
If you're doing large-scale satellite servicing, being able to do it in
a pressurized hangar makes considerable sense.  The question is whether
anyone is going to be doing large-scale satellite servicing in the near
future, to the point of justifying development of such a thing.


You'd almost certainly use air.  Given that you have to pressurize with
*something*, safety considerations strongly suggest making it breathable
(even if the servicing crew is using oxygen masks for normal breathing,
to avoid needing a ventilation system, it's nice if the hangar atmosphere
is breathable in a pinch -- it makes mask functioning much less critical).