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From The TimesMarch 21, 2008

Mars salt basins signal water from possible life in the pastMark Henderson, Science Editor
Salt deposits have been discovered in numerous places on Mars, in new research that identifies where water was once in abundance and which could point to the past existence of life.

Observations with the Themis thermal camera on Nasa’s Mars Odyssey orbiter have revealed the presence of chloride salts at more than 200 locations in the Red Planet’s southern hemisphere.

All are found in ancient, cratered regions, and occur in basins that appear to be fed by channels. They are likely to have been laid down by the evaporation of pools of standing water that were present when Mars was warm and wet, several billion years ago.

The findings, published today in the journal Science, offer further evidence for the past existence of liquid water on Mars, which has been confirmed by different strands of research.

They also highlight regions that may have been particularly wet in the past, which would be good candidate sites for the existence of primitive life in Martian history. These may be promising places to send future Mars lander missions, as organic materials are likely to have been concentrated in these salt basins.

Professor Philip Christensen, of Arizona State University, the principle investigator for the Themis camera, said: “Many of the deposits lie in basins with channels leading into them. This is the kind of feature, like salt-pan deposits on Earth, that’s consistent with water flowing in over a long time.”

The researchers think the salt deposits were laid down in Mars’s Noachian epoch, between about 3.9 billion and 3.5 billion years ago.