Oskaloosa.com

CNHI/Southeast Iowa

March 15, 2013

Mars was habitable, but no sign of inhabitants

(Continued)

SAM also found the essential ingredients for life, including the elements carbon, hydrogen, oxygen, phosphorus, nitrogen, and sulfur. Those and other elements were found in a range of compounds, some more oxidized than others. That is key, because some microbial life on Earth can tap that range of chemical oxidation states for energy rather than using sunlight for photosynthesis or consuming organic matter.

The search for traces of early life did not hit pay dirt this time around. SAM Principal Investigator Paul Mahaffy of NASA's Goddard Space Flight Center in Greenbelt, Maryland, reported that heating of the drill sample produced some but not all of the chlorinated, single-carbon compounds produced when SAM heated a sample of wind-blown dust. Mahaffy now believes those compounds were derived from vapors of a chemical reagent that SAM carried for another sort of analysis and that had leaked into the sample. SAM operators had the rock sample flushed before heating to remove the contaminant, but some of the chlorinated compounds still showed up, although in smaller amounts. The team has a long way to go before determining whether even this trace carbon came from Mars, Mahaffy says.

Curiosity will be taking another drill sample in the next couple of months. Barring dramatic new findings, it will then start the trek to the foot of Mount Sharp, the pile of enticing rock that drew scientists to Gale crater. The rover's arrival there could come before the end of the year.

This is adapted from ScienceNOW, the online daily news service of the journal Science. http://news.sciencemag.org

 

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