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| ||||| Wednesday, February 27, 2002 - 09:07 am |
Why is the pressure in the Shuttle cabin lowered from 14.7 to 10.2 psi during the main part of the mission? Is this a safety feature?
| ||||| Wednesday, February 27, 2002 - 07:45 pm |
I'm not sure. Try checking the Kennedy Space Center site, since Kennedy is where th shuttle is maintained
| ||||| Thursday, February 28, 2002 - 11:40 pm |
The Flight Surgeon would know for sure, but we think its related to lowering the astronaut's metabolic rate to reduce consumption of onboard oxygen supplies. Longer duration in space would be achieved.
| ||||| Friday, March 01, 2002 - 08:25 am |
What is the higest temp in the cabin
| ||||| Saturday, March 02, 2002 - 01:38 am |
A reference is made here to cabin pressures of 14.7 psi and 10.2 psi. Those equate to 100 kPa and 70 kPa, respectively.
Note the metric values are rational and the obsolete units are nasty looking.
| ||||| Saturday, March 02, 2002 - 11:00 am |
The cabin pressure is lowered from 100 kPa to 70 kPa to reduce the amount of nitrogen in the astronauts' bloodstreams. This reduces the chance that they might suffer from "the bends" when working outside the orbiter in their EVA suits, which also operate at this reduced pressure.
This has no effect on their metabolic rate that I know of. The human body responds to the absolute partial pressure of oxygen in the atmosphere, not the percentage. From my experience as a submariner (another case of a closed, managed atmosphere), I would guess that oxygen is added to this reduced atmosphere to maintain an oxygen pressure of approximately 20 kPa (of the 70 kPa total pressure) which is what the human body expects and is used to. Then the oxygen would constitute nearly 30% of the atmospheric pressure in the cabin with a corresponding drop in the nitrogen percentage.
J.R. Frysinger, CAMS
Dept. of Physics and Astronomy
College of Charleston
Charleston, SC 29424
| ||||| Saturday, March 02, 2002 - 05:49 pm |
On average how many hours sleep does the crew get
in a day?
| ||||| Saturday, March 02, 2002 - 06:20 pm |
The crew gets 8 hours to sleep.
| ||||| Saturday, March 02, 2002 - 11:49 pm |
That's 8 hours 0 minutes and 0 seconds between the "good-night" and the loud, raucous, obnoxious stuff that is called music that gets sent up to wake them up.
| ||||| Sunday, March 03, 2002 - 01:35 am |
Lest the metric police get after us for those last messages, 8 hours is 28.8 kiloseconds.
| ||||| Sunday, March 03, 2002 - 02:25 am |
Good correction on the nitrogen purge. Flight Surgeon explained it on the loop when the reduction was made.
It was only a matter of time until the Metric discussion started.
| ||||| Sunday, March 03, 2002 - 02:38 pm |
J.R. Frysinger, thank you for your comment -- it was very helpful. I hadn't thought about the fact that the EVA units need to work at a reduced pressure.