evp (11/17/82)
The suits run at 2.5 psi pure oxygen. This puts the partial pressure of oxygen at the same value as it is at sea level. The reason they run at such a low pressure is that the joints of the suit (especially at the fingers) are very difficult to move at higher pressures -- the internal pressure tends to straighten the joints out, and the astronaut has to fight against this force to hold onto tools, etc. The reason they don't want umbilical cords on the suits is fairly obvious: the first time you tried to grab a spinning satellite and got your oxygen supply wrapped up in the solar panels, you'd be out of a job. (A new definition of 'severance pay'). This is in fact a major part of the Solar Max rescue mission. The satellite is spinning at 1-2 rpm, and there is no way to stop it from spinning because the fuse that blew controls the stabilization mechanisms. The astronaut will cruise over to the satellite, grab onto it, then use the suit maneuvering system to stop the spinning. The Canada arm will then move it into the payload bay, where the fuses will be replaced.