In article ,
says...

On 2019-05-21 22:21, Greg (Strider) Moore wrote:

Why would LEM-2 need to operate at 1ATM since it will never operate on
earth?


For the same reason ISS operates at 1 ATM. It makes some parts of the
operations easier.

Ah so this 1 ATTM was meant as cabin pressure. When I read it, I was
thinking about engines for sea level vs vacuum, hence my questioning
requiremenet to operate a LEM at 1 ATM.

If the cabin moves from 5PSI to 14.7, does that change much in terms of
thickness of walls/windows needed ? Or is the change fairly minimal?

Cabin pressure. The US has used standard sea level pressure and N2/O2
mixture since the space shuttle. The Russians have used that standard
from the very beginning.

The pure O2 atmospheres in early NASA spacecraft simply isn't acceptable
to the medical people for long term spaceflights. It was a kludge early
on so US spacecraft could be made lighter. I doubt any future US
spacecraft, aside from EVA suits, will use that kludge again.

Jeff
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