Mars, the red planet, may not after all be the dead planet. New research yesterday by European scientists suggests that volcanoes on Mars last erupted only 2 million years ago and could erupt again.
And dramatic photographs by a high-resolution stereoscopic camera aboard the European spacecraft Mars Express, in the journal Nature, suggest that glacial ice could survive on the western scarp of Olympus Mons, the biggest volcano in the solar system.
Last week, Nature's US rival Science named the confirmation of water on Mars as the scientific breakthrough of the year. But the revelation that Mars could be geologically "alive" is even more dramatic.
Volcanos eject water and atmospheric gases, recycle mineral nutrients and reshape landscapes.
POSSIBILITY OF LIFE?
The discovery once again raises the possibility that life might survive on Earth's colder, smaller, dustier neighbour.
"A year or two ago any planetary scientist I know would have said no, Mars has been quiet; it is no longer geologically active," said Alan Moorhouse, of the European spacecraft operations center in Darmstadt, Germany.
"To find that there has been volcanic activity as recently as 2 million years ago is astounding. In geological terms, 2 million years is yesterday. Anything that happened yesterday can happen again today."
Mars Express began orbiting the red planet in January, after delivering the ill-fated British lander Beagle 2, and began a series of close approaches to map the topography in finer detail than ever before.
For the first time, earthbound geologists could study geological features, drainage patterns, evidence of volcanic eruption and traces of ancient ice scars.
From an altitude of only 226km, the spacecraft's stereo camera pinpointed gigantic ridges, landslides, glacial deposits and lava fields at 7,000m on the scarp of Olympus Mons.
"You see not only color but also three-dimensional pictures. It's absolutely fantastic," Moorhouse said.
The detailed imagery meant the researchers could begin to judge the age of volcanic flows from the number of meteor impact craters that pitted them. Scientists have been sure for years that Mars once had a dense atmosphere, and certainly active volcanoes. But until the arrival of Mars Express, they had assumed Mars had been inactive for hundreds of millions of years.
Evidence today, outlined by researchers from Berlin, Moscow, Hawaii, Providence in Rhode Island and Milton Keynes, UK, is that Mars may have been geologically active for at least 80 percent of its history, and the most recent eruptions may be only 2 million years old.
"That is the date one gets from crater counting," John Murray said, of the Open University, one of the authors. "So if we now have some very young craters, it certainly does suggest that Mars has been volcanically active all the way through and possibly will be active in the future."
Earlier this year, instruments aboard Mars Express confirmed the presence of methane in the Martian atmosphere. On Earth, methane is linked with biological decay or digestion.
It could have a volcanic origin. But if the methane comes from volcanic fissures, then even though the equatorial surface of Mars is colder than the Antarctic, there must be heat below the surface.
Where there is heat, there could be liquid water, and a potential home for microbial life.