Most of Mars’ ancient oceans could still be hidden below its dry and dusty surface, according to European space scientists. Observations by an orbiting spaceprobe show that vast seas may have disappeared underground along with most of its atmosphere.
The findings, following two years of study by Europe’s Mars Express mission, come just weeks after Nasa reported signs of liquid water flowing on the surface.
Scientists believe that billions of years ago, the Red Planet was a warm and wet, blue world like Earth. Surface features such as channels and gullies show that there were seas half a mile deep. But some sort of catastrophic climate change turned Mars into a dry and icy desert.
It was thought that most of the Martian carbon dioxide atmosphere and water were blown away into space by winds from the Sun. However, observations from Mars Express – the mothership that carried Britain’s ill-fated Beagle 2 lander – show that the planet is losing only 20 grams (0.7 oz) of air a second into space.
Calculating backwards, this suggests that only a small fraction of Mars’ air and a few centimetres of water have been lost that way. Space scientist Stas Barabash, of Sweden, tells the journal Science that Mars’s ancient seas may be stored in a vast underground reservoir.
The Mars Express image shown here is of what resembles pack ice – part of a dust-covered frozen sea near the Martian equator, according to UK Mars scientist John Murray, of the Open University. He believes that microbes could be lying dormant beneath the ice. Photo: ESA.