In 2003, NASA scientists detected traces of methane gas in the atmosphere of Mars. A year later, the Mars Orbiter Rover of the European Space Agency (ESA) confirmed the findings. When NASA sent its Curiosity rover on Mars in 2011, methane was detected again. However, Curiosity was not equipped to differentiate if the found methane, a maximum of 21 parts per billion, originated in a biological or a geological process. The next step of scientists was to send a fully equipped spacecraft that can accurately analyse and identify gases in the red planet’s atmosphere, primarily methane.
In 2016, ESA sent its ExoMars Trace Gas Orbiter for exactly that purpose. Interestingly, TGO found no traces of methane in the Martian atmosphere. This gave birth to a mystery around a gas that could possibly be a sign of life on Mars. On earth, methane is naturally produced either in biological processes - signifying life - or in geological processes - happening in the mantle and coming out of the surface with a volcanic eruption.
Act two of the mystery is more interesting though. Interestingly, the Curiosity rover’s detector Tunable Laser Spectrometer (TLS) kept on detecting methane near the surface. The most surprising thing was if methane was seeping from the ground, it had to dissolve in the atmosphere, and assuming methane was seeping for a long time it should have been to concentrations enough to be detected by TGO.
Then, one of the scientists of the Curiosity team, John E. Moores realized that because Curiosity’s TLS works at night and ExoMars TGO works during the day, the reason for the inconsistency could be somehow methane disappearing quickly as the sun rises. Notably, methane is a gas that is destroyed after 300 years of its generation, which makes the reason for elusive methane quite mysterious and has baffled scientists for a long time.
Now, NASA scientists are conducting experiments to uncover what is destroying the methane on Mars.
“We need to determine whether there’s a faster destruction mechanism than normal to fully reconcile the data sets from the rover and the orbiter,” said Chris Webster, the lead scientist of the TLS, in a news release by NASA. If scientists are able to decode the abundance of natural gas, it could lead them to a potential life flourishing beneath the surface of the red planet.