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General Discussion => Q&A Section => Topic started by: mako88sb on 10/17/2019 03:41 pm

Title: Emergency donning of Spacesuits
Post by: mako88sb on 10/17/2019 03:41 pm

One article says that the Apollo astronauts were trained to put their spacesuits on in 5 minutes by themselves in case of an emergency. Makes sense but training while in a 1 G environment is one thing, how long would it actually take in zero G? I didn't think it would be possible to train for this in the vomit comet but I guess they could time it during the weightless intervals? Is the same standard still expected of astronauts today?

Title: Re: Emergency donning of Spacesuits
Post by: joema on 10/17/2019 07:23 pm

Quote from: mako88sb on 10/17/2019 03:41 pm

...Is the same standard still expected of astronauts today?..

The main issue is today cabin environments are N2/O2, typically at about 14 psi. The suits use about 4.3 psi pure O2. This raises the question of whether rapid donning of a space suit has any purpose since the astronaut would suffer decompression sickness (the bends).

In the shuttle/ISS era, I think the normal pre-breath protocol prior to donning a suit for EVA was about 12 hours, although in a contingency they might do four hours pure O2. The absolute minimum in a dire contingency is 2.5 hours pre-breath of pure O2. Scott Manley did a recent video about shuttle contingency EVAs which mentioned this: https://youtu.be/qOb5tdtHIG4

The Apollo cabin environment was about 4.8 psi pure O2. The suits used pure O2 at about 3.7 psi, although this was adjustable. I vaguely recollect the CM/LM environmental control system had an emergency capability to maintain about 3.5 psi cabin pressure for a few minutes following hull rupture a few inches in diameter. With pure O2 there was never any risk of decompression sickness, so rapid donning of suits would hypothetically help.

I think during all critical flight phases Apollo astronauts wore suits, sometimes not pressurized or without gloves. They could don gloves and/or pressurize the suits quickly.

Title: Re: Emergency donning of Spacesuits
Post by: mako88sb on 10/18/2019 05:27 pm

Thanks for the info. Should have figured out myself about the difference between the Apollo environment and the shuttle/ISS would answer my last question. Interesting video, thanks for the link.