Night time on a sunlit world

The lunar day. as measured from sunrise to sunset, lasts for about 14 Earth days and therefore, the crew’’s circadian rhythm had to be maintained artificially. When it was time to sleep, the best that could be done was to put shades up over the LM’s three windows while the unfiltered Sun, rising slowly in the east, beamed down on the spacecraft’s exterior.

Unfortunately, the first three crews on the surface had to remain in their suits for the duration of their stay. The LM’s operational lifetime w? as very short, there was concern about the effect of dust on the zippers and the additional time required to get out of and back into their suits was considered too expensive. They simply had to endure an uncomfortable rest period. Once Armstrong and Aldrin had discarded their PLSSs out of the cabin, they could arrange things for the night. Aldrin lay across the floor in front of the hatch, his knees bent to allow for the confined space. Armstrong perched himself on top of the ascent engine. His head was towards the back of the cabin near a noisy coolant pump while his legs dangled above Aldrin supported by a lash-up he had fashioned from a cord in the spacecraft.

Their attempt to put the lights out was less than successful. Armstrong noted after the flight that, on top of the fact that the shades turned out to be not as opaque as they w’ould have liked, there w’ere several warning lights and luminous switches that could not be dimmed. And there was a final, more troublesome source of light. "After I got into my sleep stage and all settled down, I realised that there was something else shining in my eye. It turned out to he that the Earth was shining through the [telescope] right into my eye. It was just like a light bulb.”

They had elected to sleep with their helmets on in an attempt to limit the noise from the spacecraft and to keep front breathing the pervasive dust. But now that they had settled down and were no longer active, they began a battle with the environmental control system to stay wann. “We were very comfortable when we completed our activities and were bedded down.’’ continued Armstrong. "After a while, I started to get awfully cold, so I reached in front of the fan and turned the water temperature to full up. It still got colder and colder. Finally, Buzz suggested that wc disconnect the water, which 1 did. I still got colder. Then. I guess, Buzz changed the temperature of the air flow’ in the suit.”

The next two crews fared only a little better, even though they didn’t get cold, thanks to procedural changes after Apollo 11, and they had hammocks across the cabin to make their rest more comfortable. Conrad had made a small error with the sizing of his suit shortly before the flight and he paid for it during his rest period with the resultant pressure on his shoulders. Bean then spent an hour making adjustments to the legs of Conrad’s suit to relieve the pressure.

Bean also struggled to get some proper rest as he explained after the flight. "I think I didn’t sleep well because I was just nervous and excited.” How’ever, there was a solution in the medical kit, if he chose to use it. "If 1 did it over again, 1 would take a sleeping pill on the Moon." Bean’s explanation hinted at the issues NASA would have to deal with before the J-missions began, each involving three 7- hour EVAs. "I felt like I was tired towards the end of the second EVA and I felt like it w’asn’t from the physical effort. It was from the lack of good sleep. I didn’t take the pill because it was not a macho thing to do, [but] 1 felt like 1 was really running out of gas.”

The problem for the Apollo 14 crew’ was that the LM had settled with a 7” tilt that was enough to upset their sense of up and down in the dark, as Mitchell described after the flight: "We both had the feeling throughout the night that the blasted thing was trying to tip over on us. Actually, w’C got up and looked out the window a couple of times to see if our checkpoints w ere still right w’here they were supposed to be.”

Whereas the first three landings got away w’ith a single rest period on the Moon, it was NASA’s intention that the. І-mission crews w’ould stay on the surface for up to 72 hours. If a crew’ were to be expected to work at a high level of physical effort and mental concentration; to make a landing, spend three days on the surface and then guide their ascent stage to rendezvous with the CSM then, during three rest periods on the Moon, the suits w’ere going to have to come off.

To practise for this, Scott and Irwin even stayed a full night in the LM simulator in Florida starting w’ith a simulation of a landing. "We had it as high a fidelity as wn could possibly get it. So we had everybody put everything in the simulator down to the last detail.” He continued, "We got a terrible night’s sleep. I mean, boy, that’s crummy, trying to sleep in those hammocks in one g in that little thing. We did the suit doffing and everything. Of course, the suit doffing was such a pain, anyway, especially in one g. But it really paid off because, w’hen we got to the Moon we were very comfortable in doing that sort of thing.”

Doffing the suits made all the difference to sleeping in the LM. Crews found one – sixth-g to be very comfortable as they had enough weight to lie normally in the hammocks but not enough to cause pressure points. ‘‘I slept much better on the lunar surface than I did in orbit," remembered Jack Schmitt. "One-sixth gravity is a very pleasant sleeping environment with just enough pressure on your back in those hammocks to feel like you’re on something but not enough to ever get uncomfortable. 1 slept but my impression was that I only needed about five hours sleep to feel rested whereas ordinarily on Earth at that time I usually felt that I could use seven. But I think that’s related mainly to the lower gravity environment. You just don’t get physically as fatigued as you would on Earth. You get as fatigued mentally obviously you’re working just as hard with your neurons but physically you don’t work as hard.”