This answer seems to indicate the air-lock pressurization/de-pressurization is a drawn out process. Pressurisation is said to consume 45minutes (somewhat less in case of an emergency). Depressurisation may be a tad quicker. In case of both there almost certainly are check-lists, and protocol to follow.

What I'm curious about

  • How long does depressurization of the Quest Joint Air-lock take?
  • Apart from check-lists, what do the astronaut/s do whilst the air-lock cycles?
  • 6
    $\begingroup$ Tell rude jokes, with the comm off. $\endgroup$
    – geoffc
    Commented Dec 30, 2013 at 23:11
  • 1
    $\begingroup$ I would think that would be a great time to go over the spacewalk plan as many times as possible, and try to memorize it. $\endgroup$
    – this
    Commented Dec 31, 2013 at 12:15
  • 2
    $\begingroup$ I would spend the time OCD-checking my suit over-and-over, among other duties. $\endgroup$
    – Mikey
    Commented Mar 2, 2017 at 23:20
  • $\begingroup$ Sudoku, probably. $\endgroup$
    – Vikki
    Commented Oct 3, 2019 at 1:15

2 Answers 2


I think the "apart from checklists" caveat in your question makes it difficult to give you the answer you want. Astronauts aboard the ISS have a checklist that they have to complete for basically every mission activity (here is the NASA checklist for EVA), especially if its related to the outside of the bulkhead.

Page 54 of that document makes it seem as though crewlock repressurization is designed to take approximately 15 minutes- 5 for prep, 10 for the actual repress process, and then I'm sure there are plenty of time consuming activities during the Post-EVA process.

If you feel like skimming through the rest of the EVA manual, you might note that some airlock pressurization criteria are things like "Wait until |dP/dT| < 0.04 mmHg/min" or "Wait 25 seconds." This leads me to believe that there are some opportunities for conversational chatter/dirty jokes with the comm officer, but it probably depends on who's in the airlock (and on the other end). Besides, there is a lot to be focused on when you're running through these mission procedures, so I doubt ISS astronauts are bored in there. They do have to record instrument readings and do maintenance checks.

I know if it were me, I'd be far too transfixed by the upcoming (or recently completed) space walk to talk a lot about the weather down below, meal plans, or family, but hey...people can get used to anything. I'm sure to some of the more experienced spacewalkers, it becomes routine.

  • $\begingroup$ While repressurization is fairly quick, preparation for depressurization - preparation for donning the equipment and the prebreathing exercise - take 110 minutes. In particular, there's at least 11 minutes spent on rather boring, repetitive physical exercise. $\endgroup$
    – SF.
    Commented Mar 2, 2017 at 0:06

The current EVA procedure involves the astronauts camping out for several hours in the equipment lock while pressure the air transitions from the standard for the station to what they will be breathing in the suits.

During this time, they do all kinds of things. They eat and drink. They perform light exercise to accelerate the removal of nitrogen from their bloodstreams. They take naps.

The amount of time they spend doing this procedure varies quite a bit. See page 80:

  • 1
    $\begingroup$ The question is about depress/repress time, not the campout. $\endgroup$ Commented Mar 1, 2017 at 23:11
  • $\begingroup$ The depress time is determined by the procedure $\endgroup$ Commented Mar 1, 2017 at 23:45

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