Martian Chemical Complicates NASA Curiosity Rover's Hunt for Life on Mars

A certain chemical may complicate the hunt for life on Mars. It turns that there's a chemical in the Martian soil that interferes with the techniques used by NASA's Curiosity rover to test for traces of life, burning away evidence during tests.

As Curiosity treks across the Red Planet, it checks soil samples and rocks for molecules known as organic carbon compounds. These compounds are the hallmark of living organisms on Earth. In November 2012, though, the rover found evidence of perchlorate, a salt composed of chlorine and oxygen. When Curiosity heats up a scoop of Martian soil to test it for organic carbon, perchlorates can cause a chemical reaction that destroys the carbon.

More specifically, the Curiosity rover's Sample Analysis on Mars (SAM) system tests soil samples by heating them in a pyrolysis gas chromatograph mass spectrometer, which breaks the samples down into their chemical components. This helps scientists determine how much of each of those components is present in the sample.

"The presence of perchlorates isn't good news for some of the techniques we're currently using with Curiosity," said Daniel Glavin, one of the researchers, in a news release. "This may change the way we search for organics in the future on Mars."

Fortunately, though, not all of the organic carbon is destroyed. In fact, scientists estimate that some would survive, which means that they can potentially account for the destroyed carbon. Researchers can assume a certain baseline of perchlorate in the Martian soil, which can allow them to estimate how much organic carbon was present.

"It will be absolutely critical as we move on to other samples to compare them to the Rocknest dune to infer the presence or absence of Martian organic material," said Glavin.

That's not to say that this particular issue will hinder Curiosity in the future, though. The rover has the potential to avoid the perchlorate problem by using techniques that do not involve heating the soil to the point where perchlorates break down. In fact, Curiosity already carries an apparatus capable of that, though it has yet to be used.

The findings are published in the Journal of Geophysical Research: Planets.