EUROPEAN SPACE MISSION: Using sophisticated radar aboard the European Mars Express spacecraft, scientists have for the first time peered into the heart of Mars, uncovering ancient geological structures and reservoirs of ice more than a mile beneath the arid surface.
"We're looking at the third dimension on Mars, something no other mission has done before," Agustin Chicarro, project scientist for the European Space Agency, said during a Paris news conference on Wednesday.
Mr Chicarro said instruments aboard the spacecraft, which has been orbiting Mars since December 2003, have revealed what looks like an ancient impact basin in the temperate region and fresh stores of ice near the North Pole.
The craft's on-board radar, known as the Mars Advanced Radar for Subsurface and Ionospheric Sounding, did not, however, uncover any evidence of liquid water underground.
"We certainly can say we observed a significant amount of subsurface water in the form of ice," said team member Jeffrey Plaut of the National Aeronautics and Space Administration's Jet Propulsion Laboratory, "but there's no current evidence yet for subsurface liquid water."
The question of liquid water on Mars is key to determining whether some form of rudimentary life could have, or still might, exist on the planet.
Although the Martian surface is too inhospitable to support life as we know it, scientists have speculated that rudimentary life forms could exist in relatively warm, subsurface pools.
In the north pole scan, scientists were able to penetrate through about a mile of ice to subsurface soils, the boundary region where a pool might form.
However polar temperatures plunge to minus 200 degrees Fahrenheit, too cold for any melting, even at great depths, and much too cold for any kind of life similar to that on Earth.
Mr Plaut emphasised that Mars Express was just beginning to scout the interior of Mars.
In the next year, controllers on Earth will be specifically looking for the radar signature of liquid water in the temperate areas, where the air temperature can occasionally rise to 32 degrees
Other instruments aboard the ESA's spacecraft filled in the portrait of the ancient Mars, depicting a planet that now appears much less friendly to any form of life than previously thought.