Washington: An investigation has revealed that perchlorate - a salt comprising of chlorine and oxygen - causes the evidence of life to burn away during the tests.
In search of clues to life`s presence - now or in the past - Mars rover Curiosity tests Martian soil and rocks for molecules known as organic carbon compounds - hallmark of living organisms on Earth.
While trekking around the Rocknest sand dune in November 2012, the rover found evidence of perchlorate. When Curiosity heats a scoop of Martian soil to test it for organic carbon, perchlorates can cause a chemical reaction that destroys organic carbon.
Daniel Glavin, an astrobiologist at NASA`s Goddard Space Flight Center in Greenbelt, Maryland, and first author on the new paper, said that he believes that the troublesome perchlorates are likely to be prevalent throughout the surface of Mars.
The Curiosity rover`s Sample Analysis on Mars (SAM) system tests soil samples by heating them in an instrument, called a pyrolysis gas chromatograph mass spectrometer, which breaks the samples down into their chemical components and determines precisely how much of each of those components is present in the sample.
Any perchlorate salts in the heated sample decompose as the temperature goes above 200 degrees Celsius (392 degrees Fahrenheit) and release pure oxygen. Organic molecules in the sample exposed to this oxygen will then combust into carbon dioxide, destroying the molecular evidence of their presence.
The study has been published in Journal of Geophysical Research.