NASA: Water Ice Confirmed on Mercury's Polar Craters
Posted on November 29, 2012
NASA says observations by the Messenger spacecraft have confirmed water ice on Mercury's permanently shadowed polar craters. The ice survives on the planet closest to the Sun because there are pockets at Mercury's poles that are never exposed to sunlight. The scientists say this is due to the tilt of Mercury's rotational axis being almost zero. The image above shows in red the areas of Mercury's north polar region that are in shadow. The polar deposits imaged by Earth-based radar are in yellow. You can see a larger version of the image here.
NASA says in a release that Messenger images from 2011 confirmed that bright spots at Mercury's poles lie within shadowed regions on the planet's surface. NASA says this data is consistent with a water ice hyptothesis. The water ice is exposed at the surface in some of Mercury's north polar deposits, but is buried beneath a thin layer of dark material in most of the deposits.
David Lawrence, a Messenger participating scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., said in the release, "We estimate from our neutron measurements the water ice lies beneath a layer that has much less hydrogen. The surface layer is between 10 and 20 centimeters [4-8 inches] thick."
The full 50+ minute press briefing is below. Dr. Sean Solomon, principal investigator for the Messenger Mercury mission, begins explaining the findings at the 3:30 mark: