Signs of recent glaciers, volcanoes on Mars

By Robert Roy Britt

updated 4:11 p.m. ET March 16, 2005

New images of Mars reveal that flowing water, large glaciers and active volcanoes have scoured the planet in recent geologic times.

Scientists say Mars has been geologically active in the past few million years — an eyeblink in the planet's 4.5-billion-year history.

Three studies appearing in the March 17 issue of the journal Nature add to a growing body of evidence that points to recent liquid water and present vast stores of underground ice near the planet’s equator.

Combined, the research provides further impetus to search Mars for signs of life, scientists said.

Hot spots
Billions of years ago, Mars was warmer and wetter than today, according to evidence of past water seen by NASA's two Mars rovers currently exploring the planet. Scientists are eager to learn whether water has graced the planet in recent times, because liquid water is a key ingredient for life as we know it.

Likewise, if the red planet remains volcanically active, local hot spots could serve as incubators for microbial life, as they do in otherwise desolate places on Earth.

No firm evidence for life on Mars has been presented, but in recent months signs of methane in the Martian atmosphere have piqued the curiosity of astrobiologists. The methane could be generated by volcanic activity or mark the signature of subsurface life, but its detection remains controversial nonetheless.

In the three new papers, researchers lay out the strongest case yet that volcanism may be ongoing and glacial activity recent. The observations were made by the High Resolution Stereo Camera (HRSC) on the European Space Agency’s Mars Express Mission.

Explosive eruptions about 350 million years ago created depressions on the flanks of the volcano Hecates Tholus, according to a study led by Ernst Hauber of the German Aerospace Center. And just five million years ago, glacial deposits formed inside these depressions, the scientist concludes.

The finding adds to a December study showing five volcanoes on Mars had been active as recently as two million years ago.

Equatorial glaciers
A group led by geologist James Head of Brown University reanalyzed landforms first thought to be glacial during the Viking missions of the 1970s. Head and his colleagues found the features are indeed evidence of geologically recent glacial activity near the equator.

"Mars is very dynamic," according to Head. "We see that the climate change and geological forces that drive evolution on Earth are happening there."

Glaciers appear to have moved from the Martian poles to the tropics between 350,000 years ago and 4 million years ago.

"This glaciation may be a response to recent changes in the incidence of sunlight induced by variations in obliquity of the planet’s spin axis," said Victor Baker, who was not involved in the research.

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