Phoenix lander finds snow on Mars

“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 that they had discovered material in the Martian soil that had once been dissolved in water — clays and calcium carbonate (limestone) that could only have formed in the presence of liquid water. While the lander’s instruments had 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.

The presence of nutrients and other material that once dissolved in water, however, plus the continuing presence of water as snow, vapour and ice, is leading researchers to the conclusion that Mars’s polar regions might have supported life in the past when the region was much warmer. Because Mars wobbles on its axis far more than Earth — in some very long-term cycles the poles actually face the sun — the northern region where Phoenix landed has, in the past, been warm.

“Is this a habitable zone on Mars? I think we are approaching this hypothesis,” said Peter Smith of the University of Arizona, the lander’s principal investigator.

In addition, Michael Hecht of NASA’s Jet Propulsion Laboratory said that further analysis of the Martian dust by the lander’s on-board laboratory has determined that it is as alkaline as ocean water, with a pH of 8.3. He said this finding also suggests that life could have existed on Mars.

The snow, along with frost and fog, began to appear about a month ago, Whiteway said, as temperatures cooled on Mars. “This is now occurring every night,” he said.