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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. The new studies suggest that Mars is currently in an interglacial period. As the planet tilts closer to the sun, ice near the equator is expected to vaporize.
In a third paper, additional detail is provided on a previous announcement of a frozen chunk of water - roughly the size of the North Sea - that formed in the last five million years near the Martian equator. The area is thought to have been flooded by liquid water carried along by volcanic eruptions in a region called Cerberus Fossae.
"The three papers provide an overwhelming case for new thinking about recent geological activity on Mars," writes Baker in an analysis of the work. Cataclysmic flooding
Baker said the findings support a 1991 hypothesis, then considered outrageous, that Mars has experienced episodes of cataclysmic flooding in modern times. Water is thought to have formed temporary seas, but researchers had long assumed it all evaporated into the thin Martian air.
Many scientists now agree that much of the water remained. "The evidence from HRSC for recent aqueous activity suggests that the water is still present, as ice on the ground and water deep beneath the surface," Baker said. In early May, Mars Express will deploy a radar instrument that should be able to detect subsurface water and ice several miles down. "Evidence from the latest pictures indicates that the water will surely be there," Baker said.
Where there is water, there could be life. Many investigations on Earth have turned up extremophiles -- microbes living in frigid conditions, thriving in extremely salty water, and gathering around volcanic vents. Last month scientists announced the discovery of bacteria that had survived in a state of frozen suspension for 32,000 years.
Studies of Mars point to evidence of the presence of liquid water on the planet's surface and a vast amount of underground ice near the equator within the past few million years. Liquid water is believed to be a key ingredient for life, therefore the presence of water on Mars helps support chances of extraterrestrial life, reported the journal Nature today. In the studies, strong indications of glacial and volcanic activity were presented. The combined research on this subject, including a study in December 2004 indicating that five volcanoes were active as recently as two million years ago, justifies further search for signs of life on Mars scientists say.

A few million years is a mere minute on the geological timescale of Mars which has been around for 4.5 billion years.

The scarred surface of Mars cannot be attributed solely to asteroids. New images of the landscape taken by the High Resolution Stereo Camera (HRSC) on the European Space Agency's Mars Express Mission show that flowing water, large glaciers and active volcanoes have also taken their toll on the face of Mars.

Some evidence collected by two Mars rovers that NASA sent to explore the planet shows that Mars was hotter and more humid millions of years ago than it is today. Also important were active volcanoes that can stimulate the forming of microbial life as they do here on Earth. Scientists recently discovered bacteria near the mouths of undersea volcanic vents on Earth where bacteria live off sulfur instead of oxygen and discharge methane as a by-product of their life cycle. Though controversial, the discovery of signs of methane gas in Mars' atmosphere also interests researchers who believe it indicates the possibility of subsurface life.

Geologist James Head of Brown University led a group of researchers who examined landforms thought to be glacial during the Viking program in the 1970s. They found evidence that glaciers moved from the poles to the equator between 3.5 and 4 million years ago, suggesting that Mars is currently in an interglacial period. 

A third study looked at an area of frozen water roughly the size of the North Sea that formed near the equator around five million years ago. It is now thought that the ice was once liquid water carried along by volcanic eruptions in a region known as Cerberus Fossae.

Researchers have long assumed water on Mars had all evaporated into the Martian atmosphere. A 1991 hypothesis, then considered outrageous by suggesting Mars was no stranger to floods, is now supported by recent findings. The HRSC data suggests water is still present both in liquid form and ice. Mars Express will deploy a special radar instrument in early May which should be able to detect water and ice even several miles beneath the surface.

Should water be found on Mars, the chances of finding life are great. Many extremophiles, bacteria living under extreme conditions such as extreme salinity or heat, have already been discovered on Earth. In February 2005, scientists announced the discovery of bacteria that survived in a state of frozen suspension for 32,000 years. 

Likewise on Mars, a sample of ice could offer great insight into the evolution of the Martian environment and atmosphere. These discoveries may offer a great chance to get objective evidence for Mars research.