Carbon dioxide, a greenhouse gas that has become a bane of modern society, may have saved Earth from freezing over early in the planet's history, according to the first detailed laboratory analysis of the world's oldest sedimentary rocks.

Probes designed to find life on Mars do not drill deep enough to find the living cells that scientists believe may exist well below the surface of Mars, according to research led by UCL (University College London). Although current drills may find essential tell-tale signs that life once existed on Mars, cellular life could not survive the radiation levels for long enough any closer to the surface of Mars than a few metres deep - beyond the reach of even state-of-the-art drills.

Earlier this month ESA's Rosetta had a first look at asteroid 21-Lutetia, one of the targets of its long mission. The onboard camera OSIRIS imaged the asteroid passing through its field of view during the spacecraft's gradual approach to Mars. The planet will be reached on 25 February 2007 for the mission's next gravity assist.

Two U.S. robotic rovers are entering their fourth year exploring opposite sides of Mars, an unexpected length of time for a mission planned for only three months. Yet, now after three years, the mechanical geologists keep plodding along, studying Martian rocks and soil. Although they show certain signs of aging, VOA's David McAlary reports that new computer software has given them expanded capabilities, proving you can teach an old robot new tricks.

Scientists are finding an older, craggier face of Mars buried beneath the surface, thanks to a pioneering sounding radar co-sponsored by NASA aboard the European Space Agency's Mars Express spacecraft. In a paper researchers say radar echoes captured by the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) instrument strongly suggest there are ancient impact basins buried beneath the lowland smooth plains of the Martian northern hemisphere.

Layers on Mars are yielding history lessons revealed by instruments flying overhead and rolling across the surface.

With results that the principal investigator of the Mars Express MARSIS radar, Giovanni Picardi, from the University of Rome 'La Sapienza', describes as unprecedented, Mars is showing scientists that it has an older, craggier face buried beneath its surface.

NASA's announcement yesterday of evidence that water still flows on Mars, at least in brief spurts, demonstrates that the view of Mars as a very dry planet should be reevaluated, says Dawn Sumner, professor of geology at UC Davis. Recent work from by Sumner and graduate student Greg Chavdarian also supports the presence of liquid water near the surface.

NASA photographs have revealed bright new deposits seen in two gullies on Mars that suggest water carried sediment through them sometime during the past seven years.