From: Frank Warren <frank-warren.nul> Date: Wed, 03 Mar 2004 06:33:54 -0800 Fwd Date: Wed, 03 Mar 2004 14:50:38 -0500 Subject: Mystery Over Red Planet Was A Wet Planet Source: The Age http://www.theage.com.au/articles/2004/03/03/1078295445809.html March 4, 2004 Mystery over - Red Planet was a wet planet By Stephen Cauchi Science Reporter Decades of speculation on whether Mars once had life-sustaining water ended yesterday as NASA announced that the landing site of its rover, Opportunity, used to be "soaking wet". Mission scientists told a press conference at NASA headquarters in Washington that two weeks of intensive rock study by Opportunity unambiguously pointed to a "persistently wet environment that could possibly have been hospitable to life". The historic announcement had been hotly anticipated for the past week as scientists pored over Opportunity's analysis of Martian rocks, especially a layered specimen called El Capitan. "Were these rocks acted upon, were they altered by liquid water? The answer to that question is, definitely, yes," said Steve Squyres, the principal investigator for Opportunity's science payload. "Liquid water once flowed through these rocks. It changed their texture and it changed their chemistry... this was a ground water environment that would have been suitable for life. That doesn't mean that life was there. We don't know that." Several lines of evidence pointed to the conclusion, scientists said. These included the rocks' distinctive layering and pockmarked indentations. "This distinctive texture is familiar to geologists as the sites where crystals of salt minerals form within rocks that sit in briny water," NASA said. Sulphate salts were also found. According to NASA, "rocks with as much salt as this Mars rock either have formed in water or, after formation, have been highly altered by long exposures to water". The rover also found jarosite, an iron-sulphate mineral pointing to "an acidic lake or acidic hot springs environment". Opportunity landed on Mars on January 25 in the Meridiani Planum region, selected because it is rich in a mineral - grey hematite - that usually forms in water. Its twin, Spirit, is on the opposite side of the planet in Gusev crater, which may have been a lake. Scientist have long suspected that the Red Planet was at least partly blue because of distinctive erosion patterns that seem to have been carved by flowing water. NASA did not speculate when the water existed, why it vanished or where it went. Mars may still have water, albeit underground in reservoirs, but its surface is totally dry. It also has frozen water mixed with frozen carbon dioxide, or dry ice, in its polar caps. Monash University geosciences lecturer Marion Anderson, a member of the committee that selected Opportunity's landing site, said the news was "better than what we could have hoped for". By checking the rock layering, Opportunity will investigate if a lake once existed at the site or if hot water seeped to the surface from underground, she said. "These are pretty much the only two (scenarios) that would give the structures that we're seeing on these rocks," she said. "In the next 10 days, Opportunity will see which of these two is what happened." Ms Anderson said Meridiani Planum would be a "prime target" for future Mars landers looking for evidence of past Martian life. "It gives us more of a reason to look for life than ever before. If Beagle 2 had survived it might have given us that answer, but it didn't." NASA scientists agree. "It is clear that we are going to have to do a sample return (mission)," NASA administrator Ed Weiler said. A critic of the theory that Mars once had water, Nick Hoffman of Melbourne University, conceded the findings "absolutely guaranteed there was water on Mars". "I'll eat one slice of humble pie on this one," he said. Dr Hoffman said he believed the rocks were wet because of water seeping from the ground, not because they were in a lake. He said the water may have existed as long ago as 3.5 billion years, and probably in many places. "There was water seeping out of the ground just about everywhere. There was a lot of water. It's very exciting."
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