Methane on an alien planet could be a sign of geological activity and even extraterrestrial life. Of course, finding out where that methane actually came from could help.
A team of scientists at Australian National University led by Dr. John Moores, an ANU Visiting Fellow from York University in Canada, has started to demystify something about Mars that has eluded scientists for the past decade. The source of methane on the Red Planet used to be a total enigma. Now it is that much closer to being unearthed (at least by robot), because data from the Curiosity Rover and the ExoMars Trace Gas Orbiter (TGO) clued the research team in on where it could be coming from.
"This new study redefines our understanding of how the concentration of methane in the atmosphere of Mars changes over time, and this helps us to solve the bigger mystery of what the source might be," said Moores, whose study was recently published in Geophysical Research Letters.
Aliens that can only be seen under a microscope might be crawling under that mystery and deep beneath the surface of Mars—but back up for just a moment.
Gale Crater (colored to show mineral content in the NASA image above) belches huge amounts of methane. The 3.8 billion-year-old crater is believed to have been the site of an ancient lake before Mars got radiation-bombed and most of its water evaporated. Last year, another research team had discovered that methane concentrations change throughout the course of a Martian day. Moores’ team used the results of this previous work to calculate what he described as “a single number for the rate of seepage of methane at Gale crater on Mars that is equivalent to an average of 2.8 kg per Martian day."
The methane escaping from somewhere under Gale Crater could (theoretically) be released from reactions between water and rocks or decomposing materials we know nothing about yet (which might be the remains of something that was once alive), but what does the presence of this gas have to do with aliens?
"Some microbes on Earth can survive without oxygen, deep underground, and release methane as part of their waste," said Professor Penny King from the ANU Research School of Earth Sciences.
That could mean alien microbes are the source, if they exist.
Humans haven’t walked on Mars yet, so while the team might not have actually trekked through the red dust and seen anything up close, Curiosity and ExoMars have been their eyes. ExoMars’ TGO was designed by the ESA and Roscosmos to seek out evidence of trace atmospheric gases that could be signs of Martian geological—and maybe biological—processes.
The Curiosity and ExoMars findings actually seemed to contradict each other at first. Moores and his team were able to make sense of the different methane concentrations each instrument beamed back by proving that more methane arose during the night, when heat transfer dies down. Finding that out is one more clue that will help lead scientists to the source of all that methane.