Salt indicates life on Mars
2008-03-21 08:48
Washington - US scientists have discovered salt deposits on the surface of Mars, indicating that water was once plenty and pointing out sites that could provide evidence of past life, a study said on Thursday.
The deposits were discovered by a team of scientists led by Mikki Osterloo at the University of Hawaii using thermal images from the orbiting Mars Odyssey spacecraft, according to research in the March 21 issue of US journal Science.
The researchers have discovered some 200 separate salt deposits in the southern hemisphere of Mars and at mid- to low-level latitudes at terrain the scientists described as ancient and heavily cratered.
"Many of the deposits lie in basins with channels leading into them," said journal co-author Philip Christensen from the University of Arizona.
"This is the kind of feature, like salt-pan deposits on Earth, that's consistent with water flowing in over a long time," he added.
According to Osterloo, the deposits "range in area from about one square kilometre to about 25 square kilometres."
The deposits appear to be disconnected, so "we don't think they all came from one big, global body of surface water," she said.
Instead "they could come from groundwater reaching the surface in low spots. The water would evaporate and leave mineral deposits, which build up over years," she said.
The scientists estimate that these deposits were probably formed between 3.9 and 3.5 billion years ago.
There are several geological indications that Mars in its past had much more humid and hotter weather than today's dry and cold conditions.