The Mystery Of The Missing Methane On Mars Continues To Deepen

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The methane that once existed on Mars appears to be missing now and scientists are baffled. While the Mars Express orbiter showed that there were traces of methane in the red planet’s atmosphere back in 2004, according to findings by a European satellite, it all appears to have vanished now. If it does turn out that there is no longer any methane on the red planet, this could spell bad news for the microbes that scientists thought might be creating this gas.

As Science Magazine reports, the Mars Express orbiter measured the level of methane on Mars at 10 parts per billion (ppb), and some scientists have now suggested that the instruments on this spacecraft may not have had the right amount of sensitivity to have accurately gauged the precise amount of methane present.

However, the NASA Curiosity rover also detected methane at 7 ppb when it was perched in the Gale Crater of Mars, and this presence continued for many months after it was discovered. After this, scientists found that there was something called a minute seasonal cycle which led to the measurement of 0.7 ppb of methane during the summer in the north of the planet.

In an effort to better understand what is going on with this mysterious methane on Mars, in 2016 the European Space Agency’s Trace Gas Orbiter (TGO) devotedly scanned the atmosphere of Mars for this gas. Belgian and Russian instruments were created so that even extremely low amounts of methane could be picked up, but as NOMAD’s principal investigator Ann Carine Vandaele has noted, “We already know we can’t see any methane.”

As the Trace Gas Orbiter continues to look for methane on Mars, scientists have explained that so far it has not detected any, even when searching all the way down to 50 parts per trillion. Chris Webster, a planetary scientist at the Jet Propulsion Laboratory in Pasadena, California, that is responsible for running the instrument on Curiosity that seeks out methane, was certain that the TGO would at least be able to receive a signal of 0.2 ppb. However, Webster remains cautiously optimistic and notes that his team spent six months in total working on detecting the original methane spike.

“I’m confident that over time there will be a consistency between the two data sets.”

NASA’s Curiosity team have surmised that the cycle of methane may very well be a product of micro-seeps from within the subsurface of Mars and that these are more likely to come from either geological sources or ones that may even be living, instead of sources that lurk outside the red planet. As Webster stated, “The methane is not coming from above. That’s a big result.”

While scientists believe that the Gale Crater is almost certainly not the only location on Mars that has these micro-seeps, University of Michigan planetary scientist Sushil Atreya has noted that even if there were thousands of these seeps, the amount picked up and traced would still be extremely small.

“I actually did the calculation. It’s going to average out to be a very, very low value, non-detectable.”

Fortunately for everyone who would like the mystery of the missing methane on Mars to be solved, the TGO will continue working on this project until 2022, and scientists may yet be able to determine whether microbes exist within Mars that are causing this methane to flare up and be detected.