Reports of Mars' geological death might have been greatly exaggerated, according to researchers working on the European Space Agency's Mars Express mission.

Images from the orbiter reveal volcanic cones at the planet's north pole that are unmarked by craters, suggesting that they erupted relatively recently, the BBC reports.

The amount of cratering on a planetary surface is a widely accepted method of estimating that surface's age, and assumes a steady rate of impacts on planets, over the last four billion years or so.

Dr. Gerhard Neukum from the Free University in Berlin, and the principal investigator for the High Resolution Stereo Camera (HRSC) on Mars Express, told delegates at a meeting of planetary scientists in Cambridge:

"Mars is a planet that was very recently active - maybe one, or two, or three million years ago."

He said that the cones give him the impression that Mars could still be geologically active, even today. Volcanic activity on Mars is thought to have reached a maximum around 1.5bn years ago.

He acknowledged that it was possible that if the cones were ancient features, any cratering could have been eroded by the Martian winds. But he said the region - which features somewhere between 50 and 100 volcanoes - showed no other wind-related features. He also noted that some traces of the craters should remain, and that he could see none.

Dr. Neukum also proposes that volcanic activity and glacial activity on the planet are linked, but other scientists think the inclination of the planet's orbit around the sun has a bigger influence on the movement of water. ®

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