Innermost planet Mercury
would probably not be a good location for an
interplanetary winter olympics.
But new results based on data from the
MESSENGER spacecraft indicate that
it does have substantial water ice
in permanently shadowed regions within
craters near its north pole.
The possibility of ice on Mercury has been entertained for
years, inspired by the discovery of radar bright, hence
highly reflective, regions near the north pole.
yellow in this map based on projected
radar bright regions are seen to correspond
with floors and walls of north polar impact craters.
Farther from the pole the regions are concentrated
on the north facing crater walls.
thermal models for the
craters indicate material in these regions has a hydrogen content
consistent with nearly pure water ice and is
trapped in an area with temperatures that remain below
(-280 deg.F, -173 deg.C).
In circumstances similar to permanent shadows in craters
of the Moon,
debris from comet impacts is thought to be the source of
ice on Mercury.
JHU Applied Physics Lab /
Carnegie Inst. Washington