Moonshot: The Inside Story of Mankind's Greatest Adventure - Dan Parry (2009)

Chapter 8. A TISSUE-PAPER SPACECRAFT

While inspecting the lunar module during the third day of the flight, Buzz picked his way carefully about the cramped cabin. Plumbing and bundles of wiring lay exposed on the floor, and in places the walls were no thicker than a couple of layers of aluminium. Fragile as it was, the LM remains unique in being the world's only manned spacecraft capable of a powered landing, whether on the Moon or anywhere else.1 The Mercury capsule, the Gemini spacecraft, even the Apollo command module were designed simply to fall into water, slowed only by parachutes. The Russians also used parachutes, although their spacecraft came down over land. In touching down on the Moon, which does not have an atmosphere, parachutes would be useless. If the LM were to survive unscathed, a gentle, powered descent was critical.

As he went about his work, Buzz continued to report on what he was doing for the benefit of CapCom Charlie Duke and those watching on television.

Aldrin: 'Like old home week, Charlie, to get back in the LM again.'

Mission Control: 'Roger. Must be some experience. Is Collins going to go in and look around?'

Armstrong: 'We're willing to let him go but he hasn't come up with the price of the ticket yet.'

Mission Control: 'Roger. I'd advise him to keep his hands off the switches.'

Collins: 'If I can get him to keep his hands off my DSKY, it'd be a fair swap.'

The TV broadcast, which NASA regarded as the clearest yet sent from space, lasted a little over an hour and a half.2 During that time Apollo 11 coasted more than 3,000 miles.

Once Buzz returned to the command module, the hatch was closed and the LM was sealed shut once again. The crew then completed a round of their routine chores before sitting down to dinner, accompanied by music. Both Armstrong and Collins had taken selections on cassettes which they listened to on a portable tape recorder; Buzz had decided he would be content with whatever they chose.

Once the spacecraft had been put into a PTC roll, Aldrin looked out at the heavens rotating slowly past the windows. Suddenly, there out in space was an object that was reflecting light and which almost appeared to be shadowing them. After Buzz pointed it out to Neil and Michael the three of them gathered at the windows, each waiting for the object to swing into view as the spacecraft gently rolled on its axis. Buzz got down into the lower equipment bay and took a closer look through the sextant and telescope, but all he could say for certain was that the object sometimes appeared to be L-shaped. As flying objects go it was definitely unidentified. In Buzz's words, they 'sure as hell were not going to talk about it to the ground' for fear of the curiosity and even concern it would raise. Someone might even suggest that the mission should be cancelled since aliens were apparently going along for the ride. 'We didn't want to do anything that gave the UFO nuts any ammunition,' Aldrin later said.3

The crew had already bid goodnight to Houston, but after thinking over his choice of words, Neil contacted Mission Control.

Armstrong: 'Houston, Apollo 11.'

Mission Control: 'Go ahead, 11. Over.'

Armstrong: 'Do you have any idea where the S-IVB [third stage] is with respect to us?'

Mission Control: 'Stand by.'

Mission Control: 'Apollo 11, Houston. The S-IVB is about 6,000 nautical miles from you now. Over.'

Armstrong: 'OK. Thank you.'

With the third stage eliminated, the men began to discuss other possible explanations. Sometimes the mysterious object looked like a hollow cylinder, at other times it resembled two connected rings. 'It certainly seemed to be within our vicinity and of a very sizeable dimension,' Buzz later remembered.4

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When Buzz approached George Low in March, seeking an answer to the 'first out of the hatch' question, Aldrin insisted it would be in the best interest of 'morale and training' if the decision were made quickly.5Buzz asked whether Neil's civilian status gave him an advantage, but Low told him it was irrelevant.6

Buzz was right in arguing that the matter needed to be settled soon, since Aldrin and Armstrong had to begin training for the EVA. For the moment they continued to work with the lunar module. Both had served on the backup crew for Apollo 8 and were already familiar with the LM. But the spacecraft's operational performance was largely untested and there was still much to learn. As part of their training, Armstrong and Aldrin occasionally visited Grumman's plant at Bethpage on Long Island, New York, to monitor the development of LM-5, the lunar module they would fly to the Moon.

After winning the $388 million contract to build a lunar lander in November 1962, Grumman quickly came up against a range of formidable problems. Immersed in a multitude of competing demands, the LM was to become one of the most challenging components of the entire Apollo programme. The painstaking search for solutions was led by Tom Kelly, a likeable engineer from New York. Supported by a team of 100 technicians, Kelly had been working on ideas for a lander even before Kennedy had laid down his challenge in 1961. Early on, he realised the vehicle would need to be small and light yet rugged enough to withstand the launch into Earth orbit and the three-day journey through space.

Kelly's work was to be overseen by the Apollo Spacecraft Program Office in Houston. Already the head of the Apollo office, Charles Frick, was embroiled in difficulties over the command module with his counterpart at North American Aviation. When he saw them 'screaming and cursing at each other' Chris Kraft could barely believe it.7 Kraft had heard the relationship was troubled but after shifting his attention from Gemini to the lunar missions, he saw for himself that 'bad vibes from Apollo were everywhere'.8 Kraft found that lessons learned during Gemini were being ignored both inside NASA and beyond. He believed the Apollo office had begun to adopt a stubborn sense of independence, and worse, this was filtering down to North American. Soon he began to suspect Grumman was slipping in the same direction.

The lander would be carried into space by the powerful Saturn V rocket, which could lift a 125-ton payload into Earth orbit. But this distance was less than 1 per cent of Apollo 11's journey to the Moon. After carrying the spacecraft into orbit, the booster's final stage would then re-ignite for the relatively short TLI burn. There was only so much fuel the third stage could carry and during TLI this would be quickly spent. Yet within this small amount of time the stage would have to push the fully laden spacecraft fast enough to send it all the way to the Moon. These limitations meant that at launch the rocket's payload – the spacecraft at the top of the stack – could not weigh more than 50 tons. The sturdy command module, robust enough to survive re-entry, weighed more than six tons, the service module behind it weighed almost 26, and the lunar module would have to carry at least 12 tons of fuel for its round trip to the surface. After equipment, consumables for the crew and scientific experiments had been taken into account, Kelly was told that the lander itself could not weigh more than four tons. The restriction was marginally increased during the spacecraft's development, but from the start the entire project was characterised by a perpetual struggle to save weight. The Saturn's constraints had an impact on almost every element of the LM's design. Failure to accept them would end any hope of a lunar landing before Apollo 11 even left Earth.9

Despite its lightweight structure, the spacecraft would have to be strong enough to survive a rough landing on uneven and dusty ground. Its critical systems would have to cope with a hostile environment beyond all hope of assistance, and it would have to be able to successfully launch from the lunar surface on its first attempt. When Apollo 11 lifted off from Cape Kennedy, 463 people sitting nearby guided the launch process and thousands of specialists were ready to resolve any last-minute problems. When the lander launched from the Moon, its two-man crew would be on their own.

In developing what Grumman initially called the lunar excursion module (LEM), Kelly's team proposed a two-stage spacecraft. The bottom half, the descent stage, contained the descent engine and associated fuel tanks. Delivering 10,000lb of thrust, the descent engine was the first large rocket motor that could be throttled up or down. This meant that the spacecraft could be flown at a decreasing speed as it slowly approached the surface. The descent would be partially controlled by a computer, allowing maximum fuel efficiency – which was critical since the LEM was carrying the slimmest margin of propellants. Only in the final stage of the descent would the spacecraft be flown manually.

Most of the top half of the vehicle, the ascent stage, was taken up by the cockpit, though it too had an engine. After the EVA, the astronauts would return to the cabin and when ready they would ignite four explosive bolts that would sever umbilical cables connecting the two sections of the spacecraft. They would then fire the ascent engine. The ascent stage would blast off from the Moon, and on returning to lunar orbit the crew would search for the command module, as envisaged in the original proposal for lunar orbit rendezvous. Armstrong and Aldrin would then rejoin Collins for the journey home.

In an emergency on the way down to the Moon, the crew could jettison the descent stage and use the ascent engine to quickly climb back up into space. Since emergencies in a lightweight spacecraft flying close to the rocky surface of the Moon could potentially be disastrous, the two engines needed to be as reliable as possible. Both were hypergolic, in that each used two types of propellant which ignited simply when allowed to mix. Neither relied on complicated moving parts such as pumps or igniters, therefore they were less likely to go wrong than traditional types of engine. The LEM's 16 thrusters, arranged in four groups of four around the ascent stage, also used hypergolic propellants.

Kelly's team originally put seats in the spacecraft, in common with almost every other flying machine. The crew were to look out of four large windows that were made of extremely thick glass and embedded in a heavy supporting structure.10 But this design came to be regarded as too heavy and two smaller triangular windows were fitted instead. These made it harder to see from the seats so bar-stools and metal cage-like structures were considered, until 1964, when two Houston engineers suggested Kelly would save further weight by removing the seats altogether. Standing during the short flight, the astronauts would be closer to the window than if they were seated, giving them a better view. 'Trolley-car configuration' astronaut Pete Conrad called it, thinking of a driver standing at his wheel. The crew would be held in place by Velcro strips securing their feet to the floor and by cables attached at the waist that were held under tension by a system of pulleys.

Now that the astronauts would be standing, the floor-space could be reduced until it was just three and a half feet deep. Looking towards the back wall, the space behind the crew positions was largely taken up by equipment casings that protruded into the cockpit. A unit on the left contained the environmental control system, while the floor in the middle of this area was raised to knee height to accommodate the ascent engine. Squeezed into the tiny ceiling above lay the hatch leading up into the command module. Despite the technological breakthroughs in the LEM's design, there was no escaping the thought that man was going to the Moon in a cabin the size of a broom cupboard. It was even equipped with a small vacuum cleaner to deal with the lunar dust.

For many months the spacecraft's torturous development process was delayed by problems, including engine instability, battery faults and leaks from lightweight pipes – and all the while the weight kept creeping up. In 1965, Houston asked for the limit of the LEM's load to be marginally raised. Headquarters consented, but Kelly knew much still needed to be done to keep within the restrictions. Grumman launched 'Operation Scrape' in an attempt to shave as much material from the structure as possible. This was followed by the Super Weight Improvement Program, implemented by a crack team of weight-saving experts personally led by Kelly. 'At one time we were paying about $10,000 an ounce to take weight off,' astronaut Jim McDivitt later recalled. Among other things, these campaigns led to a decision to scrap the panels protecting the vehicle from the Sun's heat and replace them with Kapton. Specifically developed for the LEM, Kapton – a golden, plastic foil – became one of its characteristic features. Crinkled by hand in order to reduce the transmission of heat, the foil was visible only on the descent stage since the upper half of the spacecraft was cloaked in a layer of aluminium plates, designed to dissipate the impact of micrometeoroids. The cockpit was pressurised, but as an added layer of protection during the descent the crew would wear pressure-suits.

Challenging as Kelly's work was, the complicated, occasionally delicate relationship with NASA made things harder still. In Houston, Frick had been replaced by Joe Shea, but old attitudes lingered on. The Apollo office and Grumman were failing to see eye to eye over a multitude of issues, and trust and understanding were beginning to fray at the edges. Chris Kraft later wrote that both Grumman and North American were failing to give technical information and diagrams to astronauts and flight controllers. He also believed the contractors were ignoring their obligation to attend meetings focusing on mission control procedures. Kraft's problems were compounded by internal wrangling within the Manned Spacecraft Center, yet throughout the bickering Kelly had to stay focused on the matter in hand.11

The lander needed to be capable of more than simply transporting men to the Moon. After reaching the surface, it would have to shelter its crew from a hostile environment and provide them with somewhere to eat, sleep and prepare for an EVA. The batteries, the environmental control and waste management systems, the oxygen and water supplies and the radio-transmitters all had to perform to high minimum standards in a vehicle that had been repeatedly stripped of anything deemed too heavy. Only lightweight wiring was used, there was no facility for hot water (and therefore hot meals), and even toothbrushes were cut from the checklist.

The spacecraft required an extensive set of gauges and controls, and reducing their weight was hard. The instrument panels were illuminated by electroluminescence, a new technique using phosphors instead of conventional light bulbs. (This proved so popular with the astronauts involved in the design of the LEM that it was adopted in the command module.) In the vehicle's final form, the left-hand wall contained banks of indicator lights which produced a gentle orange glow. Standing beside them, the commander would control the descent engine by gripping a throttle with his left hand, and the thrusters by holding a joystick with his right. In the centre panels between the two crewmen's positions, the gauges included a DSKY. The computer would be largely operated by the lunar module pilot, whose title was misleading since the spacecraft would actually be flown by the commander while the pilot monitored the instruments. Beneath the DSKY, a rectangular hatch opened on to a small platform known as the porch, while up above a telescope protruded into the cabin. Sections of the ceiling were covered with netting, to secure papers and other lightweight materials. Compartments for heavier items were built in to the lower sections of the walls and protected by white beta-cloth, a fireproof fabric.

Since the final phases of the landing would be controlled manually, the instruments' reliability was essential. Redundancy was built into the cabin layout with some controls duplicated on each side of the cockpit. The LEM had two computers, which worked independently of each other. The primary guidance and navigation system (PGNS, pronounced 'pings') relied on an inertial platform similar to its counterpart in the command module. The abort guidance system (AGS) consisted of a separate computer that gathered information from an independent set of movement sensors. Both computers could be updated either manually or by accepting data sent directly from Earth. They could also receive information from the LEM's two radar systems. A landing radar would begin to calculate the spacecraft's altitude once the crew had descended to below 40,000 feet. After the trip to the surface, a rendezvous radar would help the LEM find the command module from a distance of 400 miles. It could also be used in an emergency should the descent be aborted. Connecting the two radars to the guidance and navigation system proved to be one of the most complicated tasks in the development of the LEM. Equally challenging were the engines, which in 1966 were still beset by problems. That year, headquarters decided the word 'excursion' made the whole project sound like a holiday trip and it was decided the spacecraft should simply be called the lunar module.12

The astronauts would initially rely on the LM's life-support system, before switching over to the oxygen stored in their backpacks while preparing to open the hatch. This was originally round but was later changed to match the shape of the backpack, making it easier for the crew to leave the spacecraft. The hatch opened inwards and swung to the right so that whoever was to go first would need to be standing on the left. One plan envisaged the astronauts clambering down to the surface using a rope ladder, but this was later replaced with a real ladder, secured to one of the spacecraft's legs. While stowed aboard the Saturn the four legs were folded. Extended shortly before the descent, they contained crushable aluminium honeycomb to absorb the shock of the landing. Each was fitted with a round landing pad, beneath three of which dangled a six-foot-long probe designed to trigger a blue contact light in the cabin upon touching the surface.13 Armstrong feared that a fourth probe, directly below the ladder, might be bent dangerously upwards during the landing and he had it removed.

By early 1968 the finished product was finally ready to be tested.14 The world's only true spacecraft, the lander was designed purely for flight in a vacuum, and was not fitted with a heatshield. Nor was it aerodynamic. The propellant tanks for the ascent engine were contained in awkward external bulges, as if they had been bolted on at the last minute. Although it contained more than a million parts, from the outside the LM looked as if it had been thrown together by the winner of a children's competition. Adorned with thrusters, radars, transmitters and probes, its odd-shaped body, two bug-eye windows and four spindly legs gave it an almost sinister appearance. Michael Collins likened the LM to an enormous praying mantis, and he wasn't alone in mocking its odd appearance. Volkswagen used a picture of it in a Beetle advert, beside the line 'It's ugly, but it gets you there'.15 By the end of the programme 3,000 engineers were working for Tom Kelly, and although much of the spacecraft was eventually developed by committee, in later years he came to be known as the 'Father of the LM'.

Despite continuing concerns about the ascent engine, the first finished spacecraft, LM-1, was transferred to the Cape in preparation for Apollo 5, the unmanned test-flight of 22 January 1968. The Launch Control Center insisted that all rockets should carry a destruct mechanism in case anything went wrong. But the prospect of such a device inadvertently exploding while the crew were wandering about on the Moon led Houston to resist the Cape's demands, and eventually the rule was relaxed. Although Apollo 5 successfully achieved its objectives, the instability of the ascent engine continued to raise concerns that were not resolved until June 1968. Meanwhile, fears about the safety of the docking mechanism, allowing the LM to connect to the command module, dragged on into early 1969, further postponing Jim McDivitt's long-delayed mission. (A second unmanned flight, involving LM-2, was cancelled. Today, LM-2, the only intact lunar module to survive, can be seen at the Smithsonian Institution in Washington.)

Noted for his thoroughness and attention to detail, McDivitt, a former air force pilot, had been training to fly the LM since 1966. Regarded by Michael Collins as 'one of the best. Smart, pleasant, gregarious, hard-working, religious', McDivitt was one of the more conservative members of the Astronaut Office, certainly compared to his relatively free-thinking lunar module pilot Rusty Schweickart.16 Supported by command module pilot Dave Scott (Armstrong's dependable partner during Gemini 8), together they would be responsible for demonstrating the reliability of the final link in Apollo's chain of rocket stages and spacecraft modules. Manned missions had verified the safety of the rest of the hardware, but only the LM could carry astronauts the final few miles to the lunar surface. Already its development had put NASA behind schedule. Now, if McDivitt failed to prove the lander was up to the job, the challenge of reaching the Moon by the end of the decade could easily slip beyond reach. 'We were all cognisant of the time pressure,' McDivitt later said.

On 3 March 1969, the fourth Saturn V lifted off from the Cape, carrying with it Grumman's hopes of taking America to the Moon within the next nine months. For the first time, the complete Apollo package would test the sequence of manoeuvres required for a lunar mission, short of the landing itself. Launch flight director Gene Kranz subsequently wrote that the 'Apollo 9 mission was sheer exhilaration for both the astronauts and Mission Control'.17 For McDivitt, here was a rare chance to fly a spacecraft that was radically different to anything anyone had flown before. Operating LM-3 in Earth orbit, he and Schweickart planned to fly many miles away from the command module before returning for the critical rendezvous manoeuvre. For the first time since the rendezvous between Gemini 6 and Gemini 7 two spacecraft would be operating simultaneously, and to ease communications the crew were allowed to name their vehicles. The LM was given the call-sign Spider and the command module was named Gumdrop.

As Dave Scott prepared for the delicate task of using the command module to extract the LM from its container, he discovered that at this crucial point in the mission some of his thrusters weren't working. Flight controllers found the crew had accidentally pushed a switch, and through patient diligence they were able to correct the problem and keep the mission on track. Scott gingerly retracted the LM before taking the two spacecraft through a series of manoeuvres. The initial tests were due to include an EVA. Schweickart planned to leave the LM, and by using handrails mounted on its hull he intended to climb over to the command module. This would test an emergency procedure that could be used in the event of an unsuccessful docking. But after he suddenly vomited twice, plans for the space walk were scaled down to something less ambitious. Schweickart eventually performed a small EVA on the porch of the LM, testing the portable life-support system that would be worn on the Moon. At the same time Scott leant out of the command module hatch, and since both men were able to reach the handrails they successfully demonstrated that they could cross over in an emergency.

The next task for their 'tissue-paper spacecraft', as McDivitt called it, was to separate from Gumdrop and begin to pull away.18 For him and Schweickart there was more at stake than Kennedy's deadline. Failure to find the command module would be fatal, as without a heat-shield the LM would never survive reentry. 'When ... we finally pulled away from the docking mechanism,' McDivitt later recalled, 'I'm sure it was in Rusty's mind, I know darn well it was in my mind [that] we better get back to this place or we're going to be toast, and I really mean toast.' After covering more than 100 miles, they simulated an abort by ditching the descent stage and firing the ascent engine. McDivitt greatly enjoyed flying the ascent stage and found that its slender mass had the agility of a fighter jet. Waiting for his crew-mates to return, Scott eventually saw a vibrant pyrotechnic display cutting through the darkness as Spider's thrusters kept the LM on course for the rendezvous. The subsequent docking finally secured confidence in Grumman's claims to be able to bring men home from the Moon. 'We had a certain set of objectives, almost all of which were essential to the next mission,' McDivitt later said. 'We accomplished them, what more could we do? We were happy.' Chris Kraft recalled, 'I went home that night knowing that we could actually do this thing.'19

Despite the challenges, Kelly had produced a space-worthy vehicle that had performed up to expectation. Now NASA could push ahead with the next mission, this time testing the LM just a few miles above the lunar surface. George Mueller, the head of the Office of Manned Space Flight, even suggested that Apollo 10 should be given the landing, arguing that in making a low-level pass above the Moon the crew would be taking a great risk without much to show for it. But Mission Control wasn't ready for such a demanding flight and Mueller's demands were resisted. The debate was settled when it was established that Apollo 10's lunar module, LM-4, was too heavy to leave the surface safely. Apollo 10 would carry out the practice run while LM-5 would be made ready for the landing.20 Like its predecessors, LM-5 had suffered its fair share of problems – a window had blown out during a test, and fittings were replaced after cracks were discovered - but eventually the final component of Apollo 11 was declared ready for launch. Fully laden, LM-5 would weigh just short of 17 tons. If allowed to stand on its legs while full of fuel it would collapse under its own weight, even in the minimal gravity of the Moon.21 Only after burning a sufficient quantity of propellant would the spacecraft actually be able to land.

With the safe return of Apollo 9, and a decision made about Apollo 10, Armstrong, Aldrin and Collins began to feel a little clearer about their own mission.22 Unresolved issues were suddenly met with a new sense of urgency, not least the question of who would be first to walk on the surface. After Buzz had approached Deke in search of a Gemini flight, he had been deemed to be brash. Since then, in terms of intellectual ability, rendezvous expertise and EVA experience, Aldrin had proved himself to be one of the leading astronauts. While some questioned the way he had pursued the 'first out' issue, no-one could deny that it needed to be settled. His opinions could easily have been brushed aside but in fact they were addressed in a top-level meeting. Chris Kraft, the director of flight operations, Bob Gilruth, the director of the Manned Spacecraft Center, George Low, the Apollo office manager, and Deke Slayton, the director of flight crew operations, knew that whoever they selected would go down in history.23 Overnight they would become, in Kraft's words, 'an American hero ... beyond any soldier or politician or inventor'. Kraft was clear: 'It should be Neil Armstrong.'24

While Aldrin's talents were admired, the managers were not so much concerned with technical ability as with who would best serve as a representative of NASA. Three of them plumped for Neil, only Deke reserved judgement, but he was outvoted and the decision was carried.25 On 14 April, at a press conference in Houston, Low announced that 'plans called for Mr Armstrong to be the first man out after the Moon landing'.26 Deke explained to Buzz that in addition to Neil's seniority, Armstrong ought to leave first since Buzz would be hemmed in by the inward-opening hatch.27 Aldrin later suggested that this technical explanation was plausible and he was happy to accept it. But Michael Collins remembered that 'Buzz's attitude took a noticeable turn in the direction of gloom and introspection shortly thereafter'.28 With the question finally settled, the training regime could be amended and the crew once again could focus on the mission.

The question of how someone might train to land on the Moon was raised almost as soon as Kennedy had finished talking to Congress.29 The people best placed to provide answers were experienced test pilots. Men like Armstrong had spent years learning about the principles of aerodynamics and other key elements of flight – but none of this knowledge would be of much use in a vacuum. Working with data gathered from X-15 flights, and not much else, they would have to start virtually from scratch. A NASA study group, set up in 1961 at Edwards Air Force Base, took on the difficult and dangerous task of building a flying machine that could simulate flight in lunar gravity, which is just one-sixth that of Earth's.30 Initially, Armstrong was the team's only test pilot.31 Ironically, he found himself working on the problems that would be faced by whoever came to fly the first mission to the Moon. By chance, Bell Aerosystems in New York were working on the same idea and together the two groups agreed on a basic design that looked as if a jet engine had been dropped into a pile of scaffolding.32

Officially described as the lunar landing research vehicle (the LLRV), the machine was popularly known as the 'Flying Bedstead' due to its strange appearance. Armstrong considered it to be 'unconventional, sometimes contrary, and always ugly'.33 After leaving Edwards, Neil continued to monitor the development of the LLRV. While working on simulators and other NASA training facilities he ensured the two machines Bell sent to Edwards in 1964 met Houston's requirements.34 After the vehicle climbed to around 500 feet, the jet engine was throttled back until it supported five-sixths of the LLRV's weight. Once in 'lunar mode', the machine used a pair of throttleable thrusters to carry the remaining weight and simultaneously manage the rate of descent. A further 16 thrusters controlled roll, pitch and yaw, hissing as they fired jets of gas in short, sharp bursts. The machine had none of the controllable surfaces found on an aircraft, it was hard to fly, and the pilot was not enclosed in a cabin but found himself sitting in an ejection seat that was precariously perched on a platform. Dangerous as it was, the LLRV was regarded as a prototype lunar lander, and its value as such was quickly recognised.

While the LLRV was still being developed, Deke Slayton looked at alternative ways of teaching astronauts how to fly to the Moon. As well as operating in an unfamiliar gravity field, the lunar lander would have other characteristics that would be new to a jet pilot. Since it would be able to fly slowly above the ground without stalling, and would even be able to hover, Deke encouraged the men to learn to fly helicopters. Although they could replicate lunar descent trajectories, including hovering, helicopters could not simulate lunar gravity – something Armstrong knew had already been concluded while he was still at Edwards.35 The Lunar Landing Research Facility in Langley, Virginia, however, offered a closer taste of the real thing. The facility used cables and rigging to carry five-sixths of the weight of a replica lander that was suspended from an A-frame structure, 260 feet tall. Safer than a genuine flying machine, it allowed pilots to try things nobody would attempt in an LLRV. But its action was limited and ultimately so too was its value as an effective preparation for lunar flight. In some ways the closest comparison to the LM was an electronic simulator built by Grumman, which closely matched the interior of the spacecraft. Although it couldn't leave the ground, it was essential in developing an astronaut's familiarity with the LM's computers, radars and propulsion systems. Unlike the LLRV, the simulator offered only virtual risks, in that if anything went wrong the crew could simply switch it off and start again. Ultimately the best way to prepare for a trip to the surface of the Moon was to spend time using all of the available resources.

In early 1966 it was decided that the LLRV was of such value that three more would be built.36 The original two were sent from Edwards to Ellington Air Force Base, Houston, and all five were to be known as lunar landing training vehicles (LLTVs). The LLTV was to be given a more powerful jet engine, upgraded electronics, longer endurance in 'lunar mode' and a cabin that more closely resembled the cockpit of the LM (including the instruments).37 Beginning in the summer of 1966, a few months after his Gemini 8 flight, Armstrong periodically worked with Bell on the development of the LLTV, but it wasn't until March 1967 that he got his first chance to try it.38 After an initial test-flight, he didn't fly it again until the following year.

Dangerous as it was, Bill Anders believed that of all the astronauts Neil was particularly suited to machines that were difficult to handle because 'if it required something counter-intuitive or otherwise against the grain, he figured it out'.39 On 6 May 1968, Armstrong had been airborne for five minutes when the vehicle began to tilt sharply while he was just 200 feet above the ground. Unable to recover, by the time he had dropped to 100 feet the machine was tilting over so far he risked being propelled into the ground by his ejection seat. With less than a second to spare the seat rocketed him clear of the LLTV, and dangling beneath his parachute he hit the ground in front of groups of shocked onlookers.40

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Aboard the command module at the end of the third day the crew were beginning to set switches in the correct position, place blinds over the windows and turn down the cabin lights. During each rest period one man slept in a couch, with a lightweight headset taped to his ear in case Houston needed to call and a seatbelt fastened across his lap to stop him drifting into the instrument panel. The others used sleep restraints, which resembled light sleeping bags and were made of a mesh fabric with a zip down the middle. These were anchored beneath the two side couches where there was plenty of room to stretch out, the men's feet reaching towards the lower equipment bay.

They had not reached any firm conclusion about the unidentified object accompanying them at a distance of 100 miles or so. They presumed it was either debris from the spacecraft, or else one of the four panels that had enclosed the LM within its container.41 It was not the first mystery the crew had encountered during the mission. Buzz later recalled that while trying to doze at the start of the second night he had seen 'little flashes inside the darkened cabin, spaced a couple of minutes apart'.42 On two further occasions he saw 'double flashes, at points separated by maybe a foot'. Buzz believed something was penetrating the spacecraft, causing an 'emission' as it entered. He thought the second flash might occur when the object, whatever it was, struck part of the cabin. He realised that whatever was causing the flashes was coming from the direction of the Sun, and said as much to the others. Armstrong also saw flashes of light, counting more than 50 while looking into the spacecraft's interior over the course of an hour.43

Bill Anders, who flew to the Moon with Apollo 8 and who had a degree in nuclear engineering, later suggested the flashes may have been caused by 'cosmic radiation'.44 Radiation had long been a major concern for the Apollo mission planners, and flights were timed to avoid dangerous periods of solar activity. NASA's efforts to predict solar storms were proving to be successful. But the flight surgeons remained wary, and at the end of each day the crew dutifully reported their personal radiation measurements. It was later believed the flashes were taking place not inside the spacecraft but inside the eyeball, although their precise nature remains subject to speculation.

At 61 hours and 40 minutes into the mission, the astronauts were settling down for the night. They were now 186,400 miles from Earth and travelling at little more than 2,000mph. At this point, the spacecraft coasted out of the Earth's gravitational influence and slipped into the Moon's, although no physical evidence of this was felt by the crew. After Apollo 8 had reached this neutral point in space, flight controller Philip Shaffer told the press that in working out where the spacecraft was, Houston's computers were no longer using the Earth as a frame of reference but the Moon instead. On paper this meant the position of the spacecraft appeared to jump by several miles, and some reporters mistakenly wondered whether the astronauts had felt a jolt.45 Aboard Apollo 11, the crew were still unable to see their destination. They would nevertheless become aware of its presence as it pulled them towards it at a steadily increasing speed. Neil, Michael and Buzz were now held within the grip of the Moon – and come what may, they would soon be dragged towards its mysterious far side.