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Is there liquid water on Mars?

By Clare S Ryan, on 13 September 2011

Since astronomers first glimpsed the surface of Mars through telescopes in the late 1900s, scientists have been fascinated by the idea that water – and along with it, the possibility of life – exists there. Dr Peter Grindrod (UCL Earth Sciences) gave this year’s Halstead Lecture at the British Science Festival to take the scientifically inclined on a whistle stop tour, complete with stunning images, of how our understanding of water on this mysterious planet has developed in the past 150 years.

Dr Grindrod is a geologist with a difference. Instead of looking at the rocks and landscape of our own planet, his work is focused much further afield, specifically the geology of Mars. To do this, he looks at images of the surface of the planet, searching for clues as to whether or not water, or specifically liquid water, is present on Mars.

Since the dawn of the space race in the 1960s, numerous missions have tried (and some failed) to go to Mars. Grainy images sent back to Earth in those early days gave scientists tantalising hints of what appeared to be river patterns on the surface.

The lecture explained how, with the help of increasingly advanced technology, each mission since then has led to a step change in the understanding of water on the planet.

The delta deposits and channels in the Eberswalde crater provide a clear indication of liquid surface water during the early history of Mars.  Credits: ESA/DLR/FU Berlin (G. Neukum)

So is there water on Mars now? The answer is a definitive ‘yes’, but perhaps not as you might expect it. Due to the temperature and pressure on the planet, water is most likely to be found as either ice contained in polar ice caps or water vapour in the planet’s thin atmosphere, rather than liquid water on the surface. However, satellite images, which have now mapped the whole planet, and experiments carried out by robot ‘landers’ have established that water is also stored beneath the surface of the planet as hydrated minerals – much like the water stored under the ground in Epsom in Surrey where the eponymous salts originate.

But what about those river patterns? Scientists think that it’s likely that Mars was once a very different planet, with a thicker atmosphere and a warmer wetter surface that featured rivers and even oceans. Over the past 3 billion years, it has become a much dryer, dustier and colder planet.

Dr Grindrod’s talk was peppered with images ranging right back to the 1900s and ending with ones taken just days ago by the NASA’s Phoenix mission. There are also are exciting times ahead in this field with the upcoming launch of the ExoMars programme, a joint initiative between ESA and NASA.

This excellent lecture generated loads of discussion and highlighted just how much more there is to know about Mars, notwithstanding the big question of whether we can find signs of life there. In the questions section in the last ten minutes, I learnt that it snows on Mars (!), there are probably caves with stalagmite formations and scientists are now interested in the possible effects of acid rain on the planet. A perfect end to a lively talk!

Clare Ryan is a manager in the UCL Media Relations team.

Image caption: The delta deposits and channels in the Eberswalde crater provide a clear indication of liquid surface water during the early history of Mars. Credits: ESA/DLR/FU Berlin (G. Neukum)

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