NASA will search for signs of life on Mars with a giant rover due to launch in 2009. The agency selected the vital instruments that the Mars Science Laboratory rover will carry on Tuesday.
Scientists have long debated whether life ever blossomed on our neighbouring planet. NASA’s twin Viking landers beamed back contradictory evidence for biological activity after they touched down in 1976. But since then, the agency has not searched directly for signs of life but for the conditions and substances that support it, such as water.
Now, NASA is planning a rover with three times the mass (600 kilograms) and twice the number of instruments (10) as those currently on Mars, the long-lived Spirit and Opportunity. These use remote sensing and instruments that can scratch away surfaces to analyse the geology of the Red Planet. But MSL will contain two “laboratories” in which samples can be collected, crushed and analysed.
One is a 30-kilogram package of tools called the Sample Analysis at Mars (SAM) that includes an updated version of an instrument first flown on the Viking mission. Called a gas chromatograph mass spectrometer, it segregates molecules according to their mass, then identifies them. It will be able to search for the patterns of carbon isotopes that on Earth tend to be produced by life.
Terrestrial microbes contain more carbon 12 than carbon 13 when compared to inorganic material, says Paul Mahaffy, principal investigator for SAM at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Frank Palluconi, MSL project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, agrees. “If you find organic compounds, this is a way to try to decide if they were made biologically or not,” he says. “It wouldn’t be completely definitive, but it would be a strong clue.”
SAM will also study Mars’s atmospheric methane to try to tease apart whether it is formed by life or by a geological process. MSL will operate for one Mars year – the equivalent of two Earth years.
“So any change you might see in methane over that time period or even in the direction the wind is blowing might give a clue about its source regions,” Palluconi told New Scientist.
The other laboratory, called CheMin, will analyse the composition of minerals on Mars, which can reveal information about the conditions in which they formed. Spirit and Opportunity do this, but they use a technique that only works for minerals containing iron.
CheMin’s X-ray diffraction method will be able to analyse all minerals. Other instruments include high-resolution cameras and a detector to map the surface radiation that might endanger any future astronauts.
There will be so many instruments packed onto the rover, in fact, that engineers think it is too massive to land with airbags. They are developing a new design in which the rover will be hung from a frame that is fitted with thrusters.
After initially slowing down with a parachute, the thrusters would stabilise the rover so it was hovering just above the planet’s surface. Then they would gently set it down on its wheels and release it.
Many such technical issues – and even the landing site – still need to be worked out. But if all goes as planned, NASA will build the rover with a budget of $900 million and launch it in December 2009.
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