Space Station Leak Found, Fixed

Rommel writes "NewScientist.com is reporting that the cause of the leak in the International Space Station has been found and fixed. The leak was found in a hose in the Destiny lab module. The hose was used to equalize pressure and eliminate fog between two panes of a window. While the leak was so slow it was unlikely to pose a direct threat to the crew for months to come, some equipment on the ISS is only certified to operate above a certain air pressure. The leak was originally mentioned on Slashdot a few days back."

Comments

Re:pressure

[EvilTwinSkippy]

Actually the crew could work normally until about 1/2 of an atmosphere. If the change is gradual enough, your body build up extra red-blood cells to compensate. Mountain climber in the Himalayas actually park at camp for about six weeks to 'acclimatize' to the reduced atmosphere.

Most people would still need some bottled Oxygen to get up to the top of Everest though, at around 1/3 of an atmosphere. When the pressure gets that low, your body has trouble metabolizing fast enough to maintain temperature.

Putting some thought behind this

[becker]

With reduced pressure, the thermal capacity of the cooling air is proportionally reduced. Combined with changes in forced air flow and microgravity not creating convectional cooling, you can have long-term overheating issues with equipment that consumes very little power.

This is solved on satellites with conductive cold/hot plates, but that results in much heavier equipment.

Regarding leakage rates, it's very difficult to estimate leak flow rates. The flow might be proportional to pressure squared, or cubed. If it's in an elastic seal, it may completely re-seal when the pressure drops to a specific level.

Humans can function at elevations of about 5psi (see the other posts about mountain climbers), and survive on a little less. Since O2 is less than 20% of the atmosphere, you can theoretically live on 1psi of pure O2. But secondary effects are killers at that low pressure, such as keeping enough moisture in the lung tissue. When near-pure O2 is used, it is usually at about 3psi or nearly the partial pressure of O2 at sea level.

Re:pressure

[delcielo]

The truth is that above around 26,000 feet there is no amount of acclimatization that will compensate for the diminished oxygen/pressure. That's why they call it the "Dead Zone;" because essentially, you're dying. What happens is your cells start to deteriorate, becoming unable to contain fluids. Your brain starts to swell from the uncontrolled fluid buildup (High Altitude Cerebral Edema). Your lungs begin to do the same (High Altitude Pulmonary Edema). The only fix is oxygen and pressure.

When you get above around 30,000 feet, you start running into funny little things like needing the air/oxygen forced into you with positive pressure, rather than the kind of "on-demand" oxygen setups that are commonly used. If I remember correctly, this is related to pressure; but is not the same issue that you get with pressure higher up, where you're worried about the blood's ability to contain its nitrogen, and thus, about the blood boiling.

Scary stuff.