The use of the bags did not obviate the associated odours, however.[20] Over their constant-wear garments the men wore two-piece teflon-fabric flight suits. With the crew in ‘shirt sleeves’ and the centre couch removed, the cabin appeared considerably larger. The decor was ‘battleship grey’. At an early stage a psychologist had recommended that, in order not to cause disorientation, there ought to be a two-colour scheme with brown below a certain horizontal level and blue above it, which sounded very reasonable until it was pointed out that in weightlessness there was no unique sense of ‘up’, and, by the psychologist’s own logic, if the colour scheme really did matter, then an inappropriate one would be upsetting! Aldrin, who had mastered weightlessness spacewalking on Gemini 12, found the freedom of movement in the command module enjoyable because, as he put it, he was spacewalking indoors! Fortunately, due to the care taken during their first few hours in space, none of the Apollo 11 crew developed any symptoms of ‘space sickness’.

EVA PREPARATIONS

The checklist for donning and checking the accoutrements required to venture out onto the surface was lengthy and excruciatingly detailed. First, each man unstowed his PLSS from its mount on the side wall and stood it on the floor by the forward hatch, then the bags containing the extravehicular gloves and helmet augmentation were retrieved and deposited on the floor next to the backpacks. Next, Armstrong retrieved the OPS packages from the stowage compartment on the side wall. In the event of the primary oxygen supply failing during the moonwalk, the OPS – which would be mounted on top of the PLSS backpack – contained sufficient oxygen to facilitate an emergency ingress and switch back to the cabin’s supply. Finally, he retrieved the remote control units containing status displays for the PLSS and radio system that were to be worn on the chest, and the light-blue deeply treaded rubber overshoes for firm traction outside in the weak lunar gravity. After Aldrin assisted Armstrong to put on his overshoes, Armstrong did so for Aldrin. Aldrin transferred his PLSS to the circular cover of the main engine of the ascent stage, added the OPS, then turned around and reversed up against the backpack. Armstrong helped him to fasten the waist and shoulder harnesses, which clipped to rings on the suit, attach the chest unit to the shoulder harnesses, and run the oxygen umbilicals from the PLSS to the sockets on the front of the suit. Aldrin then helped Armstrong to do likewise. The next step was to conduct a communications check with the portable radios. Aldrin disconnected his cabin communications umbilical and plugged in the one from his PLSS, and Armstrong did the same. As the backpacks projected 10 inches to the rear, they greatly reduced the scope for movement in the cramped cabin. On Earth the backpack weighed 120 pounds but on the Moon it was only 20 pounds. However, it retained its inertia and if it were to even nudge against the lightweight structures it would deliver a significant impact.

“Houston,” Collins called, “could you enable the S-Band relay at least one way from Eagle to Columbia, so that I can hear what’s going on?”

“There’s not much going on at the present time,’’ McCandless noted, “but I’ll see what I can do about the relay.’’

As part of the PLSS communications checks, the crew switched to VOX, and although this enabled people to listen in, the terse to and fro was not particularly illuminating for anyone without a checklist. McCandless participated only when addressed.

As 108 hours approached, Public Affairs Officer Jack Riley announced, “We do not at this time have a good estimate for the start of the EVA.’’ The astronauts were 30 minutes behind on the checklist, and slipping further. Jan Armstrong, on the floor in front of the television, laughed. “It’s taking them so long because Neil is trying to decide about the first words he’s going to say when he steps out on the Moon.’’ In the Collins home there was impatience rather than tension. Pat Collins sat with a plate of lasagne in the company of Clare Schweickart, Barbara Gordon and Mary Engle. Rusty Schweickart was attempting to follow the preparations by listening to the squawk box, but the astronauts’ commentary was not particularly informative. Noting that her husband had requested a one-way relay to enable him to listen in to transmissions between Eagle and Houston while on the near side of the Moon, Pat suspected that he would be on the far side when the moonwalk started, and therefore miss it. Joan Aldrin was relaxing, listening to Duke Ellington records. On breaking off, she said to Audrey Moon, “I’ve thought sometimes, privately, and may even have said so to Buzz, that he was so caught up in the mechanics of all this that he really hadn’t realised the significance of what he was doing; but now I really think he did!’’ She settled down to a plate of buffet nibbles and awaited developments.

Advancing through the preparations, Aldrin inserted the circuit breaker for the television system. “Houston, are you getting a signal on the television?’’ he asked. The MESA compartment was still in its stowed position, denying illumination to the camera inside, but the system was transmitting.

“The data we’re receiving looks good,’’ said McCandless, “and we’re getting synchronisation pulses and a black picture.’’

With the Sun low in the east, the 23-foot-tall vehicle was casting a very long shadow, and the ladder on the forward leg was facing westward. “You’ll find the area around the ladder is in a complete dark shadow,’’ Armstrong pointed out, “so we’re going to have a problem with the television, but I’m sure you’ll be able to see the lighted horizon.’’

“We request that you open the television circuit breaker,’’ McCandless called. “It’s been on about 15 minutes now, with the MESA closed.’’ Houston wanted it switched off to preclude the camera overheating in the insulated compartment. Aldrin was to have pulled the circuit breaker immediately following the test, but had missed a step on the checklist.

“Do we have a Go for cabin depress?’’ Armstrong asked.

When there was no response, Aldrin quipped about VOX letting Houston listen

A diagram of the Extravehicular Mobility Unit.

in, “They hear everything but that!” He made the call himself just in case there had been a fault with Armstrong’s radio. “Houston, this is Tranquility. We’re standing by for a Go for cabin depress.’’ Actually, the delay was because Charlesworth was polling his flight controllers. McCandless ought to have replied to Armstrong with a ‘Standby’.

“You’re Go for cabin depressurisation,’’ McCandless replied finally.

In fact, they were currently some 22 minutes behind their 108:00 estimate, and had just received permission to proceed with the final phase of the preparations; it would be another half hour before they would be ready to start the depressurisation of the cabin. With the moonwalk imminent, the Apollo 12 LM prime and backup crews of Pete Conrad, Al Bean, Dave Scott and Jim Irwin joined McCandless. Gene Kranz returned and sat with Charlesworth to watch the telecast on one of the wall screens.

Having configured the cabin for exposure to vacuum, Armstrong and Aldrin were able to finish suiting. Once the cooling system had been checked, the water umbilical was run from the PLSS to the suit to circulate water through the liquid coolant garment. The umbilical to the cabin’s oxygen system was removed, and the OPS umbilical was plugged into the vacant sockets. After he had applied an anti-fogging agent to the inside of Aldrin’s ‘bubble’ helmet, Armstrong slipped it over Aldrin’s head and locked it into position. He followed up with the polycarbonate shell incorporating the visor assembly that provided an inner and outer visor. The outer visor had a gold coating to reflect the harsh glare from the Sun which, in the absence of an atmosphere, was not only bright but also full-spectrum. Aldrin then repeated the procedure for Armstrong. Finally, they donned their extravehicular gloves, which had coverings of woven steel-fibre and rubberised finger tips for a modicum of dexterity. Taken together with the PLSS, OPS, helmet augmentation, extravehicular gloves and overshoes, the suit was described in NASA-ese as the extravehicular mobility unit. Aldrin wore a watch over the gauntlet-like sleeve of the right glove, but Armstrong decided to leave his watch inside as an emergency backup to the spacecraft’s event timer. A checklist for the external activities had been stitched onto the gauntlet of each left glove, listing that man’s specific tasks. Owing to uncertainty regarding the metabolic rate of an astronaut working on the lunar surface, and the fact that no one knew for certain how long the coolant water would last, the duration of the moonwalk had been set conservatively. However, the ‘clock’ on the life – support system started when the PLSSes were activated to pressurise the suits prior to depressurising the cabin.

‘‘Now comes the gymnastics,’’ Armstrong observed.

Aldrin carefully reached down and opened the valve built into the waist-high forward hatch, and then they monitored the pressure meter, which was initially at 4.8 psi. The depressurisation was slowed by the bacterial filter incorporated into the valve to protect the lunar environment from terrestrial biota, lest this be sampled, returned to Earth and misinterpreted as evidence of lunar life. As the pressure decreased, the rate of decrease slowed as it took time for the remaining gas molecules to find their way to the vent valve. ‘‘It sure takes a long time to get all the way down, doesn’t it?’’ mused Aldrin. When the pressure fell below 0.2 psi he tried the hatch, but it would not budge.

‘‘Neil, this is Houston. What’s your status on hatch opening?’’ McCandless called 10 minutes into the procedure.

‘‘Everything is Go here. We’re just waiting for the cabin to blow enough pressure to open the hatch. It’s about one-tenth on our gauge now,’’ Armstrong replied. Fifteen seconds later, he announced, ‘‘We’re going to try it.’’ But even at 0.1 psi, the 32-inch-square hatch would not open. Aldrin suggested that they also open the overhead valve, but they decided to wait. The cabin had vented sooner in altitude chamber tests, but as a chamber never establishes a perfect vacuum this had not given an accurate time measurement. As the hatch was only a thin metal cover of little rigidity, Aldrin carefully peeled back one of its corners to break its seal. Ice crystals formed as the residual air rushed out. Aldrin then readily hinged the hatch in towards his feet. “The hatch is coming open,” Armstrong announced.

“The valve’s in Auto,” Aldrin confirmed as he set the hatch valve to enable it to be operated from the outside.

The final task was to install the lunar equipment conveyor (LEC). This was a long nylon tether with a hook at each end to enable it to be linked into a loop and run around a pulley on a fixture located in the cabin. It had additional hooks on it to attach equipment for transfer to or from the surface. For Armstrong’s egress, the tether was hooked to the tie-down strap of his neck-ring as a safety precaution. With the hatch open wide, Armstrong faced aft and, with one hand leaning on the cover of the ascent engine, carefully lowered himself until he was kneeling on the floor with his feet in the hatch. Then Aldrin provided cues to help him to reverse out. With the bulky PLSS on his back it was a tight fit, but the hatch was already as large as the vehicle’s design could accommodate. Rusty Schweickart called to those in the Collins home that the hatch was finally open. Listening to Aldrin assisting Armstrong out, Schweickart remarked, “Don’t bump into anything! Just find the ladder, Neil!’’ When CBS anchorman Walter Cronkite wondered why Armstrong was taking so long, Schweickart muttered that it was “because he doesn’t have eyes in his rear end’’. Armstrong reversed out across the porch more or less flat on his stomach until his boots were at the far end, then he grasped the side rails and pushed himself up onto his knees. Aldrin pushed a bag of packaging through the hatch, and Armstrong dumped it over the side. By this point, they had been living off their PLSS resources for 25 minutes.

“Houston, I’m on the porch,’’ Armstrong announced.

Fifteen seconds later, Aldrin started the Maurer 16-millimetre camera that he had earlier installed on the bracket in the top-right corner of his window. Since he had no viewfinder, he adjusted it as best he could to view Eagle’s shadow, with a little of the illuminated lunar surface to each side. Armstrong entered the frame 30 seconds into the sequence.

“Stay where you are a minute, Neil,’’ called Aldrin. In preparation for his own egress, Aldrin partially closed the hatch to enable him to cross to the left-hand side of the cabin, and he did not want Armstrong to snag the tether on the hatch.

“Can you pull the door open a little more?’’ Armstrong prompted, when told he could continue.

“All right,’’ said Aldrin, and he opened the hatch fully, into the space where he had previously been standing.

As Armstrong prepared to descend the ladder, Columbia passed ‘over the hill’ and, deprived of his relay, Collins’s eagerness to hear what Armstrong would say as he stepped onto the lunar surface was frustrated.

In case Armstrong had forgotten to deploy the MESA, Aldrin asked, ‘‘Did you get the MESA out?’’

“I’m going to pull it now,” Armstrong replied. He located the D-ring alongside the porch using his left hand, and tugged it. The pallet on the front-right quadrant of the descent stage hinged down until just short of horizontal. “Houston, the MESA came down all right.’’

“Roger,” replied McCandless. “And we’re standing by for your TV.’’

“The television circuit breaker is in,’’ reported Aldrin. The transmission was by the high-gain antenna.

Apollo requirements

The objective of the Lunar Orbiter series was to reconnoitre possible landing sites for Apollo. As they had insufficient film to search for sites, they concentrated on sites that appeared suitable on the basis of telescopic observations. The Apollo Site Selection Board reduced an initial list of 30 candidates – all located on the near side of the Moon within 45 degrees of the meridian and 5 degrees of the equator – to a short-list of five by applying the following operational factors:

Of which more in chapter 10.

The primary objective of the Surveyor missions was to investigate the dark plains. Five Apollo Landing Sites (ALS) were selected in the equatorial zone for the early Apollo landings (bottom).

• Smoothness: Relatively few craters and boulders.

• Approach: No large hills, high cliffs, or deep craters that could result in incorrect altitude signals to the lunar module landing radar.

• Propellant requirements: Least potential expenditure of spacecraft propellants.

• Recycling: Effective launch preparation recycling if the countdown were to be delayed.

• Free return: Sites within reach of the spacecraft launched on a free-return translunar trajectory.

• Slope: Less than 2-degree slope in the approach path and landing area.

The flight dynamics team insisted that the primary site be located in the eastern hemisphere, in order to allow room further west for one or two suitably lit backup sites in the event of the launch being postponed by several days. As the launch ‘windows’ for a given site occurred only once per month, it was thought better to go for a secondary site several days late than to wait a month for the primary site to present itself again. The time of landing had to be just after local sunrise, as the Sun was required to be low on the horizon to cast sufficient shadows to reveal surface topography. Because the Sun traverses the lunar sky at a rate of 12 degrees per 24 hours, the backup sites were set 12, 24 or 36 degrees apart in lunar longitude to ensure that the illumination would be right for a delayed mission. On the other hand, the primary site could not be too far east, as this would not allow sufficient time after the final limb crossing to perform the navigational checks prior to initiating the powered descent. All sites had to be within 5 degrees of the lunar equator because a higher latitude would require a less propellant-efficient trajectory, and propellant economy was a priority for the first landing mission. Furthermore, the approaches to the sites had to be flat in order not to complicate the task of the landing radar. These operating constraints restricted the first landing to an eastern dark plain near the equator, which put the primary landing site in either the Sea of Tranquility or the Sea of Fertility, the backup site in the Meridian Bay, and the reserves in the Ocean of Storms. However, the Sea of Fertility was too far east to accommodate the final navigational update, which left the Sea of Tranquility, where there were two sites. The trajectory of Apollo 8 had been timed to inspect the easternmost site, ALS-1, called 2P-2 by the Lunar Orbiter team, at ideal illumination.

The time of the landing was determined by the location and the acceptable range of Sun elevation angles. The range of these angles ran from 6 to 14 degrees, east to west. Under these conditions, the visible shadows of craters would aid the crew in recognising topographical features. As the Sun angle approached the descent angle, the mean value of which was 16 degrees, the viewing conditions would be degraded by a ‘washout’ phenomenon in which backward reflectance was high enough to eliminate contrast. Sun angles above the flight path were not as desirable, because shadows would not be readily visible unless the Sun was significantly outside the descent plane. Because lunar sunlight incidence changed about 0.5 degree per hour, the Sun elevation angle restriction defined a 16-hour period, recurring every 29.5 days, when landing at a given site could be attempted. The number of Earth-launch opportunities for a given lunar month was equal to the number of candidate landing sites. The time of launch was primarily determined by the allowable variation in launch pad azimuth. A total launch pad azimuth variation of 34 degrees afforded a launch period of 4 hours 30 minutes. Two launch windows occurred each day. One was available for a translunar injection over the Pacific Ocean, and the other over the Atlantic Ocean. The injection opportunity over the Pacific Ocean was preferred because it usually permitted a daytime launch.

PASSIVE THERMAL CONTROL

The REFSMMAT for the translunar coast used the ecliptic, which is the plane in which Earth orbits the Sun: two of the three axes of the REFSMMAT were relative to the ecliptic, and the third was aligned along the Earth-Moon line at the time of TLI. To prevent one side of the spacecraft roasting and the opposite side freezing in the constant sunlight of cislunar space, it was to be oriented with its principal axis perpendicular to the ecliptic, then set rolling on a 20-minute cycle for passive thermal control (PTC) in a regime more popularly known as the barbecue mode. This had to be established before the astronauts could retire for the night. There were four options in the flight plan for midcourse corrections to refine the trajectory for lunar orbit insertion. The first was scheduled 9 hours after TLI, but since the delta-V was only 17 feet per second the burn was deleted, and the initiation of PTC advanced. Ten hours into the mission, after orienting the spacecraft perpendicular to the ecliptic, Collins gave the computer 20 minutes in which to fire the RCS thrusters as necessary to eliminate any axial wobble.

While waiting, Aldrin enquired about their altitude, which was 50,000 nautical miles. “It’s a beautiful sight,” he enthused, referring to Earth. “I can see snow on the mountains of California. It looks like LA doesn’t have much of a smog problem today. With the monocular, I can discern a definite green cast to the San Fernando Valley.’’

“How’s Baja California look, Buzz?’’ Duke asked.

“It has got some clouds up and down it, and there is a pretty good circulation system a couple of hundred miles off the west coast of California.’’

“Your rates look really great, now,’’ Duke called a few minutes later. “You can start your PTC.’’

“If you would like to delay PTC for 10 minutes or so, we can shoot you some television of a seven-eighths-phase Earth,’’ Armstrong offered.

Duke checked whether Goldstone was configured to receive television; it was. “It will be recorded at Goldstone and then replayed over here, Neil. Any time you want to turn her on, we’re ready.’’

“We’re sending a picture of Earth right now. Let us know if they’re receiving at Goldstone.’’

“Goldstone says it looks great,’’ Duke confirmed.

Armstrong was pointing the camera through the window beside his couch, and they had put up shades to prevent the Sun entering the other windows and causing internal reflections. He zoomed in until Earth filled the screen, and was pleased to observe that the automatic gain control adjusted the aperture to compensate.

“We’d like 10 minutes’ worth of television,’’ Duke requested. “And we’d like a narrative on the exterior shots. We also suggest you might try an interior position.’’

“We’re seeing the eastern Pacific Ocean,’’ replied Armstrong. “We’ve not been able to visually pick up the Hawaiian Island chain, but we can clearly see the western coast of North America – the United States, the San Joaquin Valley, the High Sierras, Baja California, and Mexico down as far as Acapulco and the Yucatan peninsula. And you can see on through Central America to the northern coast of

South America, Venezuela and Colombia. I’m not sure you’ll be able to see all that on your screen down there.’’

“Roger, Neil,’’ acknowledged Duke. “We wanted a narrative so that when we get the playback we can correlate what we’re seeing.’’

Although Armstrong and Aldrin had each remarked on the diminishing view of Earth, Collins had been too busy sighting on stars and operating the computer. “I haven’t seen anything but the DSKY so far,’’ he pointed out.

“It looks like they’re hogging the windows,’’ Duke consoled.

“You’re right,’’ Collins confirmed.

There was a distinct sense of distance – Earth and the Moon were both far off – but the distances were so immense that, in the absence of points of reference along the way, there was no sensation of movement despite the spacecraft’s high speed.

After 15 minutes, Duke announced, “You can terminate the television at your convenience, and then initiate PTC.’’ The impromptu telecast had verified that the television system was working beautifully.

Collins initiated the roll. With the Sun, Earth and Moon passing in procession by the windows, the illumination in the cabin became very dynamic.

As the camera was packed away, Armstrong gave a crew status report, reading their individual radiation monitors, noting that they had not taken any medications, and saying that in his opinion they were “fit as a fiddle’’, by which he meant they had not developed any symptoms of ‘space sickness’.

“As far as we can see,’’ Duke agreed, ‘‘you’re cleared for some zzzz’s.’’ In fact, as a result of having deleted midcourse correction 1, they were two hours ahead on the time line.

When testing the CSM with Apollo 7, Wally Schirra’s crew had maintained a staggered sleeping cycle in which there was always one man awake to monitor the spacecraft. On Apollo 8 Frank Borman’s crew had done the same, with the result that they slept poorly and were exhausted on entering lunar orbit. It was therefore decided that future crews should adopt a single sleep cycle. Armstrong was eager for his crew to conserve their energies in transit, to ensure that they would be alert on arrival in lunar orbit. In fact, it had been agreed that he and Aldrin would act as passengers because their mission would not start until they were in lunar orbit, and Collins would act as the chauffeur for the translunar coast. Although Duke signed off early, the crew did not retire until 10.30 pm on their Houston-time watches. Having arisen very early to prepare for launch, it had been a long day, and in their last few hours they were feeling distinctly drowsy. They had their supper, placed shades over the windows to block out the Sun and dimmed the internal lamps. Armstrong and Aldrin then disconnected their communications links and snuggled into enclosed hammocks – in effect mesh sleeping bags slung beneath the side couches – while Collins, the ‘watch keeper’, donned a lightweight headset with its earpiece on low volume, in case of a call from Mission Control, and strapped into the left-hand couch using a lap belt; as he rested, he realised that he no longer had any discomfort in his knee.

Cliff Charlesworth, Gene Kranz and Glynn Lunney were to rotate 8-hour shifts during the translunar coast. The ‘graveyard’ shift was handled by Lunney’s Black

Team. For the first 24 hours of a mission, flight controllers maintain a particularly close eye on the telemetry in order to identify the quirks of the new craft early on, and to establish norms and consumable rates.

Goldstone sent the taped telecast to Houston by a land line, where the signal was fed through conversion equipment for display on the wall screen and release to the media. On arriving home from the Cape and finding the press on her lawn, Jan Armstrong informed them that it had been a long day and she really needed to sleep, but happened to switch on her television as the networks started to run the telecast; the other wives missed it.

MOONWALK

On the flight plan, the moonwalk was scheduled to be made when the 210-foot – diameter dishes at Goldstone and the Parkes Observatory in New South Wales, Australia, would both have a clear line of sight in order to provide 100 per cent redundancy in these large antennas. However, advancing the schedule meant that the Parkes antenna, which could not dip all the way down to the horizon, could not receive until the Moon was well up; and in any case, wind gusts threatened to cut operations short. And since a problem at Goldstone was degrading the slow-scan television signal, the smaller 85-foot antenna at the Honeysuckle Creek Tracking Station 25 miles from Canberra, Australia, became the prime receiver for coverage of the egress. Built in 1967, Honeysuckle Creek had tracked previous missions but as Bernie Scrivener, the administrative officer, noted, “Somehow this seemed to be much more important; this was the day for which everyone on the station had worked and trained.’’ Australia’s Prime Minister, John Gorton, joined a large group of technicians to witness the event. At 11.15 am local time, the Moon rose and the signal was strong. The Westinghouse black-and-white camera provided 320 lines of resolution at a scan rate of 10 frames per second. As television technician Ed von Renouard reflected, “When I was sitting there in front of the scan converter waiting for a pattern on the input monitor, I was hardly aware of the rest of the world. I heard Buzz Aldrin say ‘Television circuit breaker in’.’’ The signal came in. “When the image first appeared, it was an indecipherable puzzle of stark blocks of black at the bottom and grey at the top, and was bisected by a bright diagonal streak. I realised that the sky should be at the top – and on the Moon the sky is black.’’ Several weeks earlier, NASA had noticed that when the MESA was opened the camera affixed to it would be oriented upside down, and a switch had been installed at each ground station to flip the picture, and when von Renouard threw the switch ‘‘all of a sudden it made sense’’.

As one of the 10-foot-by-10-foot Eidophor screens in Mission Control flickered to life, it prompted cheers in the viewing gallery. ‘‘We’re getting a picture on the TV,’’ McCandless announced.

‘‘You got a good picture, huh?’’ Aldrin asked.

‘‘There’s a great deal of contrast in it,’’ McCandless replied, ‘‘and currently it’s upside down on our monitor, but we can make out a fair amount of detail.’’ In fact, the initial feed to Houston was by a land line from Goldstone, where the technician waited 30 seconds before flipping the image upright. Unfortunately, the problem with the conversion system made the image extremely contrasty.

“Will you verify the aperture I ought to have on the camera?” Aldrin asked. He was referring to the Maurer.

“Stand by,” McCandless re­plied.

Since the MESA rotation had stopped short of 90 degrees, the television view depicted the hor­izon tilted slightly down to the right. Watched by a mesmerised audience, Armstrong carefully descended the nine-rung ladder.

“Neil, we can see you coming down the ladder now,” reported McCandless.

The specifications for the extravehicular suit had required it to protect against temperatures in the range -250°F to +310°F, the former representing deep shadow and the latter full sunlight plus heat radiated by the surface. Although the ladder was in shadow, Armstrong was able to hold onto it without ill effects. Indeed, as he would later recall, “At no time could I detect any temperature penetrating the insulated gloves as I touched things.” hacking an atmosphere, the lunar surface is exposed to micrometeoroid bombardment. The tough outer covering was judged sufficient to protect against microscopic motes impacting at cosmic speeds.

On touchdown, the narrow lower section of the strut was to act as a piston and slide into the wider main strut and, by virtue of crushing a honeycombed filler, absorb the shock of the vehicle falling the final few feet, but Eagle had landed so gently that there was no significant compression and the interval from the lowest rung on the ladder to the foot pad was at almost its maximum 3.5 feet – a fact that Armstrong discovered when he jumped backwards off the final rung and, sliding his hands down the rails to maintain his stability, landed with both feet within the 3- foot-diameter pad. He jumped back up onto the ladder to verify that ascent was feasible, then down again. Meanwhile, Aldrin opened the f-stop of the Maurer on his own initiative. Although this washed out the ground beyond the shadow, it much improved the view of Armstrong. Twenty seconds later, McCandless issued the recommended settings, “Buzz, f/2 and 1/160th second for shadow photography on the sequence camera.”

At this point the Network controller in the Mission Operations Control Room noticed that the video from Honeysuckle Creek, which was being transmitted by microwave to Sydney and then relayed by an Intelsat geostationary satellite over the Pacific Ocean, was clearer, and so he switched to this. Although NASA fed the Honeysuckle picture to the commercial television networks, it used Goldstone’s audio.

The first step

For Armstrong, being a test pilot, the significant achievement of the mission had been the act of landing on the Moon. But for the public, that was only the prelude to a man making an imprint of his boot on the lunar surface.

“I’m at the foot of the ladder,” Armstrong announced. Standing on the foot pad, holding the ladder with his right hand and bent forward slightly in order to balance his PLSS, he inspected the surface to the left of the pad, as he had done in training. Although he was deep in Eagle’s shadow, sunlight backscattered from the zero-phase angle illuminated the shadowed side of the vehicle, enabling him to see reasonably well. “The LM foot pads are only depressed in the surface about 1 or 2 inches, although the surface appears to be very, very fine grained; as you get close to it, it’s almost like a powder.’’ At home, his wife urged him to “be descriptive”. Joan Aldrin clapped her hands in delight, “I can’t believe this’’. In the Collins home, someone remarked in amazement, “This is science fiction!’’ Although the picture from the slow-scan camera was ‘ghostly’, it was remarkable (and, oddly, not envisaged by science fiction) that people on Earth were able to watch their representative take his first step onto the lunar surface ‘live’ on television. The Mission Operations Control Room was totally silent. In the News Center, journalists were watching on a theatre­sized Eidophor screen. Ironically, the town of Carnarvon, which hosted one of the tracking stations of the Manned Space Flight Network, had no television facilities. However, the Australian Broadcasting Corporation had arranged for the Overseas Telecommunications Commission to relay the moonwalk via satellite. In the local theatre the townspeople had installed a 14.5-inch set which people at the rear of the hall watched through binoculars!

Having described the strut and the adjacent surface, Armstrong announced, ‘‘I’m going to step off the LM now.’’ On the translunar coast, Aldrin had asked him if he had decided what he would say on stepping onto the surface, and he had said he was still thinking it over. Having rejected quotations from Shakespeare and the Bible, and things that he deemed to be pretentious, it dawned on him as he stood at the foot of the ladder that there was, in fact, only one thing to say! Holding onto the ladder with his right hand, he placed his left boot firmly on the surface alongside the pad. ‘‘That’s one small step for a man, one giant leap for Mankind.’’[33] [34]d The historic first words having been issued, the Mission Operations Control Room broke into hearty applause. Dave Scott, who flew on Gemini 8 with Armstrong, would later reflect that it was typical of the man to have deliberated for so long over what to say, and then expressed so much in so few words.

Armstrong released his grip on the handrail of the ladder and stepped fully off the foot pad. Walter Cronkite proudly told his CBS audience that a 38-year-old

American was now standing on the surface of the Moon. When Armstrong scraped his foot across the surface, he noticed that the dark powdery material coated his overshoe. “The surface is fine and powdery. I can kick it up loosely with my toe. It adheres in fine layers like powdered charcoal to the sole and sides of my boots.” Although his boots only slightly impressed the surface, the material preserved the imprint of his boots very well. “I only go in a small fraction of an inch – maybe one – eighth of an inch – but I can see the prints of my boots and the treads in the fine, sandy particles.”

Wearing the 180-pound extravehicular mobility unit, Armstrong’s mass was 340 pounds, but in the weak lunar gravity he weighed only one-sixth of this and was light on his feet. He did not feel the weight of the suit, since its internal pressure made it self-supporting. Holding the ladder with both hands, he did several knee-bends and then took a few steps away from the foot pad, briefly leaving the view of the television camera. Some members of the medical community had expressed concern that the astronauts would have difficulty in rapidly adapting to lunar gravity, and had urged that time be reserved for acclimatisation, with an immediate recall if this were to prove difficult. However, this ignored the fact that they would have been exposed to lunar gravity inside the LM for several hours prior to egressing, during which time they would be acclimatising – if, indeed, a period of acclimatisation should prove necessary. Others had expressed concern that if an astronaut were to fall onto his back he might have difficulty regaining an upright stance. If Armstrong had slipped early on, this may have prompted his immediate recall. He was determined to allay such concern. “There seems to be no difficulty in moving around as we suspected,’’ he continued. “It’s even perhaps easier than the simulations at one-sixth gravity. It is actually no trouble to walk around.’’

Having moved back in order to see beneath the vehicle, Armstrong said, “The descent engine didn’t leave a crater of any size. It has about 1 foot clearance off the ground. We’re essentially on a very level place here. I can see some evidence of rays emanating from the descent engine, but a very insignificant amount.’’ At this point, he unhooked the LEC from his suit, but kept hold of it. “Buzz, are we ready to bring down the camera?’’

“I’m ready,’’ replied Aldrin. “You’ll have to pay out all the LEC. It looks like it’s coming out nice and evenly.’’

After training had suggested that it would be difficult to carry the loaded rock boxes up the ladder at the end of the moonwalk, the LEC, dubbed the ‘Brooklyn clothes line’, had been devised. It had then been decided to use this to transfer out the Hasselblad camera. Armstrong was to use the LEC in hand-over-hand fashion to lower the equipment transfer bag. Now that he had stepped away from the LM, the illuminated terrain ruined his dark adaptation. ‘‘It’s quite dark here in the shadow, and a little hard for me to verify that I have good footing,’’ he pointed out. ‘‘I’ll work my way over towards the sunlight here, without looking directly into the Sun.’’ He did not want to enter full sunlight because he did not yet desire to lower his gold-coated visor. As he moved off to the southern edge of the shadow, Aldrin elevated the Maurer, and the western horizon appeared in the field of view. At this point, the movie camera exhausted the 8 minutes of film that had remained in the magazine with which Aldrin had set it running. At this point, too, having briefly switched the television feed back to Goldstone, then to Honeysuckle Creek and once again to Goldstone, Houston was informed that the 210-foot antenna at Parkes had finally acquired the signal and, since this had the best image quality to date, it was fed to commercial television networks for the remainder of the moonwalk.

The bodywork of the Hasselblad 500EL Data Camera was highly reflective for thermal control on the lunar surface, and it had an f/5.6 lens with a focal length of 60 millimetres. The shutter speed, aperture and focus were all manual; only the electric film-advance was automatic. The adjustments had been enlarged to enable them to be operated by gloved hands. The astronauts had memorised the exposure settings for different Sun angles. In order to facilitate precise measurements across a frame for ‘data extraction’, a glass plate bearing a grid of 25 crosses had been positioned immediately in front of the focal plane. It was originally intended that the camera would be operated hand-held, but during training Armstrong had suggested that a bracket be added to the chest pack in order to make the camera hands-free. Because the helmet would prevent use of the top-mounted view finder, the rotating mirror and viewing plate had been deleted, and the astronauts had learned to aim by trial and error. They had two cameras, but only one had the modifications for external use.

After removing the Hasselblad from the equipment transfer bag, Armstrong mounted it on his bracket. He draped the LEC beside the forward leg. Noticing that the Maurer had stopped, Aldrin attended to it. In addition to exchanging the film magazine, he moved the camera to a bracket on a bar running horizontally across his window, set the exposure for the illuminated terrain, and pointed it northwest in order to document the locus of most of the external activities. As Armstrong set out to snap pictures for a partial panorama of the site, McCandless prompted him to take the contingency sample. This had priority on the checklist for the early part of the excursion because, if a suit or PLSS problem were to oblige him to retreat before he could fill the rock boxes, or if it should prove impossible to transfer the boxes to the cabin, they might have to return to Earth with only this small sample. Armstrong said that he would collect the sample when he had taken his pictures. He shot nine frames, turning slightly each time to document the horizon running from due south, through west and around to due north. This done, he moved north about 12 feet, stepping out of Eagle’s shadow into sunlight to enable him to see the ground as he took the sample, knowing that this position would be within the field of view of the Maurer. As he still had not lowered his gold-plated visor, he stood with his back to the Sun, drew a scoop from the pocket strapped onto his left thigh, and straightened the multi-segmented handle just as Aldrin restarted the Maurer. As Armstrong scraped the scoop across the surface, he discovered that although the surficial material was loose, it consolidated with depth and prevented the scoop from penetrating more than a few inches. Nevertheless, by dragging the tool across the ground several times he was able to fill the bag.

‘‘It looks beautiful from here, Neil,’’ Aldrin called, referring to the sampling.

Armstrong, presuming Aldrin’s remark to be a comment on the moonscape, replied, “It has a stark beauty all its own. It’s like much of the high desert of the United States. It’s different, but it’s very pretty out here.’’ Then to Houston he said, “Be advised that a lot of rocks have what appear to be vesicles in their surfaces.[35] Also, I’m looking at one now that appears to have some sort of phenocrysts in it.’’[36] After detaching the transparent sample bag from the scoop he inserted the handle several inches into the ground. On inspecting the contents of the bag, he noted that although the surface generally appeared shades of tan, the sample was black. After sealing the bag, he kneaded it with his fingers, observing that although most of the material was very finely grained there were also fragments of rock. His next task was to put the bag into his thigh pocket, but the peripheral vision through the visor was so limited that he could not see the flap. “Is the pocket open, Buzz?’’

“Yes, it is. It’s not up against your suit though. Hit it back once more. More towards the inside. Okay. That’s good.’’

“Is that in the pocket?’’

“Yes. Push it down. It’s not all the way in. Push it. There you go.’’

“The contingency sample is in the pocket,’’ Armstrong informed Houston, to the relief of the scientists. In fact, they would have preferred the sample taken well away from Eagle because the exhaust plume had disturbed the fine material in the immediate vicinity and potentially contaminated that which remained. In addition, the oxidiser pressure had been relieved soon after landing by venting, and some of the nitrogen tetroxide might have coated the surface. But Armstrong had been told to remain close to the vehicle.

Second man out

After Armstrong had been on the lunar surface for about 15 minutes, Aldrin asked, “Are you ready for me to come out?’’

“Just stand by a second. I’ll move this over the handrail,’’ replied Armstrong. He adjusted the position of the LEC on the strut to ensure that it would not hinder Aldrin’s egress, and then he stood to the southwest in order to document Aldrin’s egress. When Fred Haise alerted Joan to her husband’s imminent appearance, she, as a former actress, observed, “It’s like making an entrance on stage.’’

Before Aldrin left, he gave the Maurer camera a final inspection. On 27 February 1969 Maxime A. Faget, Director of Engineering and Development at the Manned Spacecraft Center, wrote to Owen E. Maynard, chief of the mission operations branch. Knowing that the television coverage of the moonwalk would not be of very high quality, Faget had had high hopes for the film record. But discovering what was intended, he was dismayed. “From the stand point of public information and historical documentation,” he wrote, “I am terribly disappointed to find that although 560 feet of movie film has been set aside for lunar surface use, none will be exposed with the intent of providing a first-class visual appreciation of the astronauts’ activity on the Moon during this singularly historical event. The impression of this occasion will be marred and distorted by the fact that the greatest frame rate [in automatic mode] is 12 frames per second. One can argue that ‘suitable’ (although jerky) motion rendition is produced by double-framing. Nevertheless, it is almost unbelievable that the culmination of a $20 billion program is to be recorded in such a stingy manner.’’ The situation was actually worse than Faget had been led to believe, since with the camera running at its slowest rate of 1 frame per second a 140-foot reel of thin base film was sufficient for only 93 minutes, and because there would be no one available to replace the magazine it would not be possible to document the entire moonwalk.

‘‘All set,’’ called Armstrong. ‘‘You saw what difficulties I was having. I will try to watch your PLSS from here.’’ As Aldrin’s feet appeared in the hatch, Armstrong gave cues to assist him to reverse out along the porch.

Aldrin, ‘‘making sure not to lock it on my way out’’, partially closed the hatch in order to protect the cabin from the harsh thermal environment.

‘‘A pretty good thought,’’ chuckled Armstrong.

‘‘That’s our home for the next couple of hours, and we want to take good care of it,’’ Aldrin added. ‘‘Okay. I’m on the top step.’’ As he started down the ladder he provided commentary because one of his assignments was to evaluate the ability of a man to operate in the lunar environment, ‘‘It’s a very simple matter to hop down from one step to the next.’’ As her husband appeared on the television, Joan screamed with delight, rolled on her back and kicked her legs in the air, then sat up again and blew kisses.

‘‘You’ve got three more steps and then a long one,’’ Armstrong advised.

Aldrin continued his commentary as he prepared to jump down on to the foot pad, ‘‘I’m going to leave that one foot up there, and both hands down to about the fourth rung up.’’

‘‘There you go,’’ said Armstrong as Aldrin jumped.

Following Armstrong’s lead, Aldrin tested jumping back up, but in this case his boot fell short of the lowest rung and dropped down again.

‘‘About another inch,’’ Armstrong noted.

Aldrin jumped up again, this time successfully. It was a matter of recalibrating his muscles for one-sixth gravity. ‘‘That’s a good step,’’ he noted wryly.

‘‘About a 3-footer,’’ said Armstrong.

‘‘Beautiful view!’’ said Aldrin, as he looked left and right while standing on the foot pad.

‘‘Isn’t that something!’’ Armstrong agreed. ‘‘It’s a magnificent sight out here.’’

Impressed by the contrast between the stark shadows and the barrenness of the illuminated surface, Aldrin said, ‘‘Magnificent desolation.’’ Retaining hold of the ladder with both hands, he stepped backwards off the pad, then let go with his left hand and turned to face north. He was struck by the Moon’s small size. To a man

Buzz Aldrin descends the ladder.

standing on the surface, the horizon was less than 2 miles away, making it very evident that he was on a sphere with the surface falling away in all directions. This had not been so evident when looking out of the window since, being higher, with the horizon further away, he had been able to see to a ‘reasonable’ distance. Standing freely, he noted that it was necessary to lean forward about 10 degrees to balance the mass of his backpack. However, this stance assisted in looking down, and he remarked that although the surface was finely grained and there were some rocks, there were some other objects that looked like clods of dirt. The loose material was different from terrestrial soil which, in addition to fragments of rock, contains the products of chemical weathering and organic humus – the lunar material is best described as a ‘regolith’, this being the term for material composed solely of rock fragments with a seriate distribution of sizes. Since a breccia is a consolidation of rock fragments bound in a matrix of finer material, geologists would subsequently introduce the term ‘regolith breccias’ for the compacted clods of regolith which, although they looked like rocks, readily fell apart when disturbed.

‘‘This pad sure didn’t penetrate far,’’ Aldrin observed.

‘‘No. It didn’t,’’ Armstrong agreed.

As had Armstrong, Aldrin stepped back and peered beneath Eagle, ‘‘There’s absolutely no crater there at all from the engine.’’ Although the plume had blown the dust out radially, it had not excavated the surface. However, there was a mark directly beneath the engine where the probe of the left landing gear had struck the surface.

Armstrong had also observed that whereas the probe on the left leg was bent beneath the vehicle, that on the right leg was bent outward. ‘‘I think that’s a good representation of our sideward velocity at touchdown.’’

As per his checklist, Aldrin continued to familiarise himself, but since he had not set the voice-actuated keying control for his downlink at its maximum setting he was cutting out; at times, much of what he said was rendered unintelligible.

Meanwhile, Armstrong had tilted the MESA down past horizontal and pulled a lanyard to remove the thermal insulation blanket to expose the stowed apparatus. ‘‘Houston, I have the insulation off the MESA now, and the MESA seems to be in good shape.’’ Turning his attention to the television camera, he announced, ‘‘I’m going to change lenses on you.’’ As installed, the camera had a lens that provided an 80-degree field of view. He retrieved one with a 35-degree field of view from a slot of the MESA and put it on the camera, stowing the original lens. ‘‘Tell me if you’re getting a new picture.’’

‘‘That’s affirmative,” replied McCandless. ‘‘We’re getting a new picture. You can tell it’s a longer-focal-length lens. And for your information, all LM systems are Go.’’

‘‘We appreciate that,’’ Aldrin replied. ‘‘Thank you.’’

The commemorative plaque

Although each man had his individual checklist sewn onto the gauntlet of his left glove, several items were not listed. The unveiling of the commemorative plaque on the forward strut was such a late addition to the training that only Armstrong was

The design of the commemorative plaque on Eagle’s forward leg, and a television view of its unveiling by Neil Armstrong (right of frame) and Buzz Aldrin.

familiar with it. With both men standing alongside the ladder, in view of the television camera, he described the plaque, “First, there’s two hemispheres, one showing each of the two hemispheres of the Earth. Underneath it says ‘Here men from the planet Earth first set foot upon the Moon, July 1969 AD. We came in peace for all mankind’. It has the crew members’ signatures and the signature of the President of the United States.’’ Measuring 9 by 7.625 inches with a thickness of 0.006 inch, it was made of #304 stainless steel with a brushed finish. The map and signatures were black epoxy in etched inscriptions. It was curved, conformal with the 4-inch radius of the strut but not actually in contact with it, being instead attached to the ladder by four spring clips, two on the third rung and two on the fourth rung. Armstrong hinged out and unlatched the sheet of stainless steel that had protected the plaque, in order to leave it exposed.

According to NASA Administrator Thomas O. Paine, the decision to make the plaque was a last-minute affair in which he and Wallis H. Shapley, an Associate Deputy Administrator, sketched the design, called in an artist to draw it properly, and sent the result to the White House for approval. However, Paine’s account is contradicted by Jack A. Kinzler, an engineer at the Manned Spacecraft Center. This account stated that when Robert R. Gilruth phoned seeking ideas for how to celebrate the landing, Kinzler suggested a plaque to be left on the descent stage. Kinzler and colleague David L. McCraw produced a prototype that featured a US flag of red, white and blue paints baked into the etched figure in stainless steel, together with the signatures of the crew and the name of the landing site – on the assumption this would be named. Gilruth replaced the flag by two hemispheres with continental outlines devoid of national boundaries, to identify the planet of origin. Kinzler said that, ‘‘Once the plaque concept was approved, NASA headquarters took it over.’’ When it was sent to the White House, Nixon changed the wording to past tense, and asked that his signature be added. Julian Scheer, head of the Public Affairs Office, has added a twist to the story, saying that NASA refused a suggestion by Nixon that ‘under God’ be inserted after the word ‘peace’.[37] The plaque’s design was made public shortly prior to launch. The astronauts had not been involved in the project, but felt it was tastefully done.

‘‘Are you ready for the camera?’’ Armstrong asked.

Although Aldrin was scheduled to use the Hasselblad soon, he decided not to take it yet, ‘‘No. I’ll get it later.’’ He was closely following the checklist, and the next item was to relocate the television camera, ‘‘You take the television on out.’’

Having pulled a strap on the MESA to release the tripod on which he was to mount the television camera, Armstrong prompted, ‘‘Would you pull out some of my cable for me, Buzz?’’

‘‘How is the temperature on there?’’ Aldrin asked, as he drew the cable from a dispenser on the MESA. A temperature-sensitive patch on the television camera was designed to darken with increasing temperature; it was still white, indicating that the camera had not overheated while being tested prior to the deployment of the MESA.

‘‘The temperature of the camera is showing ‘cold’,’’ Armstrong reported. He transferred the camera from the MESA to the tripod, and set off with it northwest, dragging the cable out as he went. On the way, something shiny on the bottom of a small crater attracted his attention. It was later concluded that this was a piece of glass, formed by the heat of a high-speed impact melting the regolith. In fact, there are two types of crater, ‘primary’ and ‘secondary’, with the primary produced by the impact of an object from space at cosmic velocity, and the secondary by the fall of ejecta issued by another impact. Since ejecta expelled faster than about 1.5 miles per second will escape the Moon, the speed of a secondary impact is necessarily at least an order of magnitude lower than that of a primary, and because kinetic energy is proportional to the square of the velocity, the energy of a primary strike for a specific mass greatly exceeds that of a secondary, and is sufficient to melt and fuse regolith.

Seeing Armstrong pause, Aldrin pointed out that there was more of the cable in the dispenser. ‘‘No, keep going. We’ve got a lot more, although it’s getting a little harder to pull out.’’

‘‘How far would you say I am, Buzz?’’

‘‘Oh, 40, 50 feet.’’ Then Aldrin suggested that Armstrong give the audience a panoramic view. ‘‘Why don’t you turn around and let them get a view from there, and see what the field of view looks like?’’

‘‘Okay,’’ Armstrong agreed.

‘‘You’re backing into the cable,’’ Aldrin warned, on seeing that Armstrong was at risk of entangling his feet in the cable. ‘‘Turn around to your right; that would be better.’’

‘‘I don’t want to go into the Sun if I can avoid it,’’ Armstrong pointed out. Now that he was in full sunlight, he was taking care not to point the camera towards the Sun because flooding it with harsh sunlight would undoubtedly damage it.[38] He set the tripod down 55 feet northwest of Eagle. “I’ll just leave it sitting like that, and walk around it.’’ Once in position, he inspected the lines inscribed on the top of the camera body to indicate the angular field of view of the lens. “Houston. How’s that field of view?’’

“We’d like you to aim it a little bit more to the right,’’ McCandless instructed. Armstrong adjusted the camera. “A little bit too much to the right! Can you bring it back left about 5 degrees?’’

“Do you think I ought to be farther away, or closer?’’ Armstrong asked once it was lined up on Eagle, showing Aldrin, who, having advanced to the next item on his checklist, was configuring the MESA for sampling activities.

“You can’t get much further away,’’ Aldrin pointed out, having pulled out all the cable.

Television panorama

Armstrong now set about moving/aiming the camera to give the audience a series of views around the horizon. The image became a blur while the camera was in motion, and cleared when he set it down. “That’s the first picture in the panorama,’’ Armstrong announced. “It’s taken just about north-northeast. Tell me if you’ve got a picture, Houston.’’

“We’ve got a beautiful picture, Neil,’’ McCandless confirmed.

He moved the camera further around the horizon. “Okay. Here’s another good one.’’ The horizon was featureless, but there was a lot of detail in the foreground. “Now this one is right down-Sun, due west, and I want to know if you can see an angular rock in the foreground sticking up out of the soil.’’

“We see a large angular rock in the foreground,’’ McCandless confirmed, “and it looks like there is a much smaller rock a couple of inches to the left of it.’’

“And about 10 feet beyond that is an even larger rock that’s very rounded,’’ said Armstrong. “The closest rock is sticking out of the soil about 1 foot; it’s about 18 inches long and about 6 inches thick, but is standing on edge.’’ Armstrong was spending a lot of time on this panorama because he believed on this first landing the geologists would welcome a view of the site.

“We’ve got this view, Neil,’’ McCandless prompted.

Armstrong moved the camera again, “This is straight south.’’

“Roger,’’ McCandless replied. “And we see the shadow of the LM.’’

“The little hill just beyond the shadow of the LM is a pair of elongate craters.’’ There were two craters aligned in an east to west direction to the southwest of the vehicle. “Probably the pair together is about 40 feet long and 20 feet across, and they’re probably 6 feet deep. We’ll probably get some more work in there later.’’ Armstrong returned the camera to face Eagle, where Aldrin was still working at the MESA. He had attached to the edge of the MESA the teflon bag in which they were to place samples prior to stowing them in a rock box, and had raised a table on which a box was to be mounted for access; in their stowed positions the boxes were recessed into the MESA pallet. After some adjustments to the pointing, Armstrong left the television camera viewing Eagle and the area immediately to its front. There was an 8-foot-diameter deployable S-Band dish with its own tripod stowed in a compartment in the front-left quadrant of the descent stage, but since erecting this would take 20 minutes this was to be done only if Houston deemed the quality of the transmission using the smaller dish of Eagle’s high-gain antenna to be unsatisfactory, which was not the case.

Having unstowed the Solar Wind Collector (SWC) from the MESA, Aldrin moved out to deploy it a short distance due north of Eagle. The experiment was a sheet of exceptionally clean aluminium on a staff that was to be positioned facing the Sun to soak up solar wind particles, particularly ions of helium, neon and argon (all of which were unreactive ‘noble’ elements in the Periodic Table). After Aldrin had extended the aluminium staff, he pulled out and locked the roller at the top, then drew down the 140-centimetre-tall and 30-centimetre-wide sheet from the roller and hooked it to a catch at the lower end of the staff.8 He found it difficult to drive the staff into the ground because (as had been noted by Armstrong while collecting the contingency sample) the finely grained surface material became consolidated at a depth of 4 or 5 inches. The sheet was to be rolled up at the end of the moonwalk and returned to Earth. Because it was to be analysed by a laboratory in Switzerland, the experiment was also known as the ‘Swiss flag’. On his way back from the television camera, Armstrong took several Hasselblad pictures of Aldrin with the experiment.

Aldrin observed that although the imprints left by their boot were generally only a fraction of an inch deep, their boots penetrated several inches where the loose material was piled up on the rims of small craters, and he wondered whether there was a correlation between the loose consistency and the change of slope. He had also noticed that when the toe of his boot penetrated the loose material at a shallow angle, it tended to displace a ‘slab’ of material as if it were solid, which, of course, it was not. A similar effect had been observed while pushing the surface material using the robotic arm of a Surveyor lander. Armstrong added an observation of his own, ‘‘I noticed in the soft spots where we leave foot prints nearly 1 inch deep, the soil is very cohesive, and will retain a slope of probably 70 degrees along the side of the foot prints.’’ These were welcome ‘soil mechanics’ observations.

FLIGHT DIRECTORS

Clifford E. Charlesworth was appointed as lead flight director for Apollo 11. Cool headed with an easy smile, he had been nicknamed the Mississippi Gambler by the flight controllers on account of the fact that, although he always appeared relaxed, he was focused and confident. As planning firmed up in early 1969, he shared the principal tasks among the available flight directors. Of the eight major phases of the mission, five had either been demonstrated by Apollo 8 or soon were to be by Apollo 10, and the three unrehearsed phases were the powered descent to the lunar surface, the moonwalk, and the lunar liftoff. As, by Apollo 11, Charlesworth would be most familiar with the Saturn V, he took launch on through to the translunar injection manoeuvre, plus the subsequent surface excursion. Eugene F. Kranz had most experience with the LM, including its unmanned test on Apollo 5 and manned test on Apollo 9, and was therefore assigned the lunar landing and transearth injection manoeuvre. As Glynn S. Lunney would have been to the Moon twice, both times focusing on the CSM, he was given responsibility for the lunar liftoff and rendezvous. Gerald D. Griffin and Milton L. Windler were assigned to other miscellaneous tasks. The flight directors met the branch chiefs of the flight control division to create their teams of flight controllers, balancing their individual areas of expertise to each phase of the mission.