Liquid Oxygen Questions

From: "victoriatangoman"
To:
Sent: Wednesday, March 13, 2002 3:45 PM
Subject: [spacesettlers] Liquid Oxygen Questions

[snikt]
> First, if we assume an atmospheric pressure, could be anything, but
> let's work with 1 atmosphere. The effect of this atmospheric
> pressure would be to exert a force of 15 lbs/in2 against the
> pressure vessel. Now how does the radius of the cylinderical habitat
> effect the total mass of the atmospheric gases? The way I see it,
> the mass of the gases is directly proportional to the area of the
> pressure vessel and the height has no effect. If this is true, is
> there anyone in this group who can address the question of at what
> height would the atmosphere be so thin as to not be life sustaining?
> I would think that the majority of the atmospheric mass would be
> concentrated at the highest gravity gradient. Is that correct? Or
> could it be that the gases, while still maintaining the same 15
> lb/in2 density are more evenly distributed and therefore, would be
> thinner that what we would expect on the living surface but thicker
> at higher altitudes?
[snikt]

I am a nullity in fluid dynamics, atmospheric flow and related stuff, but my
gut feeling is that, for a habitat the size you're proposing (a radius of
0.5 Km) there will be no noticeable change in atmospheric pressure in any
point of the internal surface of the habitat. On Earth, the "pressure
habitability level" is much higher than that radius, it is something like 3
or 4 Km of altitude (and that explains why there are millions of people
living in the Andes and the Himalayas). But the gravitational field of Earth
is nearly uniform as far as the atmosphere is concerned, while the "field"
in a habitat gets weaker very quickly as "altitude" (proximity to the axis)
increases. So, my gut feeling is that the atmosphere inside a habitat will
get thinner more slowly with altitude compared with the same rate for the
atmosphere of Earth - for the air gets lighter quickly and puts less
compression in the layers below. Therefore, I think that the "pressure
habitability level" in a (very big) habitat is considerably higher than on
Earth.

But those are just "gut feelings", intuitive notions that may be wrong. I
also would like to see the opinion of someone who really understands the
subject...

Lucio Coelho