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Mars yields a new mystery: Where has all the methane gone?

A super-sensitive Mars probe has failed to detect any methane above the planet, which is not what scientists expected.
A super-sensitive Mars probe has failed to detect any methane above the planet, which is not what scientists expected. A super-sensitive Mars probe has failed to detect any methane above the planet, which is not what scientists expected.

First results from the UK-backed ExoMars mission to the Red Planet have mystified scientists.

The Trace Gas Orbiter (TGO) that stationed itself 400km (248.5 miles) above Mars in April last year was expected to detect methane, a potential bi-product of life.

But even though the gas has been spotted on several previous occasions, both on the planet’s surface and in its atmosphere, none was found.

TGO’s super-sensitive chemical analyser is capable of detecting methane at levels up to 100 times lower than were previously possible.

It can also identify the type of carbon in methane – which could tell scientists whether the gas was likely to have been produced by geology or Martian bugs.

Dr Manish Patel, from the Open University, who is in charge of the Nomad chemical analysis instrument on TGO, said: “The measurements we have made are very surprising. The methane previously detected by ground-based telescopes, the ESA (European Space Agency) Mars Express spacecraft and the Nasa Curiosity rover seems to have disappeared.

“Mars continues to confound us. The only way these results make sense with previous observations is if there is a new mechanism in the atmosphere, removing the methane at a rate far faster than thought possible.

“As always, Mars provides us with another mystery to solve.”

The new findings were published in the journal Nature and presented at the European Geosciences Union meeting in Vienna.

A “spike” of methane detected on the Martian surface by the Curiosity rover on June 16, 2013, was picked up the next day by the Mars Express orbiter.

Illustration of the Curiosity rover
Illustration of the Curiosity rover The Curiosity rover Methane was detected by the Curiosity rover (NASA/JPL-Caltech)

Scientists traced the methane “burp” to a region near Gale Crater, a 96-mile-wide bowl where Curiosity landed in 2012 and which may be the site of an ancient lake.

Writing in the journal Nature Geoscience earlier this month, they said it was likely the methane had bubbled up through cracks in surface ice.

The discovery left open the question of whether the gas was produced by geological or biological processes.

Confirmation that methane is spouting from the Martian surface in at least one location makes it all the more extraordinary that none was found by TGO.

ExoMars is a two-part mission. The TGO will be joined in 2021 by the British-built Rosalind Franklin rover, now under construction by Airbus in Stevenage.

The rover will be able to probe under the Martian surface for signs of past or present life.

Sue Horne, head of space exploration at the UK Space Agency, said: “ExoMars embodies the best of UK and European space science and I’m delighted that Britain is one of the biggest supporters.

“This data release is the first of many on our mission to unearth the mysteries of the Red Planet. The results both answer, and raise new questions, paving the way for more exciting discoveries from the Rosalind Franklin rover which is due to launch next year.”

Other results from TGO, also published in Nature, describe the impact of a massive global dust storm that has enveloped the Red Planet.

The spacecraft monitored the storm from the moment it began and studied how the dust affected water vapour in the atmosphere.

Britain is a major contributor to ExoMars mission. The UK Space Agency has invested £248 million to the overall ExoMars mission and £12 million to its instruments.