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?

  • 2
    $\begingroup$ I like your bonus question. I imagine "Houston... we've had a problem here. We just locked ourselves out" $\endgroup$
    – Manu H
    Commented Jul 25, 2019 at 11:33
  • $\begingroup$ @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. $\endgroup$
    – user
    Commented Jul 25, 2019 at 13:26
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    $\begingroup$ Keeping dust out maybe? $\endgroup$ Commented Jul 25, 2019 at 14:33
  • 4
    $\begingroup$ Because their mothers trained them well. $\endgroup$
    – PJNoes
    Commented Jul 25, 2019 at 16:44
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    $\begingroup$ 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. i.sstatic.net/mKBaN.png But I don't know about the reason to close the hatch, probably also dust. $\endgroup$
    – DrSheldon
    Commented Jul 25, 2019 at 18:31

1 Answer 1


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.


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