Originally posted by Schumi
What the hell is a torr?

You know, when a girl slips and her shoe gets caught in her slip you say it was torr🙂
Seriously, its a pressure defined as 1/760th of an atmosphere, 760torr =14.7 PSI so one torr=about 0.02 PSI. The atmosphere on mars comes in at about 0.15 PSI so its about 7-8 Torr. Interesting pressure range, that is roughly the range of pressure used in some semiconductor operations. Some devices want as close to outer space as we can get, but we can't get within 4 orders of magnitude of the vacuum in outer space with regular cleanroom vacuum pumps but some machines need pressures on the order of 1 to 10 Torr to operate, like those machines that produce etching plasmas for instance. So it looks like those machines might be used right on the surface of mars, just open the door to the air on mars and start running! At least if you want a carbon dioxide carrier gas. (Carrier gas is the main constituent of a plasma, but you add other kinds to do the precise job you want. Argon is the main carrier gas normally, so you might use a mixture of Argon and Oxygen, a potent etching beam)
The official definition of one Torr is the pressure exerted on 1mm of mercury, that is to say, one torr will lift a thin column of mercury up one millimeter, which happens to be 1/760th of regular atmopshere. The Torr unit was named after an Italian physicist from the 1600's named Torricelli, who, among other things, invented the barometer.