Oceans of ice lie just beneath surface of Mars
If colonists on Mars want to chill their gin and tonics, they won’t have to dig far.
Satellite imaging has confirmed that vast glaciers of ice exist just a metre below the surface, and continue to a depth of a hundred metres or more below that.
The findings provide the clearest picture yet of the water locked up on Mars, a remnant of its beginnings as a watery world.
Knowing more about Mars’s ice deposits is crucial to planning a visit and eventually building a permanent base. Not only is water
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useful for drinking and growing crops, it can be converted into rocket fuel, meaning that spacecraft would not have to take enough for a return trip.
More immediately, mapping ice deposits is useful in working out the history of the planet’s climate.
Although it is no surprise that Mars contains sub-surface ice, the latest satellite surveys were the first to look at specific sites in detail.
Nasa’s Mars Reconnaissance Orbiter, which has been studying the planet since 2006, used radar and other instruments to look at eight areas with prominent escarpments. These sudden cliff faces are caused by the retreat of sub-surface glaciers, leaving the ice beneath partially exposed. They allow the glacier to be studied in detail, meaning that researchers could work out how deep the ice went and also how much dust lay on top.
They argued that the accessibility of the ice, which often lay just beneath the surface, made it a goal for future missions.
‘‘This ice is a critical target for science and exploration: it affects modern geomorphology, is expected to preserve a record of climate history, influences the planet’s habitability, and may be a potential resource for future exploration,’’ they wrote.
By looking at the frequency with which boulders on the edge of the escarpment tumbled on to the debris below, the researchers, who published their findings in the journal Science, were able to estimate that the glaciers retreated at a rate of about a millimetre a year.
Just as ice cores on Earth provide a record of past climatic events, the glaciers could tell us about the Martian atmosphere at the time they were formed.
It is believed that at its formation four billion years ago, Mars was a watery planet similar to Earth, with large portions of its surface covered in ocean.
The glaciers were probably formed by snowfall only a few million years ago, possibly during a tilt in the planet’s axis. The snow would have then been compacted into ice, much like glaciers on Earth. – The Times