BOSTON -- Scientists studying the latest photographs from Mars may have spotted the first evidence of ice outside the planet's polar ice caps.
Pictures released for the first time Wednesday at the American Geophysical Union's spring meeting show a crater some 30 miles across with a darker area 12 to 18 miles wide at the bottom.
The discoloration indicates a deposit of some sort -- maybe frozen mud or sand -- which could indicate ice is present or water once was, said Mike Malin, a consultant who helped design cameras for the Mars Global Surveyor.
"If you're going to find life anywhere, that's where you're going to find it. Water is essential for life," Malin said.
Malin and other scientists associated with the Surveyor mission also said there may be other explanations for what they've spotted in the crater, such as volcanic activity.
But the presence of cracks at the crater's rim -- located about 2,400 miles south of Mars' equator -- are consistent with something seeping into the giant pit from its edge, Malin said.
The cracks look like the vertical lines on chapped lips.
The photos are the latest in a series from the Mars Global Surveyor, a spacecraft orbiting the planet since last fall. Its orbit is closer to Mars' than any previously attempted, about 108 miles from the surface.
The latest pictures have 10 to 12 times better resolution than any previously taken of the crater.
In addition to the photographs, Surveyor is collecting topographical information about Mars detailing its striking canyons and spiraling troughs that slice through the planet's northern polar ice cap.
The Martian polar landscape includes soaring 12,000-foot peaks and plunging 3,600-foot channels.
Profiles of the ice cap will be used to help scientists understand the effects of solar radiation, ice flow, wind and dust on Mars.