Science Story

04 July 2009 13:59 BST

Ancient Mars was 'water rich'

Unlike the dusty red planet Mars is today, it was once rich in water for a long period of time, according to scientists.

They argue that the discovery provides more evidence Mars could have been a more habitable environment that it is at present.

Scientists at 14 institutions found that vast regions of the southern highlands of the Red Planet hosted a water-rich environment by studying data from instruments aboard the Mars Reconnaissance Orbiter (MRO).

They further argue that the water played a sizeable role in changing the minerals of a variety of terrains in the Noachian period – about 4.6 billion to 3.8 billion years ago.

The researchers used the MRO data to look for phyllosilicates - clay-like minerals that preserve a record of water's interaction with rocks - in deposits in localised spots such as craters, valleys and dunes all over the planet.

Among the highlights were phyllosilicates in fans and deltas within three regions, most notably the Jezero crater.

Writing in the journal Nature, the scientists argue that the Jezero discovery marks the first time hydrated silicates have been found in sediments clearly lain by water.

The team also found phyllosilicate deposits in thousands of places in and around craters, including the pointed peaks located at the centre of some of the depressions.

The latter example suggests that water was present four to five kilometres below the ancient Martian surface due to the generally accepted principle that crater-causing collisions excavate underground minerals that are then exposed on the crater peaks.

"Water must have been creating minerals at depth to get the signatures we see," said John Mustard, professor of planetary geology at Brown University.

"What does this mean for habitability? It's very strong. It wasn't this hot, boiling cauldron. It was a benign, water-rich environment for a long period of time."