Space/Science — HabitableZone

Space/Science » in reply to re: Why the heck would you want to dive down a gravity well in the first place?

re: Why the heck would you want to dive down a gravity well in the first place?
gbaikie — (archived)

"That chamber has been built, and it will soon be at work in the basement of the LD building here at IUPUI. In that chamber, the pressure will be less than 10 -6 Pa, or about 10 -11 atmospheres, since atmospheric pressure is about 10 5 Pa (recall that a "Pascal" is a N/m2).

This is a pretty good vacuum, about 10 to fifty times better than the vacuum in space at the typical orbit of the space shuttle (a few hundred km elevation). However, it is by no means the best vacuum that can be achieved. Vacuum scientists often categorize vacuum according to this scheme
Vacuum Category Pressure (Pa)

Rough Vacuum 100 - 10 5
Medium Vacuum 10-3-100
High Vacuum 10-6-10-3
Ultra-High Vacuum less than 10-6

The best vacuums available on Earth are less than 10 -8 Pa, less than 10-13 atmospheres!"
http://webphysics.iupui.edu/251/251Fall96TWNov11.html
[note number are expressed in exponents and these don't copy- see web sites] And 1 atm = 101,325 Pascals = 760 mm Hg = 760 torr = 14.7 psi.

So, Mars has 10 times more atmosphere than a medium vacuum or could be called a rough vacuum. And would guess that the Moon has ultra-high vacuum, though suppose it could be only high vacuum. Since it say the best vaccuums on earth are 10e-8 Pa, the question is are there places on the Moon where there is this level of vacuum.
Another aspect is that suppose the best vacuum on the Moon is between 10e-6 and 10e-3 [high vacuum]. There is the advantage of having a large area to do this in. Also one could still have fairly large areas and do things to improve the vaccum. In other words you get a space which is the size of aircraft hanger on the Moon and improve the vacuum slightly- say purge it with microwave energy or heat [infrared radiation].

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