Originally Posted by
wiggy
AFAIK the idea is to launch with the cabin ventilated with air at 1 bar but certainly on missions where there is going to be an EVA (see edit) it would then gradually to morph to (?) About 2/3 of a bar but oxygen rich (30% 02).
The thinking behind that is that is to reduce the time spent pre breathing with 02 prior to EVAs, where you need to be at low pressure but high 02 to keep the suits flexible..
I think I read somewhere that there is one thing that you cannot do in a space suit............ whistle.
At EVA pressure, there are insufficient O2 molecules for you to make that sound. I have no idea who discovered this or why they attemted to whistle in the first place.