Subsurface ice on Mars exposed by recent impact craters

March 31st, 2009 - 12:50 pm ICT by ANI  

London, March 31 (ANI): The HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter (MRO) has observed some small, freshly gouged craters in images taken in 2008, which in turn have exposed hidden subsurface ice on the Red Planet.

According to a report in New Scientist, seen at five sites over a latitude range of 43 degrees to 56 degrees north, the excavations are typically 3 to 6 meters across and a third to two-thirds of a meter deep.

One cluster must have appeared sometime between June and August, and a somewhat larger pit showed up between January and September.

What did astound the team were splashes of white seen in and around a handful of these craterlets.

Apparently, fist-sized impactors had punched into a layer of ice hidden by a topping of dust about a third of a metre deep.

In the months that followed, these snowy splashes gradually faded from view.

Water ice isn’t stable at the craters’ latitudes, so most likely, it gradually sublimated, or vaporised, into the atmosphere, leaving behind a veneer of any dust that had been mixed with it.

The disappearing act might also be due in part to a coating of dust blown in from the atmosphere.

Either way, notes HiRISE investigator Shane Byrne of the University of Arizona, the icy deposits had to be at least a couple of inches (several centimeters) thick, and they couldn’t have been unearthed from more than a foot or two (0.3-0.6 m) down.

According to Byrne, prior surveys, particularly one done by the neutron spectrometer aboard NASA’s Mars Odyssey orbiter, show that vast reservoirs of ice lay barely buried across most of the planet’s polar and mid-latitude regions.

But, scientists are only now realising just how near the surface the ice lies - and how easily it can be reached.

“It’s probably just tens of centimeters down,” said HiRISE team leader Alfred McEwen. (ANI)

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