Life on Mars...er, we may have been wrong, says NASA

THERE was great excitement when NASA announced it had found flowing water on Mars – as it meant a sign of possible life.

But, two years later, hopes of spotting little green Martians have rather dried up. Scientists have now said that streaks on the planet’s surface are more likely to have been caused by sand, not water.

Research published in the journal Nature Geoscience suggest these lines appear more like dry, steep flows of sand, rather than water trickling downhill. If water is present, they said, it’s likely a small amount – and probably not capable of hosting life. NASA, though, said the jury is still out.

The lead scientist for NASA’s Mars exploration program, Michael Meyer, points out that the latest study does not rule out the presence of water. But he acknowledges: ‘It just may not be as exciting as the idea of rivers going down the sides of cliffs.’

NASA’s spacecraft, the Mars Reconnaissance Orbiter, provided the images of these so-called recurring slope lineae, or RSL. Thousands have been spotted on Mars.

The team, led by the US Geological Survey’s Colin Dundas in Flagstaff, Arizona, measured 151 of these lines at ten sites.

Most of them end with a slope measuring between 28 degrees and 35 degrees, a match for active sand dunes on both Mars and Earth, according to the researchers.

A thin layer of dust on top that shifts and sometimes brightens the surface might help explain why these streaks seem to occur in the Martian summertime and then disappear, only to reappear the next year. If these are dry lines ‘this suggests that recent Mars has not had considerable volumes of liquid water,’ the researchers write.

NASA announced the water had been found on Mars in September 2015.

Dr Dundas and his colleagues stress that many questions remain, demanding further study. Dr Meyer added: ‘I still think that Mars poses a great potential for having had life early on in its history.

‘As long as that’s true, we also have a reasonable possibility of life still being on Mars. It just happens to be cryptic or well hidden.’