MELISSA BLOCK, HOST:
The latest results are in for the NASA's Mars science laboratory, the six-wheeled Curiosity rover that landed on Mars last August. The results show hints of something exciting but just hints. As NPR's Joe Palca reports, rover scientists are making sure not to raise expectations.
JOE PALCA, BYLINE: Many of the rover scientists were in San Francisco today for the annual meeting of the American Geophysical Union. It was always the plan to present early results from the mission, but expectations for big news were raised when one of the instruments on board the rover appeared to detect organic molecules.
Paul Mahaffy is the lead scientist on the instrument known as SAM. Having already found signs of water on Mars, finding signs of organic material would be another piece of evidence that there might, might, might have once been life on Mars. But Mahaffy said at a press conference today, no news yet.
DR. PAUL MAHAFFY: SAM has no definitive detection to report of organic compounds with these first set of experiments.
PALCA: Mahaffy says SAM definitely saw simple organic compounds, compounds made of carbon, when it analyzed its first soil sample last month. It also saw compounds made with chlorine.
MAHAFFY: The reason we're saying we have no definitive detection yet of Martian organics is that we have to be very careful to make sure both the carbon and the chlorine are coming from Mars.
PALCA: Mahaffy says they cleaned the instrument before it left Earth and cleaned it some more once it got to Mars. But he says it's still possible the carbon the instrument is seeing may be a contaminant from Earth. And Mahaffy emphasized that the carbon compounds, if they really are in the soil sample, may have come from nonbiological chemical reactions.
MAHAFFY: The carbon, for example, could also come from inorganic carbon.
PALCA: But seeing those carbon molecules would be a hint that carbon that did come from something biological might have survived on Mars and could be found. Rover chief scientist John Grotzinger of the California Institute of Technology said it will take a while to make sense of all the data coming from the rover's suite of instruments.
DR. JOHN GROTZINGER: There's not going to be one single moment where we all stand up and, on the basis of a single measurement, have a hallelujah moment.
PALCA: Grotzinger says that's just the way it works in science. Joe Palca, NPR News.
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