Hatch Closing - Thermal Constraints
On all the missions, the LMP closed the hatch on his way out. The following example is from Apollo 11.
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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.
109:41:53 Armstrong: (Laughs) A particularly good thought.
[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. Neither Neil or Buzz remembered any specific reason.]
Journal Contributor Harald Kucharek found the following in the Apollo 11 Lunar Surface Operations Plan, on p.171.
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5.3.4 Lunar Surface Operations Constraints
LM Forward (+Z) Hatch operations:
The forward hatch may be left fully open during the EVA (up to 3 hours)
provided: (CRITICAL) (GAEC LM Engineering Memorandum LMO-510-1201,
April 24, 1969)
1) The cabin temperature, GF 1641T, must be between 60F and 90F at the beginning of the EVA, andOtherwise, the limit is:2) The sun vector is outside a 65 degree cone about the +Z axis.
1) 15 minutes for hatch fully open or------ Harald and I are not clear about the geometrical meaning of "sun vector is outside a 65 degree cone about the +Z axis". For me, this translates to "the sun should not be able to shine through the hatch", which would mean that radiative heating of the cabin had to be prevented, not cooling. Another possibility is to prevent backscattered light entering the cabin, but why?2) For the duration of the EVA provided the door is no more than 3 inches from the closed position, using the door snubber device for control.