David.Smith@CMU-CS-A@sri-unix (11/22/82)
From: David.Smith at CMU-CS-A (C410DS30)
I see that my statement about boiling blood has been defended better than
I could have myself. But let me point out that boiling has to do with the
fluid's vapor pressure matching the ambient gas pressure. You can boil
water either by raising its vapor pressure (by heating it),
or by reducing the required vapor pressure (by lowering the ambient gas
pressure).
Back in the early '60s, National Geographic ran an article called
"The Long, Lonely Leap." It was about a fellow named Kittinger who
tested a new high-altitude parachute system by jumping from a balloon
at 102,000 ft. As he jumped, or just before, one of his gloves lost
pressure. He landed with a hand painfully swollen to the point of
unusability. I think it took something like four hours for his hand
to recover.
Here are some standard atmospheric pressures taken from the Handbook of
Chemistry and Physics. (Sea level pressure is > 1000 millibar because
the assumed sea level temperature is the pilot's 59F standard.)
Altitude Pressure
Meters Feet millibars psi
-------------------------------
0 0 1013.25 14.84
11000 36089 226.32 3.315
20000 65617 54.748 .802
32000 104987 8.678 .127
47000 154200 1.204 .0176
75000 246062 .0245 3.59e-4
This shows that the 60000 or 63000 foot level provides considerably less
pressure than is in the astronauts' suits, even with Lenoir's down to
3.7 psi.
If we use this sea-level pressure and the 21% oxygen figure, we get an
oxygen partial-pressure of 3.1 psi. So the astronauts are running a bit
rich. Maybe they could use 3.1 psi of O2, plus another pound of N2, if
they want the suits over 4 psi. On the other hand, maybe they need the oxygen.
During Gemini, astronauts tended to fog up their face plates while trying
to do real work.
David Smith