Artist's concept of Phoenix lander.From The Washington Post:
Soil Tests Also Hint at Past Presence of Liquid Groundwater
Icy snow falls from high in Mars's atmosphere and may even reach the planet's surface, scientists working with NASA's Phoenix lander reported yesterday.
Laser instruments aboard the lander detected the snow in clouds about 2 1/2 miles above the surface and followed the precipitation as it fell more than a mile. But because of limitations with the technology, it was unclear whether any of the powdery stuff made it all the way to the surface.
"Nothing like this view has ever been seen on Mars," said Jim Whiteway of York University in Toronto, lead scientist for the Canadian-supplied Meteorological Station on Phoenix. "We'll be looking for signs that the snow may even reach the ground."
In addition to finding snow, the Phoenix team reported discovering material in the Martian soil that had once been dissolved in water -- clays and calcium carbonate (limestone) that could have formed only in the presence of liquid water. Although the lander's instruments earlier found water ice below Mars's polar surface and had photographed surface fog and clouds, it has found nothing like liquid water on the surface.
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