Mars is caked in patchy ice, say NASA scientists
Not a god awful small affair, scans show
Up to half the Martian surface could be covered with ice, according to the latest results released by NASA's Jet Propulsion Laboratory.
And thanks to new scanning techniques, scientists can say where the ice is with greater precision than ever before. This more detailed map should help NASA's Phoenix lander to work out where to dig when it arrives on the red planet in 2008.
Researchers working on data from the THEMIS (Thermal Emission Imaging System) instrument on board the Odyssey probe have discovered that the depth of ice deposits varies greatly, even over very short distances.
The team speculates that when Phoenix starts digging it could find hugely different depths of ice in trenches just a few feet apart.
The researchers concentrated on refining their knowledge of areas that have already been shown to have water ice present. These areas were identified by the gamma ray spectrometer on board the Odyssey orbiter, which is capable of resolving its scans down to the level of a few kilometres.
The new technique takes advantage of the fact that as the seasons change on Mars, dense, icy areas will retain heat for longer than loose surface soil. But taking thermal scans of the surface, and measuring how the temperature changes, the team can tell where the ice is to within a few hundred metres, and how deeply it is buried.
Joshua Bandfield, a research specialist at Arizona State University, Tempe, and author of the paper (published in the 3 May issue of Nature), says the type of ground also gives clues about the likely depth of ice. Surface rocks, for instance, will pump heat into the ground, meaning ice will only be stable at quite a depth. Dusty soil, by contrast, acts as an insulator so that ice will be stable much closer to the surface.
He told the BBC that the ice on Mars would likely cover a third to half of the planet's surface.
Philip Christensen of Arizona State University, Tempe, principal investigator for THEMIS, said: "Scientists have known for more than a decade that water is on Mars, mostly in the form of ice. What's exciting is finding out where the ice is in detail and how it got there. We've reached the next level of sophistication in our questions." ®
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