As space fans anticipate news of organic molecules from the Mars Curiosity rover 鈥� cryptically teased by the mission鈥檚 chief scientist, John Grotzinger, 鈥� there鈥檚 one man who is even more excited than most.
Former NASA researcher Gilbert Levin says that a positive sign of organics by Curiosity would confirm his claim that NASA has already seen evidence for life on Mars 鈥� from an experiment called Labeled Release that went to the Red Planet aboard the Viking mission.
If Curiosity has found evidence for organics, as many are hoping, 鈥渢hat removes the last barrier to my interpretation of the Labeled Release results, and leaves us free and clear鈥�, Levin told New 杏吧原创.
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Though the prospect of new Curiosity findings have set the internet abuzz, nobody from NASA has yet said publicly what they are: Grotzinger has refused to elaborate, pointing New 杏吧原创, and other journalists, to a presentation scheduled for the American Geophysical Union annual meeting in San Francisco, which begins on 3 December.
鈥楬istory books鈥�
Grotzinger鈥檚 key comment to US National Public Radio 鈥� 鈥渢his data is going to be one for the history books. It鈥檚 looking really good鈥� 鈥� concerned an instrument called SAM, for sample analysis at Mars, which, among other things, is tasked with finding organic molecules in the Martian soil.
Ordinarily, finding organics on the surface would not count as evidence for life, nor would it be surprising, since . But in the case of Mars, it鈥檚 more complicated, says Levin.
That鈥檚 because the failure to detect any organics at all by an instrument aboard the Viking lander was the counter-evidence that cancelled out an apparent detection of active biology by Levin鈥檚 Labeled Release experiment. That experiment showed that radioactively labelled carbon from a nutrient solution added to the soil was released into the air in the test chamber 鈥� an apparent sign of metabolism.
Though Levin has long argued otherwise, the consensus has been that Viking did not find evidence of life on Mars.
Caution urged
Levin acknowledges that, after more than three decades of argument over what the Viking results really mean, opinions are not likely to change overnight, no matter what the new Curiosity results may show. Although proving the presence of organics in the soil will 鈥渞emove all rationale against鈥� his interpretation, he says, 鈥渋t鈥檚 hard to change a paradigm鈥�. Most scientists are convinced that Viking鈥檚 results were inconclusive. 鈥淚 doubt this will change the consensus鈥� he adds.
of the NASA Ames Research Center in Moffett Field, California, is a leading researcher on the possibility of life on Mars, and he, too, urges caution. 鈥淭his is probably not as exciting as the internet rumors suggest,鈥� he says 鈥� as someone who is privy to what Curiosity has found.
Then again, McKay was never convinced that Viking failed to find organics. He has argued, , that the Viking non-detection of organics was invalid, by demonstrating that soils from the Atacama desert in Chile, known to contain organics, showed no signs of them in a test that replicated the one on Viking.
