Category The First Men on the Moon

On the plan, 30 minutes had been allocated to documented sampling, which was to be a two-man activity. The first task envisaged Aldrin hammering a core tube into the surface. Armstrong was to take pictures prior to sampling, with the tube in the ground, and following its extraction. They were then to collect a number of rocks, each of which was to be photographed in situ, carefully lifted, and inserted into an individual sample bag. Although the lunar material was to be put inside a vacuum – sealed rock box, some material was to be put into a can which, when sealed, would retain any readily volatised constituents that would otherwise be difficult to preserve when the rock box was opened in the laboratory. Finally, if time permitted, they were to collect a second core sample. But when McCandless announced that only 10 minutes was available for this sampling it was decided to forgo the documentation.

While Aldrin prepared a core tube at the MESA, Armstrong disappeared out of sight of the television. Although he had been surprised to discover that, on looking east, he could not see the boulders that surrounded the large crater where Eagle’s computer would have tried to land, Armstrong was able to see the smaller crater over which he had passed just prior to landing. As this was only 200 feet away he decided to inspect it. Saying nothing of his intention, he set off, carrying the ALSCC.14 On reaching the southwestern rim of the crater he shot a sequence of 8 frames across the pit ranging from up-Sun, around the northern horizon and on down-Sun to Eagle. The crater had a raised rim and an interior strewn with rocks. He yearned to enter it to collect a rock as a treat for the scientists, but the pit was 70-80 feet in diameter and 15-20 feet deep and, in any case, he had to rush back. In all, his excursion had lasted just over 3 minutes. He had no difficulty sustaining a ‘loping’ gait, which the timing indicated to have been at 2 miles per hour.

‘‘Buzz,’’ McCandless called while Aldrin was still at the MESA attaching the extension handle to the core tube, ‘‘You’ve got about 10 minutes left now prior to commencing your EVA termination activities.”

“f understand,’’ replied Aldrin. A minute later he took the core tube and went to sample some already documented ground near the SWC. This ‘soil mechanics’ study was to determine soil density, strength and compressibility as functions of depth. ft would also reveal layering, either in terms of the chemical composition of the loose material or its physical characteristics, such as grain size. The plan called for the hollow tube to be driven to a depth of 18 inches. The staffs of the flag and the SWC had indicated that the surface material was consolidated at a depth of several inches, but Aldrin hoped that by hammering on the core tube he would be able to drive it in.

Armstrong would later express surprise that he had lugged Gold’s camera around with him for so long.

The extension handle came up to waist height. At first Aldrin raised the hammer only to chest level, but then he increased this to head level in order to generate the additional force. A complication was that the tube gained little support from the material it penetrated, and he had to maintain a grip on the tool with one hand throughout. As he became more determined, he observed that the hammer was denting the top of the handle. “I hope you’re watching how hard I have to hit this into the ground to the tune of about 5 inches, Houston,’’ he said pointedly. In fact, his hammering drove the tube in only 2 inches beyond the depth to which he had inserted it by hand. Giving up, he withdrew the tube from the ground. The finely grained material coated the section that had penetrated the ground. “It almost looks wet,’’ he noted. To his relief, the material did not dribble out of the open end. On his return, Armstrong snapped pictures of Aldrin at work, then accompanied him to the MESA to help him to cap the tube. A post-mission investigation concluded that the design of the aperture of the tube had inhibited penetration. In the expectation that the surface material would be loose to considerable depth, the core tube had been designed with an internal bevel to compact the material entering the tube as it was hammered into the ground, but because the lunar material at a few inches depth was close to its maximum density, it jammed in the aperture. This discovery made even more ludicrous the idea that the lunar surface was a dust trap that would swallow a spacecraft!

“Neil and Buzz,’’ McCandless called. “We’d like y’all to get two core tubes and the Solar Wind.’’ At Aldrin’s suggestion, Armstrong completed capping the first core tube, and Aldrin took the second sample 15 feet beyond where he had taken the first. “Buzz,’’ McCandless called as Aldrin hammered the second tube, “in approximately 3 minutes you’ll have to commence your EVA termination activities.’’ On realising that he was gaining no greater penetration than before, Aldrin withdrew the tube and returned to the MESA to cap it.

“Neil, after you have got the core tubes and the Solar Wind, anything else that you can throw into the box would be acceptable,’’ McCandless called.

“If you want to pick up some stuff,’’ Aldrin said to Armstrong, “I’ll get the Solar Wind.’’ Aldrin detached the collector sheet from its staff, rolled it up, and stuffed it into a bag. He discarded the staff. He deposited the SWC on the MESA next to the core tubes, ready for Armstrong to stow in the second rock box.

Meanwhile, Armstrong had used a pair of long-handled tongs to collect rocks for the ‘suite’ – a field geologist’s term for a collection of rocks representative of a site, including both the typical and the exotic. This was essentially as planned, but without documentation and with the rocks going into a single large bag rather than into individual bags.

‘‘Buzz,’’ McCandless called. ‘‘It’s time for you to start your EVA close-out.’’

‘‘That’s in progress,’’ Aldrin replied.

As the moonwalkers began to wrap up in silence, Columbia once again flew ‘over the hill’ and out of communication.

‘‘We’d like to remind you of the Close-up Camera magazine before you start up the ladder, Buzz,’’ McCandless called.

‘‘Have you got that over with you, Neil?’’ Aldrin asked.

Armstrong had dispensed with the ALSCC in order to collect samples. “No, the Close-up Camera’s underneath the MESA.” Having made an early report of what appeared to be vesicular rock and then retracted this claim, Armstrong had located some genuine examples, “I’m picking up several pieces of really vesicular rock out here, now.’’

“You didn’t get any environmental samples, did you?’’ Aldrin asked, referring to the material they were to have sealed into cans.

“Not yet,’’ replied Armstrong.

“Well, I don’t think we’ll have time.’’

“Neil and Buzz,’’ McCandless called. “Let’s press on with getting the Close-up Camera magazine and closing out the sample return containers.’’

Aldrin went to the MESA and, supporting himself with one hand, bent down to retrieve the ALSCC. After removing the film, he asked Armstrong to assist in inserting the magazine into his thigh pocket. “Anything more before I head on up, Bruce?’’

“Negative. Head on up the ladder, Buzz.’’

“Remember the film off of that,’’ Aldrin reminded Armstrong, referring to the Hasselblad.

“I will,’’ Armstrong promised.

“I’ll head on in, and get the LEC ready for the first rock box,’’ Aldrin said. As he ascended the ladder he noticed that the dust coating his boots made the rungs seem slippery. Armstrong was to have tried to dust him off, but there was no time.

Armstrong carried the bulk sample box from the MESA out in front of Eagle and hooked it to the LEC, then added the Hasselblad magazine to the same hook. “How are you doing, Buzz?’’

“I’m okay,’’ replied Aldrin, who was now inside the cabin. “Are you ready to send up the LEC?’’

The method for hoisting the box to the hatch required Armstrong to pull on the loop as if drawing washing along a clothes line. Watching, Joan Aldrin laughed, “God bless the rock box. I feel as if I’ve lived with that rock box for the last six months.’’ As the scene played out, she was amazed, “This is like a Walt Disney cartoon, or even a television show – it’s all too much to believe or understand.’’ As the lanyard thrashed in the weak lunar gravity, the film pack detached and fell to the ground by the forward leg. With the leading edge of the box nudging the upper rim of the hatch, Aldrin asked Armstrong to slacken off the tension in the tether in order to lower the box sufficiently to enable it to enter. While Aldrin was stowing the box, Armstrong retrieved the Hasselblad magazine. Because this had fallen beside the foot pad, he decided not to fetch his tongs from the MESA, and instead gripped the ladder with one hand and, bending at the waist, leaned to lift the magazine which, as with everything else that came into contact with the lunar surface, was coated with fine black dust.

“This one’s in. No problem,’’ reported Aldrin, having stowed the first box in its receptacle in the cabin.

At this point McCandless asked Armstrong for an “EMU check’’. Although this was nominally a request that he read out the status of his PLSS systems, the flight surgeon was concerned that in manhandling the rock box and working the LEC, his heart rate had shot up to 160 beats per minute, and the EMU check was a hint that he should take a rest.

“How’s it coming, Neil?” Aldrin asked a minute later.

Having placed the bag of rocks, core tubes and SWC into the second box and sealed it, Armstrong tethered the box and added the recovered magazine. “Boy,” he observed, “that filth from on the LEC is kind of falling all over me while I’m doing this.’’

“All that soot, huh?’’

To give Armstrong a rest, Aldrin suggested they revise the procedure for hauling up the box, “If you can just kind of hold it, I think I can do the pulling.’’

“Stand by a minute. Let me move back,’’ said Armstrong. He backed away to tension the LEC. Once the box was up, Aldrin detached the LEC from the pulley and tossed the cable out through the hatch. The uploading of the boxes had taken rather longer than in training, and repeatedly working against the restraint system built into the shoulder joints of the suit was the greatest exertion of the moonwalk.

“How about that package out of your sleeve, did you get that?’’ Armstrong enquired.

This was a reference to a small canvas bag of mementoes Aldrin had carried in his shoulder pocket with the intention of leaving it on the surface prior to his ingress; he had forgotten. Armstrong proposed that Aldrin pass him the bag once he was on the porch, but Aldrin tossed the bag out through the hatch and it landed at Armstrong’s feet. It contained a gold medallion bearing a representation of the ‘olive branch’ motif – one of four that Aldrin had in his personal preference kit, the others being destined for the astronauts’ wives. There was also an Apollo 1 mission patch in memory of Gus Grissom, Ed White and Roger Chaffee, who died when their capsule caught fire on the pad on 27 January 1967. On returning from his visit to the Soviet Union, Frank Borman handed over two medals that his hosts had requested be left on the Moon. These honoured Yuri Gagarin, the first man to orbit Earth, who died in an aircraft accident on 27 March 1968, and Vladimir Komorov, who died on 24 April 1967 when the parachute of Soyuz 1 failed to open. A more formal memento was a text bearing statements issued by Presidents Eisenhower, Kennedy, Johnson and Nixon, a message from the Pope, and messages of goodwill from the leaders of 73 countries of the United Nations. Some messages were handwritten, others typed, in a variety of languages. It also included a listing of the leadership of the Congress in 1969, a list of members of the committees of the House and Senate responsible for NASA legislation, and the names of NASA management. It was photographed and reduced by a factor of 200, transferred to glass for use as a mask for etching by ultraviolet light onto a 1.5-inch-diameter silicon disk – the same technology as was used to etch integrated circuitry. The disk bore the inscription ‘Goodwill messages from around the world brought to the Moon by the astronauts of Apollo 11’. Around the rim was ‘From Planet Earth’, and ‘July 1969’. Although silicon was chosen for its ability to withstand the temperature extremes of the lunar surface, it was enclosed in an aluminium container to protect the delicate crystal from shock. If it had been intended to mark the placement of these items, the moment had been lost.

Meanwhile, Houston, oblivious to what was going on, was eager to confirm that everything that was to have been loaded was indeed on board. “Neil, did you get the Hasselblad magazine?”

Armstrong had just stepped onto the foot pad. “Yes, I did. And we got about, I’d say, 20 pounds of carefully selected, if not documented, samples.’’

“Well done.’’

Grasping the ladder with both hands for stability, Armstrong adopted a deep knee-bend, then jumped, and his feet landed on the third rung from the bottom of the ladder! It was a shame, he would reflect, that they had not been able to remain out for longer. He had hoped to inspect the boulders off to the north, which, while distance was difficult to judge, appeared to be several feet across.

At T-3 minutes 45 seconds Paul Donnelly, the Launch Operations Manager in the Launch Control Center, wished the Apollo 11 crew, “Good luck, and Godspeed.’’

Ascent 123

By T-2 minutes the ‘boil off of liquid oxygen had ceased, and pressurisation was underway in all three stages of the launch vehicle. With one minute remaining on the clock, Armstrong reported, ‘‘It’s been a real smooth countdown.” Ten seconds later, the launch vehicle went onto full internal power. Because the apparatus was much too complex for the final phase of the preparations to be managed manually, at T-20 seconds an automatic sequencer took over. At T-17 seconds, the guidance system in the Instrument Unit was released. The phased ignition sequence for the five F-1 engines was initiated at T-8.9 seconds, with the vehicle being held down by four clamps. Knowing that no Saturn V had lit its engines and then not lifted off, the astronauts turned their heads in their ‘bubble’ helmets and grinned at each other – they were going to fly! Jack King, the Public Affairs Officer at the Cape, counted down the remaining seconds, ‘‘3, 2, 1,0. All engines running. Liftoff! We have a liftoff at 32 minutes past the hour. Liftoff on Apollo 11.’’

As the clock ran down through its final minute, Joan Aldrin had sat stiffly in a chair, close to tears, fidgeting nervously with a cigarette, twisting a handkerchief, flexing her hands. She watched in silence as the vehicle lifted off. Although in a room full of children, relatives and neighbours, she managed to capture a sense of solitude. In fact, everyone in the room was silent. In contrast, Pat Collins had been very focused, discussing aspects of the flight plan with Barbara Young, who had been through this on Apollo 10. At liftoff, Pat called out delightedly, ‘‘There it goes!’’

As the vehicle began to rise from the pad, a plug drawn from its tail started the master event timer in the spacecraft. NASA specified the timing of mission events in terms of Ground Elapsed Time (GET), as measured from ‘Range Zero’, defined as the last integral second prior to liftoff – in this case 09:32:00 Eastern Daylight Time on 16 July 1969. Armstrong’s heart rate was 110 beats per minute, Collins’s 99 and Aldrin’s only 88, in each case significantly lower than at this point in their Gemini flights. The first 12 seconds of a Saturn V launch were challenging, since the vehicle had to ‘side step’ away from the Launch Umbilical Tower, just in case a gust of wind pushed it towards the tower or one of the swing arms was tardy in rotating clear. As the vehicle gimballed its four outer engines to make this manoeuvre, it swayed this way and that; the effect being most pronounced at the top. As Collins observed later, ‘‘It was, I thought, quite a rough ride in the first 15 seconds or so. I don’t mean the engines were rough, and I don’t mean it was noisy, but it was very busy – that’s the best word for it; it was steering like crazy.’’ Once the vehicle had cleared the 400-foot-tall tower, operational control was handed to Houston. The Instrument Unit of the Saturn V now commanded an axial roll in order to align the vehicle with the flight azimuth. Armstrong was to report key events to Houston, and at an elapsed time of T+ 13 seconds he called, ‘‘We’ve got a roll program.’’ This was acknowledged by Bruce McCandless, a yet-to-fly astronaut serving as the Capsule Communicator (CapCom). Between T+13.2 and T + 31.1 seconds, the vehicle rolled from a pad azimuth of 90°E to a flight azimuth of 72°E. Once aligned, the vehicle started to pitch over in order to arc out over the Atlantic on the desired ground track. ‘‘Roll is complete,’’ called Armstrong, ‘‘and the pitch is programmed.’’

For the crowds, the first indication that a launch was in progress was a light at the base of the vehicle. A jet of flame passed through a hole in the Mobile Launch Platform to a wedge-shaped deflector, which split and vented it horizontally north and south. Water had been pumped onto the pad to diminish the acoustic reflection from the concrete, and the water in the pit was vaporised and blasted out with the flame as a roiling white cloud. The space vehicle weighed 6.5 million pounds, 90 per cent of which was propellant. ft was almost inconceivable that it could be raised off the ground, but the five F-1 engines, drawing propellants at the combined rate of 15 tons per second, yielded a total of 7.5 million pounds of thrust. As the vehicle slowly rose from the pad, exposing the flame, the intensity of the light rivalled the early morning Sun sufficiently to force observers not wearing sunglasses to squint their eyes. fn the press stand, positioned some 3.5 miles from the pad because this was calculated to be as far as an exploding Saturn V could shoot a 100-pound fragment, some of the photographers, their cameras forgotten, simply stood and yelled ‘Go!’ again and again. No launch since John Glenn’s had released such raw emotion in the press. At first it was like watching a silent movie, because the thunderous roar of ignition took 15 seconds to reach the official viewing sites. As the vehicle rose, the roar was overwhelmed by a staccato pop and crackle that was more felt than heard.[7] The ground shook sufficiently to register on remote seismic sensors. To some observers, it was debatable whether the Saturn V was rising, or its great thrust was pushing the Earth aside! Dee O’Hara and Lola Morrow had been joined at the astronauts’ viewing site by Beth Williams, wife of C. C. Williams, an astronaut who had been lost in an aircraft accident in 1967. Tears of joy streamed down their faces. On her boat 5 miles away, Jan Armstrong did not have a very good view, but she preferred reality to a television screen showing the narrow view from a long-range camera.

The main screen in front of the Mission Operations Control Room displayed a plot of the trajectory of the Saturn V, which was exactly as programmed. ff it were to suffer a guidance failure, Armstrong was ready to steer it himself, and was the first commander to have this facility. The vehicle passed through the region of maximum dynamic pressure at an altitude of 4 nautical miles,[8] while travelling at a speed of 2,195 feet per second. The slowly rising thrust from increasingly efficient engines, and the decreasing mass of the vehicle meant increasing acceleration. By design, the centre engine of the F-1 cluster shut down first to limit the acceleration. Once it had consumed some 4.5 million pounds of propellants, the S-fC was shut down. fts sustained thrust had compressed the vehicle lengthwise, and it snapped back to its true length when this force was suddenly removed, throwing the crew against their harnesses; this ‘eye-balls out’ shock being particularly harsh immediately after the peak ‘eye-balls in’ load of 4 g.8 As the 138-foot-long spent stage was released by pyrotechnic charges on its upper rim, small solid rockets in the fairings around its tail fired to retard it. Other such rockets on the exterior of the interstage pushed the remainder of the vehicle clear and gave ullage to settle the S-II’s propellants prior to firing its five J-2 engines. Already on the edge of space, the S-II was to combine continuing to climb with building up horizontal velocity. The spent stage followed a ballistic arc, 357 nautical miles long, into the Atlantic. Although staging occurred at an altitude of 36 nautical miles and 50 nautical miles downrange, it was visible to viewers at the Cape through thin high-level cloud.

The S-II was rather quieter than the first stage, built up its g-load gently, and ran smoothly. The role of the interstage was to prevent the discarded S-IC stage from coming into contact with the engines of the second stage. However, because it represented ‘dead weight’, it was promptly jettisoned. If it had been necessary to abandon the launch vehicle, the launch escape system would have been fired to draw the command module clear. The main solid rocket motor had a thrust of 150,000 pounds, which was fully twice that of the Redstone missile that fired Al Shepard on his suborbital Mercury mission. At an altitude of 60 nautical miles the escape system was jettisoned by firing a secondary solid rocket motor. The tower took with it the conical cover that had protected the command module during the ascent through the atmosphere and, if an abort had been made, would have protected it from the escape rocket’s exhaust. Up to this point, all windows except that in the hatch had been masked. With all five windows uncovered, the cabin brightened markedly.9 As it was above the bulk of the atmosphere, the S-II could manoeuvre without enduring significant aerodynamic stress. It was tasked with correcting any trajectory errors inherited from the first stage. As with the S-IC, the middle engine was shut down first. On fuel depletion, the outer engines cut off. One second later, at an altitude of 101 nautical miles, 875 nautical miles from the Cape and far beyond the range of the television cameras, the S-II was jettisoned to fall into the Atlantic. Joan Aldrin, who had fidgeted throughout, now went into her bedroom to check the abbreviated flight plan that she had pinned on the wall.

On igniting its single J-2 engine, the S-IVB continued to navigate towards the ‘keyhole in the sky’ for orbit. As it pitched over, it presented the astronauts with a view of the curved horizon across the Atlantic; however, being veterans, they had seen it before. At a downrange distance of 1,461 nautical miles, the Instrument Unit of the vehicle noted that it had attained the required combination of altitude and

A load of 1 g corresponds to an acceleration of 32.2 feet per second per second.

9 The cabin had five windows, numbered 1 to 5 running left to right: outboard of the left couch, in front of that couch, in the main hatch by the centre couch, in front of the right couch and outboard of that couch, with the side windows being large and rectangular, the hatch window being circular and the forward-looking windows being small and wedge­shaped.

velocity, and shut down the J-2 engine. At insertion,10 the vehicle was travelling at 25,567.8 feet per second in a ‘parking orbit’ that ranged between a perigee of 98.9 nautical miles and an apogee of 100.4 nautical miles, was inclined at 32.521 degrees to the equator and had a period of 88.18 minutes – which was within 0.6 foot per second and 0.1 nautical mile of the specified velocity and altitudes respectively. Apollo 11 was off to an excellent start.

To communicate with Apollo spacecraft, NASA had established the Manned Space Flight Network (MSFN) using ground stations, ships and aircraft linked to the Goddard Space Flight Center in Greenbelt, Maryland, and then on to Mission Control in Houston. Although some of the stations were simply voice-relays for Mission Control, others had radars to provide the tracking data required to enable the mainframe computers in Houston’s Real-Time Computer Complex to refine the parameters of the spacecraft’s orbit in order to calculate the translunar injection (TLI) manoeuvre.

Once the space vehicle had disappeared from sight, Arthur C. Clarke remarked to the BBC’s veteran space correspondent, Reginald Turnill, ‘‘At liftoff, I cried for the first time in 20 years – and prayed for the first time in 40 years.’’ The protestor, Reverend Ralph Abernathy, having ‘‘succumbed to the awe inspiring launch’’ said, ‘‘I was one of the proudest Americans as I stood on this soil; I think it’s really holy ground.’’

At 061:40, Apollo 11 entered the Moon’s sphere of influence. The strength of a gravitational field is directly proportional to the mass of the gravitating body and inversely proportional to the square of the range from the body. With Earth fully 81 times more massive than the Moon, the ‘neutral point’ was roughly 90 per cent of the way to the Moon; more specifically, 186,437 nautical miles from Earth and 33,822 nautical miles from the Moon. By this milestone, the velocity of the spacecraft had slowed to a relative crawl of 2,990 feet per second with respect to Earth and 3,272 feet per second with respect to the Moon. When Apollo 8 first blazed this trail, the less technically minded members of the press expressed surprise that the crew did not feel a jolt. The origin of this misunderstanding was a comment at a press conference by flight dynamics officer Philip C. Shaffer. After pointing out that Apollo 8 had slowed as it climbed from Earth, and beyond the neutral point accelerated towards the Moon, he added that as the spacecraft crossed the neutral point, the computers in the Real-Time Computer Complex, which constantly calculated its position and velocity, switched from a terrestrial to a lunar frame of reference and the way the numbers were crunched made it appear that the position of the ship had jumped several miles. There was, in fact, no physical manifestation of passing from one gravitational field to the other. Although Apollo 11 entered the Moon’s sphere of influence, it was not committed to it because, being on a free-return trajectory, if it were to do nothing it would pass around the back of the Moon and be deflected back to Earth.

Meanwhile, at home

During the overnight shift, those members of Glynn Lunney’s Black Team who had been asleep during the day and had missed the telecast of the LM inspection, watched a replay.

As soon as Aldrin had guided Armstrong in through the hatch, he reported, “The hatch is closed, latched, and verified secure.’’

The astronauts’ boots, lower legs and gloves were coated with the black lunar dust, and because the LEC had been coated with this material as a result of being trailed across the ground, dust had entered the cabin while hauling up the rock boxes. Some scientists had suggested that iron-rich material on the lunar surface might have been so modified by its long exposure to the charged particles of the solar wind that it would burst into flame on coming into contact with oxygen, and had expressed concern that the last that would be heard from Eagle would be a recital of the checklist leading to cabin repressurisation! Indeed, for several minutes as the cabin pressure built up to 4.8 psi of oxygen, the crew did not respond to calls – but they had not been consumed by flame, they were switching their umbilicals from the PLSS to Eagle’s communications system. On raising their helmets, they noted an odour that Armstrong compared to “wet ashes in a fireplace’’ and Aldrin to “spent gunpowder’’.

As Armstrong and Aldrin ran through their post-ingress checklist, Columbia, reappeared on revolution 19. McCandless brought Collins up to date, “The crew of Tranquility Base is back inside their base, repressurised, and are in the process of doffing the PLSSes. Everything went beautifully.”

“Hallelujah,” replied Collins.

In order to lighten the ascent stage, all items that were no longer needed were to be jettisoned. The extravehicular Hasselblad had been left on the MESA. The version for internal use was to be jettisoned, but first the astronauts used up their film by documenting the views from their windows showing the evidence of their activities. They were amazed at the number of boot prints. To finish up, they shot some interior views, obtaining an excellent picture of Armstrong looking deeply content.

Although the hatch had been open for 2 hours 31 minutes 41 seconds, they had spent longer on the PLSS systems due to having switched to the portable systems prior to opening the hatch, and remained on them for some time after its closure. As the rate at which they would consume coolant water was not accurately predictable

and they had required a margin in case of difficulty in reverting to the cabin’s life – support system, the nominal duration of the surface excursion had been set much shorter than the potential total duration of the backpack. To evaluate the cooling system of the PLSS, the water remaining in their tanks was poured out and weighed. It had been thought that Armstrong (by being outside for longer) would use some 5.4 pounds of coolant and Aldrin 5.1 pounds. In fact, Armstrong used a mere 2.9 pounds; Aldrin, however, used 4.4, this being due to his preference for intermediate cooling. As he reflected later, “I had cooler levels set on the (feed water) diverter valve because it just seemed to be pleasant that way. In retrospect, it appears that this leads towards a higher consumption of water. I wasn’t fully aware that when I was on a higher flow I would be pumping more water overboard. It wasn’t clear to me pre-flight that it would have such an effect on my water consumption. I certainly could have operated at lower levels without overheating.” Nevertheless, both men consumed significantly less water than expected, and could have remained outside for a longer period.

As they tidied up, Aldrin discovered that the button had snapped off a circuit breaker on the panel on his side of the cabin, and that of an adjacent breaker had been pushed in; evidently, while wearing his PLSS he had nudged the panel. The breakers were of the standard push-pull configuration used in aircraft. When the button was pulled to open the circuit it exposed a white band, and when pushed to close the circuit it hid the band as a visual cue. Although it would be possible to close the circuit by inserting the tip of a pen to set the latch, there would be no way to open it again. As the damaged breaker would be used to feed power to the ascent engine, the priority was to determine its current state. Houston said the telemetry indicated that it was open. It was decided to wait until the circuit was required, then use a pen to push it in; if it were to fail to latch, the designers had a manual workaround to feed power to the engine.

As the astronauts finished the post-moonwalk meal of cocktail sausages and fruit punch, Deke Slayton called to offer his congratulations, “I want to let you guys know that since you’re an hour and a half over your time line and we’re all taking a day off tomorrow, we’re going to leave you. See you later.’’

“I don’t blame you a bit,’’ replied Armstrong.

“That was a great day, guys. I really enjoyed it,’’ said Slayton.

“Thank you,’’ Armstrong said. “You couldn’t have enjoyed it as much as we did.’’

“It was great,’’ Aldrin added.

“We sure wish you’d hurry up and get that trash out of there, though,’’ Slayton urged.

“We’re just about to do it,’’ Armstrong assured him.

To depressurise the cabin they put their helmets and gloves back on and verified their umbilicals to the cabin’s life-support system. In view of the time it had taken to vent the cabin the first time, it was suggested that this time they should also open the valve in the overhead hatch. This reduced the depressurisation time to a mere 90 seconds. There were no communications while the hatch was open. Armstrong shoved out first one PLSS and then the other with sufficient force to clear the far end of the porch. The overshoes and helmet augmentation followed, together with the cabin arm rests, the body of the Hasselblad, a saturated lithium hydroxide carbon dioxide filter from the cabin system, urine bags and food packaging. The OPS were retained in case an external transfer to Columbia proved necessary.

Meanwhile, Columbia reappeared once again and McCandless called, “I guess we’ll bid you a good night and let you get some sleep, Mike.”

“Sounds fine,’’ agreed Collins.

Having flown a very ‘busy’ Gemini 10, Collins relished the day that he would have alone in Columbia. ‘‘I really looked forward to a chance to relax and look out the window – to get some assessment of what it’s all about.’’ He enjoyed the 48 minutes per orbit during which he was on the far side of the Moon. He would later write, in the style of a diary, ‘‘I’m alone now, truly alone, and absolutely isolated from any known life. I’m it. If a count were taken, the score would be three billion plus two over on the other side of the Moon, and one plus God-knows-what on this side. I feel this powerfully – not out of fear, or loneliness – but as awareness, anticipation, satisfaction, confidence, almost exultation. I like the feeling.’’

‘‘Repress complete,’’ Armstrong announced, ending Eagle’s period of silence.

‘‘We observed your equipment jettison on the TV,’’ said McCandless, ‘‘and the passive seismic experiment recorded the shocks when each PLSS hit the surface.’’

‘‘You can’t get away with anything anymore, can you?’’ laughed Armstrong in respect of their littering.

‘‘No, indeed,’’ McCandless agreed.

Several minutes later, McCandless was back, ‘‘We’d like to say, from all of us down here in Houston – and really from all of us in all the countries in the entire world – we think that you’ve done a magnificent job up there today.’’

‘‘Thank you, very much,’’ Armstrong replied.

‘‘It’s been a long day,’’ Aldrin noted.

‘‘Indeed,’’ McCandless agreed. ‘‘Get some rest there and have at it tomorrow.’’

‘‘Have you had enough TV for today?’’ Aldrin asked.

‘‘Yes, it’s been a mighty fine presentation.’’

‘‘Okay. Signing off. See you again tomorrow.’’ Aldrin pulled the circuit breaker to end the television transmission. The time in Houston was almost 3 am, and most people had already retired.

As McCandless went off-shift, he handed over to Owen Garriott of the Maroon Team, who posed a number of questions on various aspects of the surface phase of the mission. After accepting a deferment of a detailed description of the geology of the area, Garriott wrapped up with a question designed to assist in identifying their location, ‘‘You commented, Neil, that on your approach to the landing spot you passed over a football-field-sized crater containing blocks of rock 10 to 15 feet in size. Can you estimate its distance from your present position?’’

‘‘I thought we’d be close enough so that when we got outside we’d be able to see its rim back there, but I couldn’t. But I don’t think that we’re more than a half mile beyond it – that is, a half mile west of it,’’ Armstrong explained.

‘‘So you would estimate your position as less than half a mile, approximately, west of this large crater,’’ Garriott asked.

‘‘That’s correct,’’ Armstrong agreed.

With that, Garriott wished the crew of Eagle good night.

Armstrong and Aldrin had a 7-hour rest period scheduled prior to initiating preparations to liftoff. As a safety precaution against airborne dust they donned their helmets and gloves. Aldrin settled on the floor across the cabin, with his legs bent since the cabin was not wide enough to stretch flat. Armstrong reclined on the circular cover of the ascent engine, leaning against the aft wall and with his feet suspended above Aldrin in a sling improvised by hanging one of the waist tethers from the fixture installed for the LEC. With the windows shaded and the vehicle powered down, the temperature dropped. “The thing that really kept us awake, was the temperature,” recalled Aldrin. “It was very chilly in there. After about 3 hours it became unbearable. We had the liquid cooling system in operation in our suits, of course, and we tried to get comfortable by turning the water circulation down to minimum; it didn’t help much. We turned the temperature of our oxygen system to maximum; that didn’t help much either. We could have raised the window shades and let the light in to warm us but, of course, to do that would have destroyed any remaining possibility of sleeping.’’ The telemetry system allowed monitoring just one set of biomedical sensors. This indicated that although Armstrong was unable to fall into deep sleep, the period of inactivity permitted him to ‘wind down’ after the most momentous of days.

Meanwhile in the Sea of Crises

As Armstrong and Aldrin were attempting to sleep, the Soviet Union’s unmanned spacecraft Luna 15 tried to land and crashed. Sir Bernard Lovell, having tracked it using the 250-foot-diameter radio telescope at Jodrell Bank, estimated that it fell onto the Sea of Crises about 500 miles east of Tranquility Base. The Soviet news agency TASS reported, ‘‘The program of research in space near the Moon, and of checking the new systems of the automated station Luna 15, has been completed. At 6.47 pm Moscow time on 21 July, a retrorocket was switched on and the station left orbit and achieved the Moon’s surface in the preselected area.’’ If Luna 15 had managed to land and scoop up some material, it would, by virtue of not pausing in lunar orbit, have been able to return to Earth a day or so ahead of Apollo 11. Gerry Carr pointed out that the presence of the human pilot had undoubtedly saved Eagle from similar disaster. ‘‘Its computer was heading for a blocky crater, and Neil just intervened and moved it over a bit.’’ Although Soviet television had not shown the moonwalk ‘live’, a short clip was included in the news the next day. The People’s Republic of China, however, made no mention of the mission.

The USNS Vanguard had relayed communications as Apollo 11 entered orbit, then there was a hiatus until the spacecraft came within range of the tracking station on the island of Grand Canary, off northwest Africa. A valve in the command module had opened during the ascent through the atmosphere, and while its regulator had slowly allowed the cabin pressure to fall to 5 psi the environmental system started to increase the oxygen ratio and slowly purge the nitrogen that had been present to reduce the risk of a fire at sea-level pressure. Simultaneously, the pressure in the suits had also been reduced. For several hours prior to launch, the astronauts had been breathing oxygen at sea-level pressure to cleanse their bloodstreams of nitrogen, and on completing the post-insertion checklist they were able to doff their helmets and gloves, which were stowed in canvas bags. Despite the pre-breathing, Collins found that his left knee ached, as it had during his Gemini 10 mission, but in view of that experience he expected the discomfort to fade in a few hours.

‘‘Apollo 11,’’ McCandless called, ‘‘this is Houston through Canary.’’

‘‘Post-insertion checklist is complete, and we have no abnormalities,’’ reported Armstrong.

Insertion occurred at T + 709.33 seconds; this being S-IVB cutoff plus 10 seconds to allow for engine tail-off and other transient effects.

As they left Canary behind, Collins unstrapped himself from his couch and went to the lower equipment bay to unstow the equipment that they would require. In a gravitational field the vestibular system of the inner ear facilitates a sense of balance, but in weightlessness the fluid that yields these cues sloshes about freely. Despite having performed aerobatics a few days previously to ‘condition’ himself, he avoided sudden head movements that might induce disorientation.

‘‘Hey, Buzz?’’ Collins called.

‘‘Yes?’’

‘‘How would you like the camera?’’

‘‘Okay.’’

‘‘Here’s a Hasselblad for you.’’ The Hasselblad for internal use was fitted with an 80-millimetre lens.

‘‘Just a second!’’

‘‘I’ll just let go of it, Buzz; it’ll be hanging over here in the air – it’s occupying my couch.’’

A minute later, Collins asked, ‘‘Buzz, did you ever get that camera?’’

‘‘Yes.’’

‘‘Are you ready for 16-millimetre?’’

‘‘Yes. How about a bracket?’’

‘‘Neil will give you the bracket.’’

Collins unstowed the 16-millimetre Maurer ‘sequence camera’, also known as a Data Acquisition Camera, and gave it to Aldrin, who mounted it on a bracket in the right-hand forward-facing window ready to film the retrieval of the LM following TLI. It could run at 1, 6 and 12 frames per second on automatic, and 24 frames on semi-automatic, with shutter speeds of 1/60th, 1/125th, 1/500th and 1/1000th of a second.

‘‘I’m having a hell of a time maintaining my body position down here,’’ Collins complained, ‘‘I keep floating up.’’

After briefly checking in with Houston through the relay site at Tananarive on the island of Madagascar in the Indian Ocean, they crossed the evening terminator. As the ‘platform’ of an inertial measurement unit tends to drift out of alignment, it requires frequent resetting. While they were in Earth’s shadow, Collins was to run computer program 52 (referred to as ‘P52’) and take star sightings with the sextant in the wall of the lower equipment bay to realign the platform. At orbital insertion, the long axis of the vehicle was aligned with the velocity vector, with the sextant aimed towards space, and the S-IVB had established a pitch rate designed to maintain this ‘orbital rate’ attitude.

The platform used a nest of three gyroscopes and associated accelerometers to measure the spacecraft’s attitude and velocity with respect to the orthogonal axes of a coordinate system in a specified frame of reference. Different frames were to be used at different times during the mission, each specified by a ‘reference to the stable member matrix’ (REFSMMAT). As the spacecraft rotated, the platform tended to remain fixed in inertial space and the gimbals rotated to compensate. The platform, aligned to a REFSMMAT – the ‘stable member’ against which the gimbals tracked the attitude of the spacecraft – was the one reference that remained in the same position relative to the stars irrespective of what the spacecraft did. For the start of the journey, the REFSMMAT was defined (in part) with respect to the line from the centre of the Earth through the launch site at the time of liftoff and also with respect to the flight azimuth. This frame would be retained through to TLI. The optical system had a telescope and a sextant. The telescope gave a 60-degree field of view, without magnification, and was intended to be used to identify a constellation and aim the coaxial sextant in the direction of a given star. The sextant’s 1.8-degree field of view was magnified 28 times in order to make precise sightings. If the platform lost its sense of direction – which would occur if a pair of its three gimbals became co-aligned, locking them together (a condition appropriately known as ‘gimbal lock’) – Collins would run through this procedure to realign the platform from scratch. But when he merely wished to find out whether the system really knew its attitude, he would simply ask the computer to aim the sextant at a particular star, and check to see how far it was from the centre of the field of view, then mark its true position. With sightings on two stars, the computer could refine the alignment of the platform. As confirmation, he would then ask the computer to aim the sextant at a third star, which should then appear precisely centred in the field of view. With knowledge of its attitude and the ‘state vector’ specifying the spacecraft’s position and velocity, the computer could, at least in principle, calculate all the manoeuvres necessary to conduct the mission independently of ground support.

Explorers have been navigating on Earth by telescope and sextant for centuries. The computer served essentially the same function as the chronometer. The inertial system not only acted as a compass, but also measured acceleration, which was not a quantity needed on the surface. The digital computer was the technological marvel – a decade earlier, navigating in space would have been a considerably more manual process. Indeed, it could be argued that a lunar landing mission would not have been very practicable prior to the 1960s. The display and keyboard (DSKY, pronounced ‘disky’) of the computer was supplied by the Raytheon Company. It had a power supply, decoder relay matrix, status and caution circuits, a 21-character display unit, and a 16-button key pad with the digits ‘0’ through ‘9’, ‘VERB’, ‘NOUN’, ‘CLEAR’, ‘ENTER’, ‘PROCEED’ and ‘KEY RELEASE’. The executives, developed by the Instrumentation Laboratory of the Massachusetts Institute of Technology, were named ‘Colossus IIA’ for Columbia and ‘Luminary’ for Eagle, and used ‘programs’, ‘nouns’ and ‘verbs’. Verbs were the instructions to do something in the context of a program, while nouns represented the structures that were to be operated upon. For example, if Verb 06 Noun 62 was entered, the verb meant ‘‘display in decimal’’ and the noun indicated what was to be displayed (in this case three numbers of the spacecraft’s inertial velocity, vertical speed and altitude). Some programs had many verb and noun pairings. Numerical data took the form of five-digit quantities, scaled to fit and incorporating an implied decimal point. When a key was depressed, the appropriate item illuminated on the display. A verb would be flashed if the computer wished to attract attention when awaiting crew input. There were two DSKYs in Columbia – one on the main control panel, and the other in the lower equipment bay by the navigational instruments – and one in Eagle.

Star sightings were impractical while the spacecraft was in daylight because the particulates that the vehicle shed, and which floated alongside it, reflected sunlight and made it difficult to see the stars. But this material became invisible in Earth’s shadow. After jettisoning the external cover of the optical system and inserting the eyepieces into the sextant and telescope, Collins peered though the telescope. The view was not encouraging. “f think f am seeing the horizon, but I’m far from being dark-adapted; it’s hard to tell.’’ He installed the handles that were to enable him to hold his weightless body in position to use the instruments. Finally, to cover his left eye while viewing with his right, Collins donned a small plastic patch attached to an elasticated string. The computer knew the celestial coordinates of 37 naked-eye stars that were widely distributed across the sky, each identified by an octal (i. e. base 8) number.

With the vehicle maintaining a fixed attitude with respect to Earth while they remained in low parking orbit, there were only a few reference stars available for this initial P52 check, and the mission planners had decided which ones he should use. Collins told the computer to aim the optics towards star 30, Menkent in the constellation of Centaurus. As the view through the telescope was poor, he went straight to the sextant. The star was slightly ‘off. He centred the cross hairs of the sextant on the star and instructed the computer to record its true alignment. Then he asked for star 37, Nunki, in Sagittarius, checked it, and marked it. The Apollo sextant was more practicable than the hand-held version he had tested on the first orbit of Gemini 10, when John Young, his commander, had dubbed him ‘Magellan’ after the captain of the first ship to circumnavigate the world. Having marked two stars and told the computer to update the platform, Collins instructed it to find star 34 as a final check. ‘‘Atria is there in the sextant, but it’s not dab-smack in the middle.’’ He asked the computer to display the alignment discrepancy as a fraction of a degree. ‘‘0.01, Goddammit! Now that’s enough to piss a body off.’’ Glenn Parker, an instructor at the Cape, had bet him he would not achieve an accuracy better than 0.02 degree, and Collins had been sure he could attain a perfect 0.00 alignment. Finished with the optical instruments, he removed and restowed the eyepieces.

Carnarvon on the southwestern coast of Australia was operating three tracking systems to ensure that the parameters of the orbit were accurately measured, to enable Dave Reed, the flight dynamics officer in Houston, to calculate the TLI burn. After McCandless confirmed that there were no issues involving the S-IVB that might threaten the continuation of the mission, Collins, judging his bet to have been a tie, asked McCandless to pass on a message, ‘‘Tell Glenn Parker at the Cape that he lucked out – he doesn’t owe me a cup of coffee.’’

A black-and-white Westinghouse television camera with scan rate of 10 frames per second and 320 lines of resolution was carried on Apollo 7 and Apollo 8 with good results. A camera using the sequential colour technique was tested by Apollo 10, and issued to Apollo 11. Passing over Australia, Collins unstowed the camera and its ancillary apparatus and plugged in the power and signal cables. The camera was a rectangular box with a lens protruding from the front end. The monitor to enable them to see the field of view in order to verify the focus and lighting was the same width, about half the length, and slightly thicker, and had a small display

screen on one end. The flight plan called for a test of the system by sending to the Goldstone station of the Manned Space Flight Network, situated on a dry lake in the Mojave Desert near the town of Barstow in California. Having had no in-flight anomalies, they set off across the Pacific Ocean with 20 minutes of free time.

“How does zero-g feel?” Armstrong enquired of Collins, who was the only one to have left his couch.

“I don’t know,” Collins mused. “It just feels like we’re going around upside down.”

Indeed, they were, because the S-IVB was maintaining them in a ‘heads down’ attitude, but Collins was referring to the sensation of ‘full headedness’ that arises from the accumulation of blood in the head with the onset of weightlessness.

Passing south of Hawaii, the eastern horizon began to glow.

‘‘Stand by for sunrise,’’ announced Collins.

‘‘Neil hasn’t seen many of those,’’ pointed out Aldrin. Gemini 8 had performed an emergency return after only a few orbits, during which Armstrong had been too preoccupied to appreciate sunrise.

‘‘We haven’t got too many of them on this flight, so you might as well enjoy it while you can,’’ Armstrong advised.

By now the view ahead was a spectacular arc of colour.

‘‘Jesus Christ, look at that horizon!’’ Collins exclaimed.

‘‘Isn’t that something?’’ Armstrong agreed. ‘‘Get a picture of that!’’

‘‘Has anybody seen a Hasselblad floating by?’’ Collins asked. ‘‘It couldn’t have gone far, a big son of a gun like that.’’ He scrambled around looking for it. ‘‘Well, that pisses me off.’’ As he searched, he spotted a ball-point pen that should not have been floating freely. ‘‘I’ve looked everywhere over here for that Hasselblad, and I just don’t see it.’’

‘‘It’s too late for sunrise, anyway,’’ Armstrong lamented.

‘‘You want to get it before TLI,’’ Aldrin noted, referring to the camera. Objects floating freely would have to be collected and stowed prior to the manoeuvre, to prevent them slamming into something else and causing damage.

‘‘I know,’’ agreed Collins. As he continued his search, he endeavoured to avoid making movements that might induce ‘space sickness’. ‘‘Ah! Here it is, floating in the aft bulkhead.’’ He belatedly snapped a few pictures of sunrise.

‘‘How are we doing checklist-wise?’’ Armstrong prompted, several minutes later. ‘‘Let’s make sure we don’t screw up and forget something.’’

‘‘After I extend the docking probe,’’ Collins replied, ‘‘I have got to copy down a bunch of data, and you’ve got the RCS hot-fire.’’

As they approached Baja California, McCandless called via the relay station at Guaymas in Mexico to remind them that they were coming up on Goldstone, but the vehicle barely rose above Goldstone’s horizon and the station received less than 1 minute’s worth of the FM carrier signal without any image modulation. While this proved that the transmitter worked, it had yet to be demonstrated that the camera functioned. One point of progress, however, was that Collins decided that having the monitor float beside the camera was awkward, and that in future it should be taped on top of the camera.

Houston monitored the spacecraft’s telemetry to verify that the docking probe extended properly, and that the RCS thrusters in the quads positioned at 90-degree intervals around the service module imparted pitch, yaw and roll impulses – using only small ‘blips’ in order not to disturb the S-IVB. The Instrument Unit was then updated by direct uplink with the parameters of its orbit and the time and duration of the TLI manoeuvre. This data, plus information on options for an abort if that burn did not go to plan, was also read up to Collins, who wrote it on the flight plan and read it back for confirmation. It had once been intended that there should be a teleprinter to simplify the provision of such information, but this had been deleted in an effort to control the mass of the spacecraft. Because Goldstone had not been able to verify the television camera, as they passed over Florida they transmitted to the Merritt Island Launch Area where, although there was no longer any apparatus to process an image, it was possible to confirm that the carrier signal was modulated. McCandless reported via Canary Island on revolution 2 that the telemetry from the hot-firing indicated that one of the RCS quads was cold. On checking, Armstrong reported that the switch for the heater in that unit had been set incorrectly. ‘‘It was Off; it’s On now. Thank you.’’ With the heater operating, the unit rapidly warmed

up.

As Apollo 11 approached Earth’s shadow for the second time, Collins resumed his couch and they put their helmets and gloves back on in preparation for the TLI burn. McCandless attempted to call through Tananarive but received no response; it transpired that the remote station was not uplinking. Unconcerned, the astronauts worked on through the checklist.

FLIGHT DAY 4

As Apollo ll’s trajectory was predicted to produce a closest approach to the Moon of 62 (±2) nautical miles, as against the nominal 60, Glynn Lunney, leading the overnight Black Team, decided to cancel midcourse correction 4 and, as the crew would not now require to devote time to a P52 platform realignment and the other chores for the manoeuvre, he also decided to extend the sleep period either by two hours or until the astronauts awoke of their own accord.

When the scheduled wake-up time passed without word from Houston, Aldrin, who was standing watch, put in a call, “Houston, Apollo ll.” Getting no response, he repeated the call twice more.

It was approaching 6 am in Houston on Saturday, 19 July. “Good morning,” replied Ron Evans, making his first communication of the mission as ‘graveyard’ shift CapCom.

‘‘Are you planning midcourse correction 4?’’ Aldrin asked.

‘‘That’s negative,’’ said Evans. ‘‘We were going to let you sleep in until about 71 hours, if you’d like to turn over.’’

‘‘Okay. That’ll be fine.’’

Several minutes later, however, Armstrong and Collins also stirred, and it was decided to make an early start while remaining off the air until Houston made the formal call. Armstrong and Collins had slept 7.5 hours; Aldrin for only 6.5 hours. During this hiatus, Cliff Charlesworth’s Green Team began their shift, with Bruce McCandless as CapCom.

The astronauts’ wives had an early start, too. Jan Armstrong went out onto the lawn to give the photographers the first of their daily pictures. Pat Collins went to have her hair done, only to find that three female journalists also just happened to have appointments. On returning home, she took delivery of flowers from Annie Glenn, wife of John Glenn, with a card that stated: ‘May God watch over you and your family.’ Meanwhile, Joan Aldrin welcomed Michael and Rosalind Archer, her father and step-mother, who had just arrived from Pensacola, Florida. Rusty Schweickart and his wife Clare dropped off an enormous casserole of cold roast turkey with which to help feed the growing crowd.

“Good morning again,” said Aldrin when McCandless put in the formal wake-up call at 71 hours.

After relaying the flight plan updates, McCandless, with lunar orbit insertion imminent, returned to the low-pressure indication in the combustion chamber of the main engine during midcourse correction 2. “I’ve got a few words for you on the SPS engine performance.’’

“We’re ready to listen,’’ Armstrong replied.

“The onboard combustion chamber pressure reading is due to a known gauge calibration factor between what is in the chamber and what you’re reading on the gauge. We expect a single-bank operation to be 90 psi on the gauge for an actual chamber pressure of 95 psi; in dual-bank operation, a chamber pressure of 94 psi on the gauge is an actual of 99 psi.’’ The redundant propellant-feed valves of the engine were actuated by nitrogen and could be used individually (single bank) or together (dual bank). The lunar orbit insertion burn was to be done in dual-bank mode. A mission rule required the crew to cut short the manoeuvre if the chamber pressure fell below a given value, and McCandless clarified this. “Similarly, 80 psi on the gauge correlates to 83 psi actual, and we recommend that you stick to an LOI- termination-cue of 80 psi on the gauge – that is, no change to mission rules.’’

“Roger,” replied Armstrong. “We got all that.’’

Although Apollo 11 was now only 10,000 nautical miles from the Moon, the crew had not been able to see it since flight day 2 because the geometry of their trajectory meant that when they looked in that direction they were blinded by the Sun. With the spacecraft still in PTC, sunlight flooded in through a succession of windows, but while they were having breakfast the spacecraft passed into the Moon’s shadow and the cabin was suddenly plunged into darkness. Earth orbits the Sun at an average distance of 93 million statute miles. The visible surface of the Sun, known as the photosphere, is 860,000 miles in diameter, but this is surrounded by a very hot but tenuous atmosphere. This glowing corona is normally seen by Earthlings only when the Moon’s shadow falls on Earth during a total solar eclipse – having flown into that shadow, Apollo 11 had arranged its own eclipse. On looking out, the astronauts saw the corona projecting out behind the now large, but dark, lunar disk.

Deciding to take a picture, Collins asked McCandless to suggest an exposure for the corona. He got a typically comprehensive response. “We recommend that you use high-speed black-and-white film, interior lights off, the Hasselblad with the 80- millimetre lens and, as you’ll be hand-holding the camera, an f-stop of 2.8, with a sequence of time exposures at one-eighth of a second, one-half of a second, and, if you think you can steady the camera against something, exposures of 2, 4 and 8 seconds.’’

“It’s quite an eerie sight,’’ said Aldrin. “There’s a marked 3-dimensional aspect of having the corona coming from behind the Moon the way that it is.’’ From their perspective, with the Moon occulting the Sun, most of the lunar disk was revealed by ‘Earthshine’. The phases of the Moon and Earth are opposed, in the sense that when the Moon is a crescent, Earth is gibbous – which was the case at this point in the mission. Also, owing to their actual sizes, the angular diameter of Earth’s disk is fully four times that of the Moon as viewed from Earth. Furthermore, Earth has a

greater albedo, meaning that it reflects a higher percentage of the sunlight that falls on it. Thus, Earthshine illuminates the lunar nightscape more brightly than a ‘full’ Moon does a terrestrial night. ‘‘I guess what’s giving it that 3-dimensional effect is the Earthshine,” Aldrin mused. ‘‘I can see the crater Tycho fairly clearly – at least, if I’m right-side-up, I believe it’s Tycho. And, of course, the sky is lit all the way around the Moon.’’ From Apollo 11’s vantage point, it was possible to see a dark crescent of the hemisphere that faces away from Earth, with the limb silhouetted against the glowing corona.

‘‘The Earthshine coming through the window is so bright you can read a book by it,’’ Collins noted.

‘‘How far out can you see the corona extending?’’ McCandless asked.

‘‘I would suggest that along the ecliptic we can see the bright part of the corona out to about two lunar diameters; and perpendicular to that line, only one-eighth to one-quarter of the lunar radius,’’ Armstrong ventured. As their eyes adapted to the darkness, they saw the stars. ‘‘It’s been a real change for us. Now we’re able to see stars again and recognise constellations for the first time on the trip. The sky’s full of stars. It’s just like the night-side of Earth. All the way here, we have only been able to see stars occasionally, and perhaps through the monocular, but we haven’t been able to recognise any star patterns.’’

‘‘I guess it’s turned into night up there really, hasn’t it?’’ said McCandless.

‘‘It really has,’’ Armstrong agreed.

“If you have a minute or so free, we can read you up the morning news here,” McCandless offered a few minutes later.

“Let’s hear it,” Armstrong replied.

“Hot from the wires of the Manned Spacecraft Center’s Public Affairs Office, especially prepared for the crew of Apollo 11: First off, it looks like it’s going to be impossible to get away from the fact that you guys are dominating all the news back here. Even Pravda in Russia is headlining the mission, and refers to Neil as ‘The Czar of the Ship’; I think maybe they got the wrong mission.’’

Fred Haise read the next item, ‘‘West Germany has declared Monday to be ‘Apollo Day’. School children in Bavaria have been given the day off. Post Office clerks have been encouraged to bring radios to work, and Frankfurt is installing television sets in public places.’’

McCandless again, ‘‘The BBC in London is considering a special radio alarm system, to call people to their television sets in case there is a change in the EVA time on the Moon.’’

Haise, ‘‘And in Italy, Pope Paul VI has arranged for a special colour television circuit at his summer residence in order to watch you – that’s even though Italian television is still black-and-white.”

McCandless, ‘‘Here in Houston, your wives and children got together for lunch yesterday at Buzz’s house and, according to Pat, it turned out to be a gabfest. The children swam and did some high jumping over Buzz’s bamboo pole.’’

Haise, ‘‘In Moscow, space engineer Anatoli Koritsky, quoted by TASS, stated that Luna 15 could accomplish everything that has been done by the earlier Luna spacecraft. This was taken by the press to mean it could investigate gravitational fields, photograph the Moon, and then go down onto the surface to scoop up a bit for analysis.’’

McCandless, ‘‘Mike, even your kids at camp got into the news. Michael Junior was quoted as replying ‘Yeah’ when somebody asked him if his daddy was going to be in history. ‘What’s history?’ he asked, after a short pause.’’

After a sports round-up, Haise concluded with a novelty item, ‘‘You might be interested in knowing, since you are already on the way, that a Houston astrologer, Ruby Graham, says that the signs are right for your trip to the Moon. She says that Neil’s clever, Mike has good judgement and Buzz can work out intricate problems. She also says Neil tends to see the world through rose-coloured glasses, but he is always ready to help the afflicted or distressed. Neil, you are also supposed to have intuition that enables you to interpret life with feeling. Buzz is supposed to be very sociable, cannot bear to be alone and has excellent critical ability. Since she didn’t know at what hour you were born Mike, she has decided that you either have the same attributes as Neil or you’re inventive with an unconventional attitude that might seem eccentric to the unimaginative.’’

‘‘Who said all that?’’ Collins asked.

Haise laughed, ‘‘Ruby Graham, an astrologer here in Houston.’’

‘‘Tell Michael Junior that history or no history, he’d better behave himself,’’ Collins requested.

‘‘We’ll pass that along,’’ McCandless promised.

A few minutes later, Collins announced that he was going to halt PTC because the translunar coast was drawing to a close. By design, their trajectory would take the spacecraft in front of the Moon’s leading limb. However, because the Moon is 2,160 statute miles in diameter, and pursues its orbit around Earth at 2,287 miles per hour, this rendezvous required precise navigation through cislunar space.1 Although it was possible to enter lunar orbit by executing a single manoeuvre, if the engine were to fire for too long the spacecraft might dip so low thereafter as to crash. As the lunar orbit insertion (LOI) burn was required to occur on the far side of the Moon, out of communication, in planning Apollo 8 it had been decided to guard against this outcome by splitting the manoeuvre. The initial burn (LOI-1) would produce an orbit with a high apolune on the near side of the Moon, and the Manned Space Flight Network would track the spacecraft during the first two revolutions to make a precise calculation of the delta-V for the burn (LOI-2) that would circularise the orbit at the desired altitude, and this strategy had been retained by the later missions. Three hours before LOI-1 McCandless read up the details: time of ignition would be 075:49:49, the duration of the burn was to be 6 minutes 2 seconds, and the objective of the retrograde delta-V of 2917.3 feet per second was to achieve a lunar orbit with a perilune of 62 nautical miles and an apolune of 170 nautical miles. The loss of signal (LOS) as the spacecraft passed behind the Moon’s leading limb in the run-up to this manoeuvre was predicted at 075:41:23. If the burn was as intended, then the acquisition of signal (AOS) upon appearing around the trailing limb would be at 076:15:29. If for some reason the engine did not fire, acquisition would be 10 minutes earlier, and the gravitational ‘slingshot’ resulting from the encounter would have deflected the spacecraft’s trajectory back to Earth. If the engine were to cut off prematurely, then Apollo 11’s fate would depend upon whether the delta-V attained was sufficient to enable the Moon to capture it. If it attained an orbit with a very high apolune, this might possibly be lowered to continue the lunar phase of the mission. If, however, the burn did not last long enough to enable the Moon to capture the spacecraft, then it would emerge from the trailing limb heading into deep space and, in the event of the SPS being deemed unusable, their fate would rest upon whether it was possible to use the descent propulsion system of the LM to attempt a return to Earth; there was no guarantee.

At 075:30, after Charlesworth had polled his team, McCandless passed on the decision, ‘‘You’re Go for LOI.’’

‘‘Roger,’’ acknowledged Aldrin. ‘‘Go for LOI.’’

‘‘All your systems are looking good going around the corner, and we’ll see you on the other side.’’

In the event, only one of the four midcourse correction options had been necessary.

LIFTOFF AND RENDEZVOUS

Flight day 6, Monday, 21 July, started at 121 hours elapsed time with Ron Evans making his wake-up call to Columbia. In fact, Collins was already awake and was having his breakfast. Because Columbia was only a few minutes from going ‘over the hill’, Evans launched straight into updates to the flight plan which promised to keep Collins ‘‘a little busy’’: while in the Moon’s shadow he was to perform a P52 to align the inertial platform, and then, on starting the near-side pass of revolution 23, he was to track crater 130-prime in order to measure the plane of his orbit accurately prior to rendezvous.

Meanwhile, Evans called Eagle, ‘‘Tranquility Base, Houston.’’

‘‘Good morning,’’ replied Armstrong promptly.

When Evans asked how they had spent the night in the cramped cabin, Aldrin replied, ‘‘Neil rigged himself a really good hammock with a waist tether, and he’s been lying on the ascent engine cover. I curled up on the floor.’’ For breakfast they had bacon squares, peaches, sugar cookie cubes, and a drink made from pineapple and grapefruit.

In view of the program alarms during the descent indicating that the computer had been overloaded, and the fact that the ‘duty cycle’ would be 15 per cent greater during the ascent, Mission Control had decided to leave the rendezvous radar off until they reached orbit. As Columbia flew overhead on revolution 24, Eagle tested its rendezvous radar by tracking the CSM’s transponder. The inertial platform of the PGNS, which had lost its reference when powered down at the ‘T3’ milestone following landing, was aligned by taking star sightings with the telescope.

‘‘Eagle and Columbia, this is the backup crew,’’ announced Jim Lovell. ‘‘Our congratulations for yesterday’s performance, and our prayers are with you for the rendezvous.’’

‘‘Thank you kindly, Jim,’’ replied Armstrong.

‘‘Thank you, Jim,’’ Aldrin concurred.

‘‘We’re glad to have y’all looking over our shoulders,’’ Collins added.

As they waited for the appointed time to lift off, Armstrong called, ‘‘Houston, Tranquility Base is going to give you a few comments with regard to the geology

question of last night. We landed in a relatively smooth field of secondary craters, most of which have raised rims irrespective of their size, but that’s not universally true because a few of the smaller craters don’t have a discernible rim. The ground mass throughout the area is a very fine sand to a silt. I’d say the thing that would be most like it on Earth is powdered graphite. Immersed in this ground mass are a wide variety of rock shapes, sizes, textures, rounded and angular, and many with varying consistencies. As I said, I have seen what appeared to be plain basalt and vesicular basalt, others with no crystals, and some with small white phenocrysts of maybe 1 to less than 5 per cent. And we are in a boulder field where the boulders range up to 2 feet, with a few larger than that. Some of the boulders are lying on top of the surface, some are partially exposed and some are just barely exposed. In our traverse around on the surface, and particularly working with the scoop, we ran into boulders below the surface – probably buried under several inches of the ground mass. I suspect this boulder field may have some of its origin with this large sharp-edged rocky-rim crater that we passed over in the final descent. Yesterday I said that was about the size of a football field. I have to admit it was a little hard to measure, coming in, but I thought it might just fit into the Astrodome as we came by it. The rocks in the vicinity of this rocky-rim crater are much larger than those in this area. Some are 10 feet or so and perhaps bigger, and they are very thickly populated out to about one crater diameter beyond the crater rim. Beyond that, there is some diminishing. Even out in this area the blocks seem to run in rows with irregular patterns, and then there are paths between them with considerably less surface evidence of hard rocks.’’

“Thank you, very much,’’ acknowledged Evans.

As they ran through the checklist for liftoff, Aldrin used his pen to push in the damaged circuit breaker.

“For your information,” Evans reported, “the circuitry looks real fine on that ascent engine arm circuit breaker.’’ With this confirmed, Armstrong set the switch on the Engine Selector to Ascent.1

Glynn Lunney polled his Black Team on Eagle’s status, and Evans relayed the result, “Eagle’s looking real fine to us.’’

When Columbia appeared on revolution 25, Evans called Collins with another estimate for the position of the landing site, this time the one determined by Gene Shoemaker’s team of geologists, but as there was less than half an hour remaining to liftoff Collins was too busy to look.

“Our guidance recommendation is PGNS,’’ Evans advised Eagle, “and you’re cleared for takeoff.’’

“Roger. Understand,’’ replied Aldrin. “We’re number one on the runway.’’

Armstrong and Aldrin once again harnessed themselves to the floor to enable them to ‘stand’ upright while in flight.

The ascent propulsion system (APS) of Eagle was built by Bell Aerosystems, using

The options were, in turn, Descent, Off and Ascent.

an injector plate that was supplied by the Rocketdyne division of North American Rockwell. In all, the engine stood 4 feet 6 inches tall. Its combustion chamber was actually located inside the cabin, within a cylindrical cover that rose up from the floor, and its short nozzle sat on top of the central part of the descent stage. The only moving parts were the ball valves to allow propellants to flow to the injector. For redundancy, the primary valve was supplemented by a backup with a bypass line. It was required only that the valves open, since the hypergolic propellants would ignite on coming into contact in the chamber. If the computer command did not reach the valves, the circuit could be bypassed. Armstrong had suggested adding an option for manually operating the valves, but there had been no time. And, of course, the engine would require to burn long enough to enable the spacecraft to achieve some kind of orbit. If liftoff were delayed, Eagle would have to adopt a lower orbit in order to catch up with Columbia more rapidly, but if liftoff were to be so delayed that this would be impracticable, it was to climb to a high altitude and go passive, while Collins lowered Columbia in order to complete an ‘extra’ orbit to get into position to chase Eagle. There were many variations on this theme, depending on the circumstances, and Collins had a book detailing the procedures for each – all of which had been rehearsed in simulations. However, because Collins was allowed to descend to no lower than 50,000 feet, all of his options presumed that Eagle managed to attain at least this altitude. In a simulation in mid-June, the APS had shut down during ascent and Eagle had made up the velocity shortfall using a lengthy firing of all four of its downward-facing 100-pound-thrust RCS thrusters which, although nominally independent of the primary propulsion system, in an emergency could be fed from the main tanks to produce a sustained burn. On the possibility of the APS not igniting, Armstrong pointed out before the mission, ‘‘When pilots really get worried, is when they run out of options and run out of time simultaneously.’’ If it failed to fire, there were various procedures to try. Although Columbia would be able to remain in orbit for two more days before it had to set off for home, the issue would by then have been resolved, as Eagle’s power and oxygen would last no longer than 24 hours. Collins would later admit that his ‘‘secret terror’’ was that he would have to leave his colleagues on the Moon. As he told a reporter, ‘‘They know, and I know, and Mission Control knows, that there are certain categories of malfunction where I just simply light my engine and come home without them.’’

The White House had prepared a speech for President Nixon in case this were to occur: ‘‘Fate has ordained that the men who went to the Moon to explore in peace will stay on the Moon in peace. These brave men, Neil Armstrong and Edwin Aldrin, know that there is no hope for their recovery. But they also know that there is hope for mankind in their sacrifice. These two men are laying down their lives in mankind’s most noble goal: the search for truth and understanding. They will be mourned by their families and friends; they will be mourned by their nation; they will be mourned by the people of the world; they will be mourned by a Mother Earth that dared send two of her sons into the unknown. In their exploration, they stirred the people of the world to feel as one; in their sacrifice, they bind more tightly the brotherhood of man. In ancient days, men looked at stars and saw their heroes in the constellations. In modern times, we do much the same, but our heroes are epic men
of flesh and blood. Others will follow, and surely find their way home. Man’s search will not be denied. But these men were the first, and they will remain the foremost in our hearts. For every human being who looks up at the Moon in the nights to come will know that there is some corner of another world that is forever mankind.’’ Prior to making this speech, the President was to have telephoned the wives of Eagle’s crew. When it was evident that communications were nearing their conclusion, a clergyman was to have commended their souls in the manner of a burial at sea. Although macabre, it was only right and proper that such plans should be drawn up.

As the final minute ticked away, Armstrong issued a final reminder, “At five seconds to go I’m going to get Abort Stage and Engine Arm, and you’re going to hit Proceed.’’

“Right,” confirmed Aldrin.

“And that’s all,’’ Armstrong added wryly.

There was a ‘thud’ as pyrotechnics cut the structural and electrical connections between the two stages, and then the engine lit.

‘‘We’re off!’’ Armstrong announced.2

The television camera drew its power from the descent stage, but after the moonwalk Aldrin had pulled the circuit breaker to end its transmission through the high-gain antenna on the ascent stage. If they had erected the large self-standing antenna on the surface, it would have been possible to televise the liftoff. As they departed, Aldrin started the 16-millimetre Maurer camera that was mounted in his window in order to document their ascent to orbit.

It was just before 1 pm in Houston. Joan Aldrin was on the floor in front of the television. When Gerry Carr said Eagle had lifted off, she rolled onto her back and kicked her legs in the air (as she was wont to do), then stood up and leaned against the wall. ‘‘It’s strange,’’ she said, ‘‘from the beginning I have worried more about liftoff than touchdown.’’ This was perhaps because she had confidence in the astronauts’ ability to fly the vehicle, but at liftoff they were at the mercy of the hardware. ‘‘They’re on their way home!’’

After a prayer, Herman Clark, the Grumman quality control inspector who had checked out the APS of LM-5, had held his breath literally as well as figuratively as he waited for news; on hearing that the engine had lit he told himself, ‘‘Job well done, QC-wise’’, then resumed work checking another LM on the production line.

The APS plume shredded the foil that had covered the descent stage, sending fragments radially outwards. ‘‘Look at that stuff go all over the place,’’ exclaimed Armstrong. The plume did not stir up any dust, but Aldrin saw it blow the flag to the ground. The engine delivered just 3,500 pounds of thrust, but the ascent stage was light and it climbed rapidly, imposing a load of about 0.5 g. As it ascended, Aldrin remarked on its shadow, which raced over the surface. After 10 seconds of vertical rise, Eagle pitched over 45 degrees in order to begin to build a horizontal component to its velocity.

‘‘One minute and you’re looking good,’’ Evans advised.

Eagle had been on the surface for 21 hours 36 minutes.

The LM normally controlled its pitch and roll by using opposed upward – and downward-aimed thrusters to rotate the vehicle. However, as the upward-aimed thrusters would reduce the effect of the APS, it had been decided that during the ascent only the downward-aimed thrusters would be used, and firing the fore and aft thrusters in pairs to implement the progressive pitch-over produced a pronounced oscillation. “It’s a very quiet ride,” Aldrin noted. “There’s just a little bit of slow wallowing back and forth; not very much thruster activity.’’

“You’re looking good at 2 minutes,’’ Evans continued. “PGNS, AGS, and the MSFN all agree.’’

“We’re within 1 foot per second, AGS to PGNS,’’ Aldrin pointed out. If the PGNS navigation were to falter, the AGS would take over.

“Go at 3 minutes. Everything’s looking good,’’ called Evans.

“We’re going right down US One,’’ Armstrong pointed out. US Highway One was the main north-south route running between New York and Florida, and the astronauts had borrowed the name for a distinctive linear valley that astronomers knew as Hypatia Rille.

“We’ve got Sabine off to our right,’’ Aldrin announced. And a moment later, “There’s Ritter.’’ These were two large craters just beyond the western shore of the Sea of Tranquility. “And there’s Schmidt. Man, that’s impressive looking, isn’t it?’’ During their earlier orbital sightseeing, these craters had been in darkness.

The APS burned for the planned 7 minutes and inserted the spacecraft into orbit 166 nautical miles west of Tranquility Base. Its progress towards and across the terminator into darkness was monitored by the Madrid station of the Manned Space Flight Network. This showed a perilune of 9.4 nautical miles, an apolune of 46.7 nautical miles and a velocity of about 5,537 feet per second. The PGNS gave 9.5 by 47.3, and the AGS gave 9.5 by 46.6 – indicating that, all things considered, the redundant systems were in excellent agreement. Such a low orbit would readily be perturbed by the mascons, but this did not matter because the initial perilune would be raised during the rendezvous. The ascent had halved the 10,837-pound mass of the ascent stage, reducing it to 5,885 pounds.

Meanwhile, at home

Jan Armstrong listened to the ascent on her squawk box alone, while having a late breakfast. When she heard her husband call shutdown right on time she knew that, with Eagle in orbit, if it were to encounter any difficulties Columbia would be able to rescue it.

Back in space

In weightlessness, Armstrong and Aldrin expected the specks of dust which had settled on the floor of the cabin to float around and pose a health hazard, but most of it remained in place, seemingly because it had developed an electrostatic charge and become ‘clingy’. Free of the risk of inhalation or eye contamination, they were safely able to remove their helmets. The first in-orbit task was to do a P52 to check the inertial platform prior to initiating the rendezvous.

Columbia was oriented to point its radar transponder towards Eagle. Its VHF – ranging apparatus acquired Eagle at a range of 250 nautical miles, but the lock was intermittent. However, when Collins spotted the flashing beacon in the darkness he centred the cross hair of his sextant on it and instructed the computer to note the sighting. Eagle was to be the active partner in the rendezvous but if at any time it was unable to make a manoeuvre, Collins was ready to perform the ‘mirror image’ manoeuvre approximately one minute later, and take over the active role. The first rendezvous manoeuvre was calculated by Houston. The apolune of the initial orbit was on the far side. On nearing apolune, Eagle was to use its RCS thrusters to add 51.5 feet per second to lift the perilune. This coelliptic sequence initiation (CSI) manoeuvre gave an orbit of 46.1 by 49.5 nautical miles. On emerging from behind the Moon on revolution 26, the separation between the vehicles was 100 nautical miles and, since Eagle was lower and travelling faster, this was reducing at 99 feet per second. As a result of the perturbations by the mascons, Columbia’s orbit was 56.8 by 63.2 nautical miles. About one hour after CSI, the constant differential height (CDH) manoeuvre was a radial burn of 45 seconds for a delta-V of 9.2 feet per second to make the orbit coelliptical with and ideally 15 nautical miles below the orbit of Columbia. As Eagle caught up, Columbia ‘rose’ progressively above the horizon. About 40 minutes after CDH, with the separation at 38 nautical miles, the elevation reached 27 degrees and Eagle made the terminal phase initiation (TPI) manoeuvre, a 25-foot-per-second burn designed to set up an interception. Eagle had been tracking Columbia by radar, but now Armstrong was to track it visually and make lateral adjustments in order to hold his target ‘fixed’ against the stars, thereby ensuring that although the vehicles were tracing different arcs around the Moon, he made a straight-line (i. e. inertial) approach to Columbia. Shortly after the burn, Eagle passed ‘over the hill’. If things went to plan, by AOS on revolution 27 it would be station-keeping alongside Columbia.

The terminal phase finalisation (TPF) manoeuvre involved a series of small burns to refine the line of approach and, when the range was down to a few thousand feet, to brake in order to come to a halt within 100 feet of Columbia. It was a procedure perfected by the Gemini missions. The timing had been set to enable the terminal phase to occur in darkness, with Armstrong visually observing the flashing beacon on Columbia against the stars. The braking phase would occur just after emerging from the Moon’s shadow, to enable him to see and manoeuvre towards his target. This is the reason that this part of the mission, like so many other critical events, had to occur out of communication on the far side of the Moon.

Thus far, Columbia had been oriented to face its lower equipment bay towards the approaching spacecraft to enable Collins to use the sextant, but now he turned to point his apex towards the newcomer, and watched it from the left couch using the optical reticle in window 2, with the 16-millimetre Maurer camera in window 4 to document the remainder of the approach. He was delighted to see that Eagle remained centred in his reticle. Early in mission planning, Aldrin had noted that if the ascent stage was oriented ‘upside down’ as it finished the approach, this would obviate solar glare. As Eagle drew to a halt about 50 feet from Columbia, Collins took a series of Hasselblad photographs to document the state of the ascent stage.

During the terminal phase, Eagle had drawn ahead of Columbia, and therefore as the vehicles jointly flew around the limb he was able to snap his companion with Earth on the lunar horizon.

“Eagle and Columbia, Houston. Standing by,” Evans called to announce that communications had been restored.

“We’re station-keeping,” Armstrong replied, prompting sustained applause in the Mission Operations Control Room.

On 17 December 1903 on the beach at Kitty Hawk, North Carolina, Orville Wright achieved the first flight in a ‘heavier than air’ machine. On 20 May 1927 Charles Augustus Lindbergh took off in Spirit of St Louis at the start of the first successful solo flight across the Atlantic, tracing the ‘great circle’ route from New York to Paris. On 12 April 1961 Yuri Alekseyevich Gagarin became the first man to orbit Earth. In response, the following month President John F. Kennedy challenged his own nation to land a man on the Moon before the decade was out – and on 16 July 1969 Apollo 11 set off to do so.

By demonstrating that it was feasible to land on the Moon, it cleared the way for the later missions that undertook more ambitious lunar surface activities. Yet Apollo was an anachronism – an element of 21st century exploration provoked by the geopolitical tensions of the 1960s. When Sir Arthur C. Clarke was asked what event in the 20th century he would never have predicted, he said: ‘‘That we would have gone to the Moon and then stopped.’’ Nevertheless, at the time of Apollo 11 the Moon was viewed merely as the first step. At a press conference just beforehand, Thomas O. Paine, NASA’s Administrator, said: ‘‘While the Moon has been the focus of our efforts, the true goal is far more than being first to land men on the Moon, as though it were a celestial Mount Everest to be climbed. The real goal is to develop and demonstrate the capability for interplanetary travel.’’ This task remains to be fulfilled. In 2004 President George W. Bush directed NASA to resume human lunar exploration as a stepping stone to Mars. Perhaps by the time of the 50th anniversary of Apollo 11, mankind will once again be able to enjoy the excitement of a lunar landing.

As the mission of Apollo 11 is a story of exciting times, f have drawn on the mission transcript to recreate the drama. Quotations have been edited for clarity, for brevity, and to eliminate the intermingling that is characteristic of spontaneous conversation, but f have endeavoured to preserve the sense of the moment.

David M Harland July 2006

Acknowledgements

I would like to thank: Frank O’Brien, W. David Woods, Robert Andrepont, Ken MacTaggart, Hamish Lindsay, Gene Kranz, Gerry Griffin, Dave Scott, Mark Gray, Mick Hyde, Rich Orloff, Mike Gentry, Ed Hengeveld, Eric Jones, Stanley Lebar, Kipp Teague, Marc Rayman and, last but not least, Clive Horwood of Praxis.

The use of a parking orbit provided a full revolution of Earth in which to confirm that the S-IVB stage and the spacecraft were fully operational prior to attempting the TLI manoeuvre. The alternative would have been to time the launch to enable the S – IVB to undertake a single long burn directly onto a translunar trajectory. Such a manoeuvre was viable, but offered fewer contingency options. Specifically, if the spacecraft were to be found to have a fault that would require an abort and return to Earth, it would already be outbound by the time this became evident. However, the time spent in parking orbit posed a thermal issue for the S-IVB, which held liquid hydrogen at -423°F and liquid oxygen at -293°F. Nevertheless, the designers had cleverly exploited this fact, because as heat leaked in and caused the hydrogen to boil, the gas was vented through two small aft-facing nozzles for ongoing ullage to maintain the propellants settled in their tanks.

The burn was to begin at 002:44:14 and nominally last 5 minutes 47 seconds, but the Instrument Unit was programmed to terminate the manoeuvre when the desired velocity had been attained, and would therefore cut off early if the engine were to overperform and extend the burn if the engine underperformed. Armstrong was to allow it an additional 6 seconds before intervening, and asked Collins to monitor the duration and yell out at 5 minutes 53 seconds.

When Apollo 11 again came into range of Carnarvon, McCandless called with good news, “You are Go for TLI.”

“Thank you,” Collins acknowledged.

The S-IVB terminated its hydrogen venting, pressurised its propellant tanks, and ran through the pre-start sequence for the J-2 engine.

NASA had equipped several KC-135 aircraft as Apollo Range Instrumentation Aircraft, and stationed them in a line across the Pacific between Australia and the Hawaiian Islands. “They’re going to try uplinking both on S-Band and on VHF,” McCandless advised. “So if you make sure your S-Band volume is turned up, we’d appreciate it. We should have continuous coverage from now on, right through the TLI burn.’’

“Very good,’’ acknowledged Armstrong.

McCandless established a relay through ARIA 4 but the signal was noisy, so he switched to ARIA 3, which was much clearer. The aircraft relayed telemetry to Houston. “We just got telemetry back down on your booster,’’ McCandless advised, “and it is looking good.’’

“Everything looks good here,’’ Armstrong confirmed.

Although Apollo 11 would be the third mission to perform the TLI manoeuvre, it was by no means routine, as any major engine burn represented a potential point of catastrophic failure. The manoeuvre began in the vicinity of the Gilbert Islands, about half-way between Australia and Hawaii. The Instrument Unit was in control, but it provided cues to the spacecraft, and illuminated a lamp immediately prior to igniting the J-2 engine.

“Whew!’’ exclaimed Armstrong on the intercom circuit when the engine lit.

“We confirm ignition,’’ called McCandless, “and the thrust is Go.’’

“Pressures look good,’’ Armstrong noted.

“About 2 degrees off in the pitch,’’ Aldrin pointed out.

“I wouldn’t worry too much about that,’’ Armstrong advised.

The Real-Time Computer Complex was using the ARIA data to calculate the S – IVB’s departure trajectory, and any emergency course correction that the spacecraft would have to make in the event a shortfall in velocity.

“One minute,’’ called McCandless. “Trajectory and guidance are looking good, and the stage is good.’’

For the crew, the burn was silent. Although the engine was 110 feet behind and directed its plume aft, Collins noticed intermittent flashes of light through his side window. “Don’t look out of window 1,’’ he chuckled, “because if it looks like what I’m seeing out of window 5, you don’t want to know.’’

“Oh, I see a little flashing out there, yes,’’ Armstrong said.

From the centre couch Aldrin’s field of view was limited, but he looked across Collins, “Damn. Kind of sparks flying out there.’’

There was a lurch when, as programmed, the S-IVB adjusted the ratio of fuel to oxidiser being fed to the engine.

McCandless provided a reassuring update, “Thrust is good.’’

As the S-IVB consumed propellant and its structural dynamics altered, it began to vibrate. On Apollo 8 the amplitude of the vibration had caused Frank Borman to

consider aborting the burn. As the rattle built up, Aldrin became concerned that it might shake loose the Maurer camera that he had mounted in window 4. Collins, not wanting the camera to fall on his helmet, checked that it was secure.

As they climbed, they emerged from Earth’s shadow rather earlier than if they had remained in low orbit. The sunlight that suddenly flooded in made it difficult to read the instruments, but Armstrong had had the foresight to mount a card in his window to serve as a shade. “I’m glad I got my card up!’’

“Neil, that was a hell of a good idea,’’ congratulated Collins. “I can’t see very much.’’

“You are Go at 5 minutes,’’ McCandless advised.

As long as the J-2’s burn continued to within about 45 seconds of the intended duration, the mission would be able to continue by having the CSM later employ its main engine to make up the velocity shortfall. A greater shortfall would require an abort in which the CSM cancelled the result of the interrupted TLI and pursued a trajectory designed to end with a landing in the primary recovery zone, where the US Navy had ships already on station.

The S-IVB’s acceleration built up as it consumed its fuel and became lighter.

“What kind of g we pulling?’’ Aldrin asked.

“1.2, or 1.3 g, maybe,’’ Armstrong replied.

“Gee, it feels a lot more than that.’’

“Here we go,’’ announced Collins, as the nominal time for cutoff approached.

Two or three extra seconds passed, then the engine shut down.

“Shutdown!’’ called Armstrong.

Prior to the TLI manoeuvre, the vehicle had been in a nearly circular orbit at an altitude of about 100 nautical miles. The burn was to accelerate by 10,435 feet per second, to a velocity of 35,575 feet per second at an altitude of 174 nautical miles. At cutoff, it had attained 35,579 feet per second and 177 nautical miles, which was excellent by any measure. On the ground, the mass of the space vehicle had been 6.5 million pounds; at insertion into orbit it was slightly less than 300,000 pounds; it was now 138,893 pounds.

“Houston, that Saturn gave us a magnificent ride,’’ Armstrong announced. “We have no complaints with any of the three stages.’’ It was another great success for Wernher von Braun’s rocket team at the Marshall Space Flight Center.

The TLI manoeuvre inserted the vehicle into an elliptical orbit with an apogee beyond the orbit of the Moon. It did not shoot the spacecraft directly towards the Moon, but some 40 degrees ahead of the current position of the Moon in its nearly circular orbit of Earth. However, as the spacecraft neared apogee in three days’ time, the gravitational field of the now-present Moon would deflect its trajectory. If the spacecraft were to do nothing, it would pass around the ‘leading limb’ on a figure-of – eight ‘free return’ path that would send it back to Earth. However, the plan was to fire the main engine while behind the Moon in order to slow the spacecraft and enter lunar orbit.

Jack Riley was the Public Affairs Officer in Mission Control. “We’ve just had loss of signal as Apollo 11 passed behind the Moon. At that time we were showing its distance from the Moon as 309 nautical miles and its velocity with respect to the Moon as 7,664 feet per second. Here in the Control Center, two members of the backup crew, Bill Anders and Jim Lovell, have joined Bruce McCandless at the CapCom console. Fred Haise, the third member of the backup crew, just came in, too. And Deke Slayton, Director of Flight Crew Operations, is also present. The viewing room is filling up: among those on the front row are Tom Stafford, John Glenn, Gene Cernan, Dave Scott, Al Worden and Jack Swigert.’’

The inertial attitude of the vehicle was such that at its closest point of approach to the Moon the SPS engine would be facing the direction of motion, to serve as a brake. The CSM had redundant power buses, but in preparation for the burn these were ‘tied’ together to ensure that if one power supply were to fail this would not disrupt the operation of the systems at a critical time.

‘‘I’ve turned the S-Band volume down to get rid of that background noise,’’ Collins announced, ‘‘so don’t forget that we have to turn it back up on the other side!’’

With 2 minutes to go, they emerged from the Moon’s shadow. As they had been flying ‘on instruments’, Collins looked out of the window to visually confirm that they were in the correct attitude. ‘‘Yes, the Moon’s there, in all its splendour.’’

As they raced across the terminator, the deeply shadowed terrain appeared to be extremely rough. ‘‘Man,’’ exclaimed Aldrin, ‘‘look at it!’’

‘‘Don’t look at it!’’ said Armstrong, drawing their attention back inside. ‘‘Here we come up to ignition.’’

At 5 seconds to go, the computer flashed ‘99’ in the Verb display of the DSKY, to ask the crew whether they wished to go ahead with the burn as specified. ‘‘99’’, noted Collins.

‘‘Proceed,’’ commanded Armstrong.

Collins hit the PROCEED key to tell the computer to execute the manoeuvre. ‘‘Stand by for ignition.’’ Armstrong’s heart rate was 106 beats per minute, Collins’s was 66, and Aldrin’s was 70.

Two RCS thrusters fired briefly to settle the propellants in the main tanks, and then at the appointed time the computer ignited the SPS engine.

‘‘Burning!’’ confirmed Armstrong.

‘‘What’s our chamber pressure?’’ Collins asked.

The gauge was below the left FDAI. ‘‘It’s good, 95,’’ confirmed Armstrong.

‘‘The PUGS is oscillating around,’’ noted Aldrin. The Propellant Utilisation Gauging System measured how the engine was drawing fuel and oxidiser. Aldrin was to use a knob to maintain the correct combustion mixture, but this was tricky due to the lag in response.

‘‘Okay, we’re steering,’’ noted Collins. ‘‘The gimbals are a little busier than I’d have expected, but everything’s looking good.’’ The engine gave a load equivalent to one-fifth gravity. ‘‘The g feels sort of pleasant.’’

‘‘Tank pressures are good,’’ Aldrin confirmed.

“The chamber pressure is building up a little bit; 96 now,” Armstrong noted as he monitored the gauge.

“That’s a little more chamber pressure than they were predicting,” pointed out Collins, thinking of the miscalibration.

“Chamber pressure is continuing to rise,’’ added Armstrong a moment later, “it’s up to about 98 psi.’’

“We’re wandering off a little bit in roll, but that’s to be expected,’’ observed Collins. “It’s coming back.’’

The high chamber pressure would reduce the duration of the burn, but that was not the critical issue; what mattered was the change in velocity, and the computer would shut down the engine when the required 2,917.3-foot-per-second change in velocity had been attained. “Cutoff is going to be about 3 seconds early,’’ warned Aldrin.

“Nominal cutoff is at 6 + 02,’’ Collins noted, “so expect it around 6 minutes even, huh?’’

“I’m predicting 5 + 58, 4 seconds early,’’ said Armstrong. “Maybe 5 seconds.’’

“She’s steering like a champ,’’ Collins said. “The rates are wandering, but in all three axes they’re plus or minus 0.1 degree.’’

“Five seconds early, at 5 + 57,’’ Armstrong updated. “The chamber pressure is 100 psi even.’’

Collins counted down the seconds to the predicted cutoff.

“Shutdown!’’ confirmed Armstrong.

As they ran through the post-burn checklist, Collins prompted the computer to display the discrepancies between the desired and achieved velocity as measured in the three-coordinate system. “Minus 1, minus 1, plus 1; Jesus!’’ The ‘residuals’ were only 0.1 foot per second; the burn was essentially perfect. ‘‘I take back any bad things I ever said about MIT – which, of course, I never have.’’

Aldrin glanced out at the Moon. They were now well past the terminator and the terrain was well lit. ‘‘I have to vote with the Apollo 10 crew that the surface is brown.’’

‘‘It sure is,’’ agreed Collins.

‘‘It looks tan to me,’’ said Armstrong.

‘‘But when I first saw it, at the other Sun angle it looked grey,’’ Aldrin noted, referring to just prior to the burn. ‘‘It got more brown with increasing Sun angle.’’

Armstrong again drew his colleagues’ attention inside, ‘‘Alright, now we’ve got some things to do.’’

As they continued through the checklist, Collins said, ‘‘Well, I don’t know if we’re 60 miles or not, but at least we haven’t hit that mother.’’

The computer displayed the parameters of their orbit. ‘‘Look at that!’’ Aldrin exclaimed, ‘‘169.6 by 60.9.’’

‘‘Beautiful, beautiful, beautiful, beautiful!’’ enthused Collins. ‘‘Write it down just for the hell of it: 170 by 60, like gangbusters.’’

‘‘We only missed [apolune] by a couple of tenths of a mile,’’ Aldrin added in amazement.

It is not possible to orbit Earth at an altitude of 60 nautical miles, as this would be subject to the drag of the upper atmosphere. However, the Moon is airless. It is also smaller and less massive and, since its gravity is weaker, a spacecraft in orbit is not required to travel so fast. On the other hand, because the orbit is smaller, the period – at about 2 hours in this case – is only marginally longer than for a low orbit around Earth.

“Hello, Moon,” Collins greeted. “How’s the old back side?”

“Now,” said Armstrong, “the flight plan says we roll 180 degrees and pitch down 70 degrees.’’

“What are we pitching down for?’’ Collins asked. Then he laughed. “I don’t know what we’re doing.’’

Armstrong enlightened his CMP, “We’re going to roll over and pitch down so that we can look out the front windows down at the Moon!’’

“Oh, yes, okay,’’ Collins acknowledged.

As the spacecraft slowly executed the 180-degree roll, Collins asked, “Can we see the Earth on the horizon from here?’’

“We should be able to,’’ Armstrong replied.

Collins decided they should take a picture of their first Earthrise. “Big lens or small one?’’

“For the Earth coming up, we want the 250-millimetre,’’ decided Aldrin, as he started to assemble the Hasselblad. “Infinity, at f/11 and 1/250th, huh?’’

“Is it loaded with black-and-white, or colour?’’ asked Collins.

“Colour.’’

“Alrighty!’’ said Collins, satisfied.

“We ought to wash this window,’’ Aldrin said. “Anybody got a Kleenex?’’

Both Armstrong and Collins offered towels.

“Well, one more SPS burn,’’ Collins mused, thinking of completing the lunar orbit insertion sequence.

“Two more!’’ corrected Aldrin, remembering that the engine would also have to make the transearth injection burn if they were to get home.

Meanwhile, at home

Jan Armstrong had Barbara Young over for lunch. Having been through lunar orbit insertion on Apollo 10, Barbara described how she had had an anxious wait when her husband’s flight had reported back fully two minutes later than expected, raising the prospect of the burn having slowed that vehicle so much that it would crash. However, Jan was more concerned that AOS might be early, indicating that the burn had not occurred and the spacecraft was heading back to Earth on the free-return trajectory, because she knew that to lose the opportunity to attempt to land would be devastating for the crew’s morale. “Don’t you dare come around,’’ she muttered as the no-burn time approached. “Don’t you dare!’’ When that moment passed with no signal, she delightedly exclaimed “Yippee!’’

Back in space

“Look at those craters in a row. Something really peppered that one,’’ Collins said, drawing attention to the lunar surface. “There’s a lot less variation in colour than I would have thought, you know, looking down?’’

“But you’d say it’s brownish?” Aldrin asked.

“Sure.”

“Oh, golly, there’s a huge, magnificent crater over here,’’ exclaimed Aldrin. “I wish I had the other lens on. God, that’s a big beauty. You should look at that guy, Neil.’’

“I see him,’’ Armstrong said.

“Well,” said Collins, “there’s really no doubt that the Moon is a little smaller than the Earth; look at that curvature.’’

Aldrin suggested that as they still had about 10 minutes to AOS, they ought to switch the Hasselblad to a ‘wider’ lens in order to shoot the lunar landscape.

“Just don’t miss that first one,’’ urged Collins, eager that they should record their first Earthrise.

The landscape passing below was fascinating.

‘‘What a spectacular view!’’ remarked Armstrong.

‘‘There’s a hole down here you just wouldn’t believe,’’ Collins pointed out. ‘‘And there’s the biggest one yet. God, it’s huge! It’s enormous! It’s so damned big I can’t even get it in the window! You want to look at that? That’s the biggest one you ever seen in your life. Neil? God, look at this central mountain peak.’’

Meanwhile in Houston, Jack Riley, continuing his public commentary, noted, ‘‘It’s very quiet here in Mission Control. Most of the controllers are seated at their consoles, several are standing up. We’re now 7 minutes from the acquisition time for the nominal burn. If Apollo 11 attained only a partial burn, we could receive a signal at any time.’’

‘‘Isn’t that a huge one?’’ Collins exclaimed, indicating another crater as they continued around the Moon’s far side. ‘‘It’s fantastic! Oh, boy, you could spend a lifetime just geologising that one crater alone!’’ After pausing to reflect, he added, ‘‘Although that’s not how I would like to spend my lifetime!’’

‘‘There’s a big mother over here, too,’’ Aldrin pointed out.

‘‘Come on now, Buzz,’’ Collins chastised, ‘‘don’t refer to them as ‘big mothers’ – give them some scientific names.’’

‘‘It sure looks like a lot of them have slumped down,’’ noted Aldrin, referring to the terraced rims of the craters, which had indeed slumped into the pit.

‘‘A slumping big mother!’’ exclaimed Collins. ‘‘Well, you see those every once in a while.’’

‘‘Most of them are slumping,’’ continued Aldrin, ignoring Collins. ‘‘The bigger they are, the more they slump.’’

‘‘We’re at 180 degrees,’’ announced Armstrong as he terminated the roll, ‘‘and now we start a slow pitch down about 70 degrees.’’

‘‘We’ve got 4 minutes to get pitched down before AOS,’’ pointed out Aldrin. ‘‘We’ll never make it.’’

‘‘Goddamn, a geologist up here would just go crazy,’’ suggested Collins. ‘‘We shouldn’t take any more pictures on this roll until we get Earth.’’

‘‘We might make it in time,’’ said Armstrong, referring to the timing of their pitch manoeuvre.

‘‘There it is,’’ exclaimed Aldrin. ‘‘It’s coming up!’’

“What is?” Collins asked.

“The Earth!” explained Aldrin. “See it?”

“Yes. Beautiful.”

“It’s halfway up already,” Aldrin noted. He snapped a picture, but not having changed back to the 250-millimetre lens it was not the close up Collins desired. “We ought to have AOS now,’’ Armstrong pointed out.

The antenna in Madrid acquired the carrier signal right on time, indicating a good burn.

“AOS!” Riley announced to the public.

“Apollo 11, this is Houston. Do you read?’’ prompted McCandless. Although Armstrong replied with a full burn report, the high-gain antenna had yet to lock on and the transmission by omnidirectional antenna was so noisy that he was mostly unintelligible. “Could you repeat your burn status report?’’ McCandless requested. “It was perfect!’’ Armstrong replied simply.

Once the high-gain link had been established, the flight controllers examined the telemetry. Going ‘over the hill’, the combined mass of the two spacecraft was 96,012 pounds. The LOI-1 burn had consumed 24,008 pounds of propellant.

Meanwhile, at home

Joan Aldrin, who was at the hair-dresser, was listening to the radio coverage of the mission. In her house, Rusty Schweickart was explaining to the assembled crowd that the manoeuvre had gone to plan.