These images produced by the Lyman Alpha Mapping Project (LAMP) aboard NASA's Lunar Reconnaissance Orbiter reveal features at the Moon's northern and southern poles in the regions that lie in perpetual darkness. They show many permanently shadowed regions, or PSRs, are darker at far-ultraviolet wavelengths (top inset) and redder than nearby surface areas that receive sunlight (bottom inset). The darker PSR regions are consistent with having large surface porosities — indicating "fluffy" soils — while the reddening is consistent with the presence of water frost on the surface.
Lyman Alpha Mapping Project
There are a whole lot of forbidding places in the solar system, but the permanently shadowed regions (PSRs) of the moon have to be near the top of the list. Found in the northern and southern lunar poles, the PSRs are low-lying spots — often deep in the bowls of craters — that never receive so much as a breath of warmth or a flicker of light from the sun. As a result, they don't go through the same heating and cooling cycle as the rest of the moon, where temperatures soar to 200°F during lunar daylight and plunge to –200°F at night. Instead, the PSRs remain in an unending deep freeze.
That ought to make those areas unlikely places for astronauts ever to visit, much less settle — except for one little wrinkle: if there happened to be water ice nearly anywhere on the surface of the moon, it would boil away the instant it felt the solar fires; at the poles it would last forever. In 2010, scientists discovered that even at lower latitudes, the moon is not entirely dry, with faint traces of ice surviving beneath the surface, making lunar soil about twice as wet as the sands of the Sahara — which by moon standards is practically drenched. Now, NASA's Lunar Reconnaissance Orbiter (LRO) has found that the PSRs indeed have a whole lot more water than that, with up to 2% of the surface in those blacked-out regions consisting of ice crystals.