February 23, 2005—The miles-wide, ice floe-shaped landforms in this new aerial view of Mars may be just that—ancient ice sheets. Noting their similarity to floes at Earth's poles, a team of European scientists speculates that an entire frozen sea is buried intact in this equatorial region. Released today by the European Space Agency, the image was captured by the agency's Mars Express spacecraft.

The scientists believe that a catastrophic event five million years ago sent subterranean water gushing onto the Martian surface, creating a sea. The red planet's frigid temperatures quickly turned the sea's surface to ice, which later broke up into the sheets seen buried above. Eventually the sea itself froze, and the entire region was later blanketed by dust, the researchers say.

Since Mars was no warmer five million years ago than it is today, the finding bolsters the possibility that water still flows underground here. And where there is water, there is the possibility of life.

—Ted Chamberlain

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