Scientists find likely source of methane on Mars

The mystery of methane on Mars could finally be solved, scientists confirmed Monday the presence of the indicator gas of life on the red planet and its origin.

In the 15 years since a European probe has reported traces of gas in the Martian atmosphere, the accuracy of readings indicating methane, produced on Earth by simple life forms, has made the ## 147 ## 39, subject of lively discussions.

Since methane dissipates fairly quickly – after about 12 years on Earth – and because of the difficulty of observing Mars' atmosphere, many scientists have questioned previous studies based on a single dataset.

At present, an international team of experts has compared the observations of two spacecraft separated, spaced just one day in 2013, to find independent evidence of methane on the neighboring planet.

In addition, they conducted two parallel experiments to determine the most likely source of methane on Mars as being an ice cover east of Gale Crater, itself supposed to be a long dry lake.

"It's very exciting and largely unexpected," said Marco Giuranna, of the National Institute of Astrophysics in Rome.

"Two completely independent lines of investigation have highlighted the same general area of ​​the most likely source of methane."

The European Mars Express spacecraft measured 15.5 parts per billion in the atmosphere above Gale Crater on 16 June 2013. The presence of methane in the vicinity was confirmed by readings taken 24 hours earlier by the NASA's Curiosity robot.

Using the data, Giuranna and the team divided the area around the crater into 250 km2 grids.

One study then carried out a million computer-generated emission scenarios for each section, while another team studied images of the planet's surface in search of Earth-related features. with the release of methane.

& # 39; Life Indicator & # 39;

The most likely source was a layer of frozen methane beneath a rock formation, which, according to the team, periodically releases gas into the atmosphere.

Giuranna said that although methane is a sign of life on Earth, its presence on Mars is not necessarily evidence of something similar on the red planet.

"Methane is important because it could be an indicator of microbial life," he said. "But life is not necessary to explain these detections because methane can be produced by abiotic processes."

"Although it is not a direct biosignature of life, methane can add to the livability of Martian environments because some types of microbes can use methane as a source carbon and energy, "he added.

Although there is no liquid water on Mars, the European Space Agency said in February that its imagery equipment had shown new signs of "cold weather". drying up of riverbeds, suggesting that the red planet may have already hosted simple organisms.

Giuranna said additional research was needed to determine the extent of the methane ice sheet near Gale Crater.

If the methane it contains is vast, it contains "could support a sustainable human presence" on Mars, as a possible source of fuel for industrial processes and thruster for the return of inhabited missions to Earth, he said. declared.

The study is reported in Nature Geoscience this week.

© 2019 AFP