Mars water debate ebbs and flows

Has there been, or is there even now, water on Mars is a question that provokes vigorous debate amongst scientists. Just in the last month, data from Nasa's Mars Reconnaissance Orbiter was re-examined and previously promising evidence for free flowing water some time in the planets past was downgraded from a probable to a maybe. Alfred McEwen from the MRO project suggested that incredible images which appeared to show sudden explosive outpourings of water in just the last year might not even have been water. "The thing we've found with six examples is that they all occur on some of the steepest slopes, steep enough that dry movement, dry flow, could have been sufficient to explain these deposits," said Professor McEwen.

But don't give up on that watery Mars yet. Just in the last few days University of Guelph researchers say they may have identified visible signs of water, in a white, salty substance churned up by the wheels of the Spirit rover. If the material is indeed what they think it is, then the deposits spotted in the Columbia Hills region of the planet could contain up to 16 per cent water. Normally the chemical analyser on Spirit, called an alpha particle X-ray spectrometer would not be able to extract this sort of information, but some clever work on the data has revealed the evidence for water, which had previously been dismissed as interference. So it's not the most conclusive piece of evidence, but the debate is clearly not yet closed.