NASA scientist John Grotzinger got himself in hot water when he said the Mars Curiosity team had “some exciting new results,” that was “one for the history books.” NASA quickly downplayed the whirlwind of speculation that arose, and yesterday released their results.
Although Grotzinger has not clarified the reason for his comments, it seems there are two points that could have generated his excitement. The first is that the ratio of water in the sample was higher than expected.
Given the arid nature of the Martian landscape, its low temperatures and low atmospheric pressure, sitting right at the triple-point of water (which means water ice sublimates into a gas without becoming liquid), even a small percentage of dust-bound water molecules is surprising, and bodes well for the notion that Mars may once have been a wet planet. That this could be detected in a drift of loose sand particles is remarkable.
More than likely, though, Grotzinger’s excitement came from the SAM instruments detecting complex carbon molecules, but these are thought to have originated on Earth.
Given the fastidious sterilisation procedures Mars Curiosity was put through, where components were assembled in a clean room, subject to alcohol swabbing, baking at extreme temperatures beyond the limits of microbial survival, etc, this finding highlights just how astonishingly sensitive the Curiosity instruments are.
Bacteria are surprisingly persistent and robust, more so than most people would realize. The average human carries somewhere in the order of 200 trillion microbes. It is practically impossible to completely sterilize a probe like Curiosity, but it was cleaned to an estimated 300,000 microbes across the entire space craft, which is considerably cleaner than your kitchen bench.
The good news is, such a high degree of sensitivity in the Mars Curiosity SAM package may have triggered a false-positive this time around, but it also confirms the design as being capable of detecting organics at the lowest of levels.
Rocknest may not have delivered “one for the history books,” but Mars Curiosity is on track to revolutionize planetary science. Grotzinger may have been over-enthusiastic, but that’s a wonderful trait to have in exploration.