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This is a shame, but most people -- even in space programs -- don't appreciate how cold the Moon's shaded areas become. It's now estimated that these areas get
by lutusp 13y ago
This is a shame, but most people -- even in space programs -- don't appreciate how cold the Moon's shaded areas become. It's now estimated that these areas get to 26 Kelvins -- that's 26 degrees above absolute zero. To get a sense of how cold this is, Pluto's average surface temperature is seven degrees warmer.
Also consider that, because of the specifics of the Moon's orbit, a given area stays shaded for just over 14 days each month. That's a long time at a very low temperature. Unless a spacecraft has a way to heat itself during the long lunar night, its electronics will self-destruct.
- Scaevolus 13y agoDoes China have the capabilities and reserves of radioactive material to make probes with RTGs?
- sp332 13y agoIt has a radioisotope heating unit https://en.wikipedia.org/wiki/Yutu_%28rover%29#Specifications https://en.wikipedia.org/wiki/Yutu_%28rover%29#Specification...
- lutusp 13y agoOnline accounts say there's a radiation source for heating during the lunar night, but it seems one of the solar panels used for normal operations didn't fold up properly (by folding up these panels are closer to the heat source) before the sun went down, and that exposed component froze and was ruined, which sealed the spacecraft's fate. Source: http://www.dvice.com/2014-2-12/chinas-jade-rabbit-lunar-rover-freezes-death-moon http://www.dvice.com/2014-2-12/chinas-jade-rabbit-lunar-rove...
- TrainedMonkey 13y agoLooks like it: http://en.wikipedia.org/wiki/Timeline_of_the_Republic_of_China%27s_nuclear_program http://en.wikipedia.org/wiki/Timeline_of_the_Republic_of_Chi... They had capability to produce required material decades ago. They also have sufficient nuclear arsenal to warrant maintaining stockpiles of the stuff: http://en.wikipedia.org/wiki/China_and_weapons_of_mass_destruction#Nuclear_weapons http://en.wikipedia.org/wiki/China_and_weapons_of_mass_destr...
- seszett 13y agoYou are confusing the Republic of China, commonly called Taiwan (which is the subject of your first link) with the People's Republic of China, which sent this robot to the moon. Both of them have nuclear power though (but only PRC has nuclear weapons) and radioactive material in sufficient quantities.
- sgrove 13y ago> Pluto's average surface temperature is seven degrees warmer. What about the temperature in Pluto's shaded regions (if there are any)?
- exhilaration 13y agoMaybe Pluto's atmosphere keeps the temperature warmer? I assume it's too far from the sun to have any unshaded versus shaded regions.
- sp332 13y agoThe average "temperature" of empty space is 3K, due to heating by background radiation. That's a big enough difference to have a warmer sun-facing side and a cold, shaded side.
- oftenwrong 13y ago>To get a sense of how cold this is, Pluto's average surface temperature is seven degrees warmer. That doesn't give me a good sense because I have no idea how Pluto's average surface temperature compares to typical on-Earth temperatures that I have experienced. This gives me a better sense: 26 K = -247.2 C
- shitgoose 13y agoIs that with the windchill?
- deleted 13y ago[deleted]
- officemonkey 13y agoNo atmosphere, therefore no wind, thus no windchill.
- akfanta 13y agoYou must be fun at parties.
- comex 13y agoOr -413 F for us silly Americans.
- fallinghawks 13y agoOh, so something like Canadian winter. ;)
- lutusp 13y agoIMHO you're better off thinking in Kelvins. Room temperature is 295 Kelvins, the cosmic background radiation (the leftover glow of the Big Bang) is 2.7 Kelvins, and between the stars, far from any particular star, an object naturally cools to the universe's background temperature of 2.7 Kelvins.
- Buttons840 13y agoFun bit of trivia: If a moon rover could maintain speed of about 11 miles per hour (17 Kilometers per hour) forever, it could circle the moon in 28 days, and would be moving fast enough to stay on the light side of the moon. That doesn't seem very fast, but with the moons low gravity and all.... You'd have to be doing science while catching big air.
- Pxtl 13y agoThat said, temperature works differently in hard vacuum - with no air to conduct/convect the heat away, isolated objects don't actually get "cold" the way they would in a pool of liquid nitrogen or something. Notice you don't hear about the ISS freezing at night.
- unspecified 13y agoThe 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.
- 1morewebdev 13y agoSuppose China were to send another Rover up in the next 5 years, and it found this one. In theory, could this one be repaired? Or will the "electronics self-destruct" be thorough by then?
- sounds 13y agoSome assumptions I have to make are: • The RTG in Yutu (the rover already up) will last that long • Yutu does not move, get struck by a meteor, or other normal events in space that will damage it further • The team who understands Yutu is still around in 5 years Then China could, in theory: • Assemble a rover with the repair parts on board • Launch it to the moon • Land on the moon intact • Locate Yutu • Do a remotely-operated repair There's a lot of risk in each of those steps. It might be an interesting mission to push the boundaries of tele-operated robotics etc. Realistically it seems less expensive to launch a second rover that has been improved based on the lessons learned from Yutu. Hopefully China can think of lots of things to improve the second time. Interesting thought experiment, though.