The presence of methane in the Martian atmosphere has been confirmed by a new analysis of data from the Mars Express probe, researchers said, pointing out that this gas could be an indicator of a micro-organic life or flow from the geological process.
The European Mars Express probe, in orbit around the planet since late 2003, had already detected traces of methane in its atmosphere in 2004 thanks to its infrared spectrometer PFS. But these results had not fully convinced astronomers for technical reasons.
In June 2018, NASA in turn announced that its Curiosity mobile robot had detected methane in the Martian atmosphere five years earlier near the Gale crater. However, these results in situ had raised questions, some wondering if this methane did not come from the robot itself.
In the meantime, the international team led by Italian researcher Marco Giuranna had succeeded in improving the quality of the data collected by the Mars Express infrared spectrometer, a mission of the European Space Agency (ESA).
“We have developed a new approach to select, process and recover data,” from the spectrometer, explains Marco Giuranna. “This largely reduces the uncertainty around PFS measurements,” he adds.
Shortly after Curiosity landed in 2012 in the Gale impact crater, “I decided to conduct a long-term monitoring of the Martian atmosphere” at this location, says the researcher, whose study is published in Nature Geoscience.
On June 16, 2013, a day after Curiosity, the Mars Express spectrometer recorded a “peak emission” of methane above the crater.
These results constitute “an independent confirmation of the measures of Curiosity”, underlines the study.
Finding methane (CH4) on Mars is very important for planetologists because “it could be an indicator of microbial life,” notes the researcher. But the presence of this gas can also result from geochemical reactions, unrelated to life.
The icing on the cake, Marco Giuranna’s team believes to have managed to locate the source of this methane emission in a fault area east of the crater Gale.
The researchers conducted two separate studies, one based on numerical modeling, the other based on a geological analysis of the site. The results of both studies converge on the same area. “It’s very exciting and very unexpected,” enthuses the Italian researcher.
“We have identified tectonic faults that could extend beneath a region covered by a thin layer of ice […] It is possible for the ice to retain subsurface methane and release it episodically when the faults break”, adds Giuseppe Etiope, of the National Institute of Geophysics and Volcanology of Rome