Thursday, November 22

Curious about Curiosity

The media are abuzz with speculation about the expected announcement of new results from the Curiosity rover on Mars, at the AGU meeting on Dec. 3. Expectations were fanned to a frenzy by John Grotzinger's comments to NPR's Joe Palca this week, in which he said this would be one for the history books, and would be earthshaking. Needless to say, that has triggered ever-escalating notions of what it might be, from the silly to the superlative and sublime.
What's more likely is that it will indeed be an important announcement, but not of the extreme kind people are thinking of. It's probably not something wriggling or slithering in front of the camera, and it's probably not a fossil, though lord knows I'd be delighted to be proved wrong. Most likely, it's one of two things:
1. Organics in the soil. Ever since the Viking mission in 1976, this has been the biggest bugaboo about life on Mars. No organics were detected by the instrument on that mission, a gas-chromatograph mass spectrometer, that should have found them. That non-detection was taken by most scientists ever since to contradict the results of the labelled-release test, which otherwise would have been seen as a positive detection of living, breathing microbes on Mars. Since then, other tests have demonstrated that fairly abundant organics on Mars could in fact have fallen below the threshold of detection of that GCMS, but the prevailing view for all these years that Viking had failed to find signs of life had become too deeply ingrained for the new evidence to make much of an impression. So, while direct detection of organics in the soil by the much more sensitive instruments on Curiosity would of course not prove the presence of life there now, it would show that the one piece of evidence that had been interpreted as ruling out a positive detection by Viking has now been shown to be false. At the very least, that would open the question anew, and provide a strong impetus to carry out the follow up experiments, which could clinch the matter, and which should have been done long ago.
2. Methane in the air. Though this is also an indirect sign, it too could provide strong evidence for the presence of living, breathing microorganism on Mars today. Curiosity detected signs of methane when it first arrived, but a second set of tests found none, so the initial results were then taken to have been just residual contamination carried there from Earth. But if a third set of tests did find methane again, that would show it had to be Martian after all. And while there are some highly unlikely non-biological mechanisms that could explain methane in the air of Mars, seeing methane that comes and goes would be very, very hard to explain that way. So, like organics, this would be a strong indicator of extant life forms on Mars today.
Either of these findings, while very exciting and likely to cause a turnaround in the prevailing scientific thinking about whether life exists on Mars today, are nevertheless indirect, complex, and likely to remain highly controversial for a long time. But if nothing else, it will finally provide the needed spur for future missions to carry out the tests that would be needed to prove it once and for all.
Or, I could be wrong and the new findings could be something completely different. In any case, we'll know what it is a week from next Monday.


Post a Comment

<< Home