Curiosity finds ‘complex chemistry’ in Martian soil

Two of the scoop marks in the sand drift called Rocknest, where samples were taken for analysis. Credit: NASA / JPL-Caltech / Malin Space Science Systems

After a couple of weeks filled with rumour and speculation, the much-anticipated latest findings from the Curiosity rover were presented yesterday morning at the American Geophysical Union (AGU) meeting in San Francisco. So, has Curiosity found organics yet or not?

The answer is, well… maybe.

The rover is searching for organics using its Sample Analysis at Mars (SAM) on-board laboratory. As SAM Principal Investigator Paul Mahaffy puts it, “We have no definitive detection of Martian organics at this point, but we will keep looking in the diverse environments of Gale Crater.”

NASA had downplayed the rumours swirling around the internet in the last few days before the press conference, explaining that the original reports of complex organics or possibly even something more interesting being found already were false and a misinterpretation by the NPR reporter.

Today’s announced results confirmed that, but that is not to say that they are not interesting.

To be accurate, there is a hint of possible organics, but it is going to take more analysis to confirm this (or not). Hence the word “definitive” being used by Mahaffy.

Water (in the form of bound molecules), sulfur, chlorine and oxygen have been identified so far, in the soil samples taken from the sand drift called Rocknest. This is thought to be “ordinary” Martian sand, blown about by the wind and common all over the planet.

Chlorinated methane compounds were also found, although these are thought to probably be the result of the perchlorate being heated inside the test chamber and reacting with other chemicals. One of those chemicals though is carbon; in this case, simple one-carbon organic molecules.

There’s that word again, organics. The carbon compounds tentatively discovered still have to be verified by further testing, and it isn’t known yet whether they originate from Mars itself, meteorites or the rover. The chlorine however is thought to be distinctly Martian.

The chlorine and oxygen may originate from perchlorate, a reactive chemical which can destroy organic compounds, and has been found before on Mars, by the Phoenix lander near the north pole.

In short, there is a lot of chemistry going on in this small patch of “ordinary” soil, and it will take time to figure it all out. The really interesting stuff though should come from the rock samples which will be drilled into in the near future. This is where any organics could be preserved, or deeper underground.

Until then, we will just have to be patient, as it takes time for science to be done properly. And as others have pointed out, just the fact that there is a highly advanced laboratory the size of a car roaming around on an ancient streambed on Mars right now, and working virtually flawlessly, is amazing in itself.

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