A multinational group of scientists led by Dr Nigel Blamey of Brock University and the University of Aberdeen, UK, has found methane in fragments of Martian meteorites, a possible clue in the search for life on Mars.
A fragment of the Nakhla meteorite. Multiple fragments of this meteorite were seen to fall as a shower in the hamlets surrounding the village of El-Nakhla in Egypt (near Alexandria) on June 28, 1911. Dr W. F. Hume, Director of the Geological Survey of Egypt, personally visited the site and collected both the evidence of eyewitnesses of the fall and about a dozen specimens including the largest known fragments. The meteorite is thought to have originated from Mars. Image credit: NASA.
Dr Blamey and his colleagues from Canada and UK examined samples from six meteorites of volcanic rock that originated on the Red Planet: the nakhlites NWA 5790, Nakhla, Y 000749, and MIL 03346, and the shergottites Zagami and LA002.
The samples contained gases in the same proportion and with the same isotopic composition as the Martian atmosphere.
All samples also contained methane (CH4), which was measured by crushing the rocks and running the emerging gas through a mass spectrometer.
“The gases released were dominated by CH4, CO2, H2, N2, with traces of O2 and Ar. The highest yields were from Nakhla and LA 002 and lowest from NWA 5790 and MIL 03346,” Dr Blamey and co-authors wrote in a paper published in the journal Nature Communications.
“The CH4/CO2 ratio varies from about 3 (LA002, NWA 5790, MIL 03346) to 23 (Zagami). The H2/CO2 ratio varies from 0.5 to 7. These values are all in the same range as those for terrestrial basalts.”
The researchers also examined samples from two non-Martian meteorites, which contained lesser amounts of methane.
The discovery hints at the possibility that methane could be used as a food source by rudimentary forms of life beneath the Martian surface. On our planet, bacteria do this in a range of environments.
“One of the most exciting developments in the exploration of Mars has been the suggestion of methane in the Martian atmosphere,” said co-author Prof John Parnell of the University of Aberdeen.
“Recent and forthcoming missions by NASA and ESA, respectively, are looking at this, however, it is so far unclear where the methane comes from, and even whether it is really there.”
“However, our research provides a strong indication that rocks on Mars contain a large reservoir of methane.”
Dr Sean McMahon of Yale University, a co-author on the study, added: “other researchers will be keen to replicate these findings using alternative measurement tools and techniques.”
“Our findings will likely be used by astrobiologists in models and experiments aimed at understanding whether life could survive below the surface of Mars today.”
The scientists now plan to expand their research by analyzing additional meteorites.
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Nigel J. F. Blamey et al. 2015. Evidence for methane in Martian meteorites. Nature Communications 6, article number: 7399; doi: 10.1038/ncomms8399
