Minuscule traces of cells can be detected in a mineral likely present on Mars, a new study shows. The results, obtained using a technique developed at the U.S. Department of Energy’s Idaho National Laboratory, could help mission scientists choose Martian surface samples with the most promise for yielding signs of life.
INL’s instrument blasts off tiny bits of mineral and looks for chemical signatures of molecules commonly found in cells. While other methods require extensive sample handling, this analysis relies on a “point-and-shoot” laser technique that preserves more of the rock and reduces contamination risk. In the current online issue of the peer-reviewed Geomicrobiology Journal, the researchers report they could detect biomolecules at concentrations as low as 3 parts per trillion.
High sensitivity is crucial for NASA’s search for life on Mars, says INL scientist Jill Scott, whose team collaborated with researchers at the University of Montana-Missoula on the study.
“The worst-case scenario is a false negative,” Scott says. “If you’re just missing stuff, that would be devastating.”
While other techniques also have achieved parts-per-trillion sensitivity, they often require scientists to first extract the organic cell remnants from the mineral. This type of preparation can use up large amounts of sample and potentially introduce contamination.
INL’s method is based on a technique called laser desorption mass spectroscopy. By focusing a laser beam on a spot less than one-hundredth the width of a pencil point, the researchers can knock microscopic fragments off the mineral.
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