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newscientist 00602.txt

#Rover finds first life-friendly environment on Mars Microbes could have lived on Mars . Though we don't know yet if they actually did NASA's Curiosity rover has found the first definitive evidence that the Red planet was suited once to life and perhaps the first direct evidence of life-friendly conditions anywhere beyond Earth. This is probably the only definitively habitable environment that we've described and recorded said David Blake principal investigator for the rover's Chemistry and Mineralogy instrument Chemin. Determining if Mars could have supported ever life was the rover's chief goal when it landed in Gale crater in August 2012. Curiosity was expected to hit pay dirt months from now when it reached a 5-kilometre-high mound of layered sediments in the middle of the crater. Instead the discovery came from the rover's first sample of the insides of a Martian rock drilled on 9 february near an ancient stream bed in an area called Yellowknife Bay. A scoop of the powdered dust was delivered to Curiosity's onboard chemistry lab to analyse its composition. The team was looking for three things that together spell habitability: a non-acidic environment; enough water for microbes to thrive in; and minerals that could act like batteries allowing electrons to flow and bring energy to any potential organisms. They found all three. The instruments showed that between 20 and 30 per cent of the dust is called a clay mineral smectite which forms in the presence of water. More importantly they found calcium sulphate salts which form in non-acidic water. They also found sulphur dioxide and hydrogen sulphide two forms of sulphur that have lost respectively and gained electrons and so could have acted as microbial energy sources. All these clues point to ancient Mars hosting neutral slightly salty liquid water that could have supported primitive life. This rock frankly looks like a typical thing we would see On earth says Curiosity project scientist John Grotzinger. We have found a habitable environment that is so benign and supportive of life that probably if this water had been around and you had been on the planet you would have been able to drink it. The rover's Sample Analysis at Mars instrument (SAM) also found carbon dioxide and hints of other carbon-based molecules in the drilled sample. Part of Curiosity's mission is to find preserved organics compounds that include both carbon and hydrogen. That would be a direct sign that something actually lived on the Red planet. These new hints of carbon are tantalising but the team isn't getting carried away. This was the very first sample that had gone through the drill. It's always possible that residual carbon that was on the drill bit was in the sample said Paul Mahaffy SAM's principal investigator. We're very interested in seeing if they persist. Grotzinger pointed out that certain microbes can live on CO2 even in the absence of organics. The fact that Paul is able to show that CO2 spike that's what we're real excited about he says stressing that although CO2 is inorganic it can still be used by a microbe. Curiosity will keep heading for the layered sediments in the crater's central mound officially named Aeolis Mons but dubbed Mount Sharp by the rover team. Mission scientists want to compare the layers with the rocks in Yellowknife Bay to figure out how they are related and Mount Sharp may still be the best hope of finding preserved organics . But now that they've found a habitable environment the team will keep the rover in place a while longer says Grotzinger. Depending on what we find because we're discovery-driven if it continues to look promising we'll do more work he said. If not we'll get on the road. In the immediate future Curiosity will be going temporarily silent. Mars is going to pass behind the sun from Earth's perspective for the entire month of April blocking communications between the rover and mission control. The next drill scoop will have to wait until the planet comes back into Range in the meantime the science team has plenty of data to fuel new discoveries and daydreams. I have an image now of possibly a freshwater lake on a Mars with a thicker atmosphere maybe a snowcapped Mount Sharp said NASA science administrator John Grunsfeld. It makes me want to go

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