"Henry Spencer" wrote:
In article ,
Harmon Everett wrote:
I've been wondering about an airlock plus large plastic ziploc baggy
arrangement for minimizing air loss.

As Chris has already noted, it's hard to make this work when you look
at the details.

What you can do is to have close-fitting airlocks for things which come
in reasonably standard sizes -- notably people -- to minimize empty volume
in the airlock.

Something like an iron maiden, that out to work reasonable
well. The problem with the membranes is that they're either
horribly complicated or only solve some of the problems.
Plus, the vacuum sealed bag idea doesn't solve the problem
at all, as the whole purpose is to save the air and if you
can pump the air out of a flexible bag you can certainly
pump it out of a similarly sized rigid container. With the
added benefit that the rigid container of the same volume
won't act as a remarkably effective restraint device. In
other words, you really need a much "smarter" and more
sophisticated membrane than just a flexible bag, or even a
baloon. Now that I think about it, you'd really need
something approximating an animal gut (able to close tightly
around an object but also release it).

The way I look at it, I think there are a variety of
different techniques that can be layered together to
minimize air loss. Each technique will have its own degree
of cost/benefit so I'd expect that at some point you end up
with enough stuff together that works reasonable well at a
given cost.

The biggest problems I see with the docking spacesuit is that
it makes routine maintenance harder, since the suit is
outside most of the time, and it decreases flexibility a
lot. In other words, it creates more of a firm disconnect
between inside and outside, and that can have a lot of
disadvantages.

I really like the sorption pump concept because it's
relatively simple, should work well in space (where cold is
always available fairly easily), and should recover most
of the air in the airlock.


Another thing to think about would be separate airlocks for
crew and for equipment, such that the equipment airlock could
use more "uncomfortable" and perhaps less timely methods of
air recovery. For example, with an equipment airlock it
doesn't much matter if it takes hours for it to operate.