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In the transcript of the Apollo 11 EVA on the Moon, Buzz Aldrin mentions closing the LM's hatch and being careful not to lock the two astronauts out.

109:41:28 Aldrin: Okay. Now I want to back up and partially close the hatch. (Long Pause) Making sure not to lock it on my way out.

(see https://www.hq.nasa.gov/alsj/a11/a11.step.html)

Why bother closing it at all, why not just leave it open?

Bonus question: Could they have actually locked themselves out?

user
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    I like your bonus question. I imagine "Houston... we've had a problem here. We just locked ourselves out" – Manu H Jul 25 '19 at 11:33
  • @ManuH honestly that would be have been the scariest part of the mission for me. I could handle dying in some heroic accident trying to land, but locking myself out of the LM would have been too embarrassing. – user Jul 25 '19 at 13:26
  • My guess is so that intense heat or more radiation (radiation still entered the LM) doesn't go into the cabin and damaging electronics. – Star Man Jul 25 '19 at 14:13
  • The EVA hatch and the depress valve could be operated from either side of the hatch. Aldrin was essaying a jest. – Organic Marble Jul 25 '19 at 14:33
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    Keeping dust out maybe? – Steve Linton Jul 25 '19 at 14:33
  • I don't have time to read this and give a good answer but there's probably something in here that will help: https://www.hq.nasa.gov/alsj/LM04_Lunar_Module_ppLV1-17.pdf – Seth Kurkowski Jul 25 '19 at 15:37
  • The link I provided speculates that it was to reduce heat loss from the LM, but given that it was in a near vacuum I'm not sure that really makes sense. – user Jul 25 '19 at 15:59
  • @SteveLinton maybe, but it was high up so not much opportunity for dust to get in. I suppose they didn't know that at the time though. – user Jul 25 '19 at 16:00
  • @SteveLinton Maybe on Earth the dust can get in because of the atmosphere and wind but not on the moon as there's no atmosphere. The only way dust could get in if someone kicks it, and etc. Plus lunar regolith was stuck on their suits and entered the LM. – Star Man Jul 25 '19 at 16:13
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    Because their mothers trained them well. – PJNoes Jul 25 '19 at 16:44
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    Dust was certainly known to be a problem from the Surveyor missions. That's why they were given the Equipment Transfer Bag, to keep the replacement LiOH canisters clean when transferring them from the drawer in the descent stage to the cabin. https://i.stack.imgur.com/mKBaN.png But I don't know about the reason to close the hatch, probably also dust. – DrSheldon Jul 25 '19 at 18:31

1 Answers1

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The answer is in the link you provided in your question. Here.

The reason they closed the hatch was so that the interior of the LM won't cool down.

The hatch can be opened from the outside, if necessary. The reason for almost closing the hatch is, I believe, to prevent radiative cooling of the cabin

If they allowed it to cool down, it would require more energy to heat it back up to an appropriate temperature.

Star Man
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