Daytime on Mercury’s equator can break the 800-degree mark, but nonetheless there’s long been speculation that the first planet’s poles might be icy. A new analysis of neutron-spectrometry data returned by the Messenger probe confirms the hypothesis: there’s ice in some polar craters!
When radar detected brightness near Mercury’s poles in 1992, the prevailing theory and hope was that it was H2O, but there are other reflective substances it might have been: lovely white sand deserts, perhaps.
Messenger, the NASA probe that’s been orbiting Mercury for a couple of years now, analyzed neutrons coming from the planet, and noticed that the quantity was lower above the polar bright spots — exactly commensurate with the way water ice absorbs neutrons.
Time to build a Mercury colony.