NASA ’s Viking probes were colossally disappointing for those look for life on Mars – not only were there no augury of life , we did n’t even find its essential edifice blocks . Or perhaps we just did n’t know what to look for .
NASA ’s current Martian Internet Explorer , the Phoenix Mars Lander , made a surprise discovery in 2008 that force scientists to reassess the previous Viking data . Phoenix found percholate , an oxygen / Cl ion , in the land around its landing pile . One of percholate ’s most important properties is that oxidizes material around it when heated , make compounds like chloromethane and dichloromethane . Those two materials were the only organic molecule Viking found when it carried out its tests back in 1976 . And how did it do those test ? By heating the soil . If percholate was in the soil , it would have bring out exactly those two molecule .
NASA scientist Chris McKay explains how Phoenix ’s determination exchange our rendition of the original Viking results :
“ The lack of organics was a big surprise from the Viking . But for 30 years we were looking at a jigsaw puzzle with a piece missing . Phoenix has ply the missing piece : perchlorate . The perchlorate discovery by Phoenix was one of the most important issue from Mars since Viking . It could baby-sit there in the Martian soil with organic fertilizer around it for billions of years and not kick downstairs them down , but when you ignite the dirt to check for organics , the perchlorate destroys them speedily . ”
The chlorine compounds we originally found were discount as contaminants from Viking ’s cleanup fluids , in part because the ratio of Cl isotope present in the sample matched the ratio of those isotopes on Earth . In the absence seizure of any other grounds of organic molecules , NASA scientists envision that was just more proof the sample distribution was contaminated . Still , there ’s no rationality why the same isotope ratio could n’t exist on both Earth and Mars , and that ’s a question future probes can look into .
McKay and his co-worker stress that this does n’t intend Viking actually find life – or even that the organic molecules were native to Mars , as they could have been deposit by meteorite impingement . Still , however they fetch there , if there were constituent molecules at the Viking site , then that means such compounds can survive on the Martian aerofoil for jillion , maybe even billions of eld .
If that ’s the typeface , then the surface territory of Mars – which is unsurprisingly the easy part of the planet for investigation to examine – could be a great place to research for more complex sign of life , such as DNA . NASA will get a chance to test out a heap of these idea when the new Curiosity scouter make the red planet in 2012 .
[ NASA JPL ]
AstrobiologyPhoenixScienceSpace
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