Ice discovered on north pole of Mercury
Just in time for Christmas, scientists have confirmed a vast amount
of ice at the north pole - on Mercury, the closest planet to the sun.
The findings are from NASA's Mercury-orbiting probe, Messenger, and
the subject of three scientific papers released by the journal Science.
The frozen water is located in regions of Mercury's north pole that
always are in shadows, essentially impact craters. It is believed the
south pole harbours ice as well, though there are no hard data to
support it. Messenger orbits much closer to the north pole than the
south."If you add it all up, you have on the order of 100 billion to one
trillion metric tons of ice," said David Lawrence of the Applied Physics
Laboratory at Johns Hopkins University.
"The uncertainty on that number is just how deep it goes."
The ice is thought to be at least one and a half feet deep - and
possibly as much as 65 feet deep.
There is enough polar ice at Mercury, in fact, to bury an area the
size of Washington, DC, by two to two and a half miles deep, said Mr
Lawrence, the lead author of one of the papers.
"These are very exciting results," he said at a news conference.
For two decades, radar measurements taken from Earth have suggested
the presence of ice at Mercury's poles. Now scientists know for sure,
thanks to Messenger, the first spacecraft to orbit Mercury. The water
almost certainly came from impacting comets, or possibly asteroids. Ice
is found at the surface, as well as buried under a dark material.
Messenger was launched in 2004 and went into orbit one and a half
years ago around Mercury, where temperatures reach 426 degrees Celsius.
- AP
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