The sulphur-containing molecule methyl mercaptan is naturally produced in significant quantities on Earth only by microbes, including some that make their pungent presence known in the human body. NASA's next Mars rover is highly sensitive to the smelly chemical, which could betray the presence of Martian microbes, says Steven Vance of NASA's Jet Propulsion Laboratory in Pasadena, California.
The instrument in question is the Tunable Laser Spectrometer, which will fly on the Curiosity rover - set to land on Mars in 2012. TLS was designed to analyse the carbon isotopes in Mars's methane to search for signs that the gas has a biological origin. But the isotope tests might produce ambiguous results, so finding methyl mercaptan would help bolster the case for Martian microbes, Vance says. TLS should be able to detect the gas at concentrations below 100 parts per billion, according to his team's tests on a similar spectrometer (Planetary and Space Science, DOI: 10.1016/ j.pss.2010.08.023).
