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The ISS is only in shade for 45 minutes at a time, which is orders of magnitude less than a lunar night. But speaking of that: how long is too long to spend at
by unspecified 13y ago
The ISS is only in shade for 45 minutes at a time, which is orders of magnitude less than a lunar night.
But speaking of that: how long is too long to spend at 26K in a vacuum? Are there any good articles/videos that talk about what happens to various materials at such extreme temperatures in a vacuum?
- mpyne 13y agoI think the point of the parent comment was that simply being in a cold vacuum doesn't make you instantly cold. That still requires a process of heat transfer, which occurs in a fluid via conduction, convection, and radiation. When immersed in a vacuum the conduction and convection heat transfer paths are sharply reduced, so the question then becomes how fast do you cool off via radiation alone? I'm not a physicist so I don't know, but it's certainly nowhere near as fast as conduction/convection (in fact I believe heat dissipation was actually problematic for many spacecraft designs).
- lutusp 13y agoAs it turns out, even on earth's surface, radiation is a more efficient heat transfer method than conduction and convection through the air. Objects under a clear sky quickly drop below air temperature in many circumstances.
- hrkristian 13y agoThank you! I did an hour jog tonight, and most of that time was spent trying to figure out why there was frost on the ground with an air temperature above freezing and a warm breeze.
- dTal 13y agoI wonder if heat might also be conducting downwards to the frozen ground below.
- grogenaut 13y agoWhat he's trying to say is that if you toss a rock into liquid helium or a 4 Kelvin zero g vacuum it's going to get colder faster via direct contact with the helium than via radiation in the vacuum.
- mpyne 13y agoWow, that seems amazing but now that you mention it I think I've heard of that happening even in deserts.