Ed Davies on Nostr: You can but then to get enough oxygen you have to have a pure oxygen environment (as ...
You can but then to get enough oxygen you have to have a pure oxygen environment (as they have inside the spacesuits). That's a problem as they found in the Apollo 1 fire [¹]. The Apollo spacecraft (both the command module and the lunar module) had a 5 psi pure oxygen atmosphere from shortly after launch (it depressurised from sea-level pressure during the ascent).
That's why the Apollo astronauts walked out of the crew building with their helmets on carrying that box - not their lunch but an oxygen supply (or rebreather????) - so they'd purge nitrogen on they way.
Michael Collins (Apollo 11 command module pilot) had some problems with joint pain during the ascent of his Gemini launch (which used the same system) so was careful to make sure he was zipped up as soon as possible for his Apollo launch to avoid that.
The Shuttle, Mir,, ISS and Soyuz all use(d) an oxygen/nitrogen mixture at more normal sea-level pressures so don't have this problem at launch but do need the pre-breath before EVAs.
[¹] https://en.wikipedia.org/wiki/Apollo_1
[@ZachWeinersmith](https://mastodon.social/@ZachWeinersmith)
That's why the Apollo astronauts walked out of the crew building with their helmets on carrying that box - not their lunch but an oxygen supply (or rebreather????) - so they'd purge nitrogen on they way.
Michael Collins (Apollo 11 command module pilot) had some problems with joint pain during the ascent of his Gemini launch (which used the same system) so was careful to make sure he was zipped up as soon as possible for his Apollo launch to avoid that.
The Shuttle, Mir,, ISS and Soyuz all use(d) an oxygen/nitrogen mixture at more normal sea-level pressures so don't have this problem at launch but do need the pre-breath before EVAs.
[¹] https://en.wikipedia.org/wiki/Apollo_1
[@ZachWeinersmith](https://mastodon.social/@ZachWeinersmith)