Close to the Sun

Interesting news from Mercury, courtesy of MESSENGER. Results roll in and science fiction authors celebrate the (re)birth of a setting.

The temperatures right at the surface in these dark spots are actually too hot for water ice to be stable at the surface. However, dig 10 or 20 centimeters down, and you get to a region where the temperature is around 100 Kelvin, and ice is stable. The conclusion from all of this: the permanently shadowed craters do contain water ice, but it's not right at the surface; it's sequestered about 10 or 20 centimeters below the surface. What's at the surface, then? It's some dark material that is stable at 170 Kelvin. There are several different things this could be, but Dave said they were favoring the hypothesis that the dark stuff is complex organic compounds like those found in carbonaceous chondrite meteorites. These compounds would be volatile elsewhere on Mercury—that is, they're not stable as solids, but rather as gases—but would get trapped in cold, permanently shadowed areas just the same way that water ice would, at rather higher temperatures. So: there's water ice at Mercury's poles, capped with a layer of carbon-rich material. Dave pointed out that this makes the permanently shadowed areas near Mercury's poles surprisingly habitable. Dig a very short distance below the surface and you have comfortable temperatures as well as access to water and organic material.

Get plotting, folks!