BBC: Mars not a watery world
Mars 'not a watery world'
Hopes that Mars once had vast oceans of water and perhaps microbial life have suffered a setback.
A US space agency (Nasa) space craft has failed to find evidence that the Red Planet was once a warm, watery world like the Earth.
Scientists have been searching for decades for signs of water-related carbonate minerals on the Martian surface.
Mars Global Surveyor, which is orbiting the planet, has at last come up with the goods.
But it has found only traces of carbonates in dust, which probably came from the atmosphere rather than rocky outcrops deposited by oceans.