BACK INSIDE

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.