On Earth, we take methane for granted. It’s produced by living creatures – such as cattle’s digestive systems and bacteria munching through our refuse in landfills – and geological activity (such as volcanoes and other geothermal processes). In fact, it’s also a rather undesirable byproduct from industry and, if global warming trends continue, we could see vast amounts of the greenhouse gas belching out from the seabed and Arctic permafrost before this century is out. In short, too much methane is very bad for the future health of our planet.
On Mars, however, the presence of methane in the atmosphere is puzzling at best. In 2003, scientists using ground-based observatories to zoom in on the Red Planet detected small quantities (in parts per billion quantities) of methane in the carbon dioxide-rich atmosphere. Not only was the gas found to be globally distributed, in 2009, observations showed that it changed with time.
Intriguingly, methane’s molecular bonds break down very quickly when exposed to ultraviolet light – a form of electromagnetic radiation that Mars’ atmosphere is bathed in. Therefore, Mars methane shouldn’t hang around for long. In fact, from production to chemical break-down, methane should last for approximately 300 years in the Martian atmosphere. The researchers found the gas actually breaks down far quicker than that. The atmospheric methane appears to cycle within one year – meaning that not only does the planet have a voracious methane production mechanism; it also has a voracious methane destruction mechanism. This mechanism can’t only be caused by ultraviolet light, so there must be something else destroying the methane.
During follow-up studies in 2010, Italian researchers using six-years of data from NASA’s Mars Global Surveyor (that was lost in 2006) added some fascinating detail to the Mars methane mystery. They found that methane levels seemed to increase rapidly through the summer months, peak during the autumn and then drop drastically during the winter.
Also, there appears to be several key regions in the Martian northern hemisphere that produce concentrations of the gas: Tharsis and Elysium (locations of Mars’ massive volcanoes), Arabia Terrae (a large upland region that is known to contain large quantities of water ice) and Nili Fossae (a fracture partly filled with sediment). This seasonal variation and discrete regions of methane production is a quandary.