Since it landed on the Red Planet, NASA’s Curiosity rover has been exploring the Gale crater in search of clues that will explain how the Martian landscape has changed over time. The rover has now identified a spike of methane in the atmosphere of Mars, corroborating previous elusive observations of methane that could not be readily explained for decades. While this certainly does not imply evidence of life, the discovery of organic molecules is pretty exciting and will help guide future studies of the Martian atmosphere. The results of the study were published in Science.
The study utilized readings obtained over the course of almost two years using the Sample Analysis at Mars instrument suite’s tunable laser spectrometer. The average methane concentration is fairly stable at 0.7 parts per billion by volume (ppbv), though there were spikes that brought the amount up to 7 ppbv. This fluctuation is about ten times greater than normal, which is particularly odd given that computer modeling of atmospheric methane predicted that it would have been fairly uniform.
Along with methane concentration, the researchers also used a suite of instruments to measure and correct for humidity, temperature, and fluctuations in the atmosphere. Ultimately, they found that these spikes of methane persisted.
"Within this context, and when we were all almost fully persuaded that the data we had so far collected were at the very least rough it not fully invalid, the expectations to decide on this were bestowed upon the capacity of the SAM instrument to come up with more precise measurements,” co-author Francisco Javier Martín-Torres from the University of Granada said in a press release.
Methane is a common byproduct of biological processes, but that is not the only way it is created. The presence of methane alone is not enough to say that life exists, or once existed, on Mars. However, it is still not clear where the methane is coming from. Future research will need to determine the origin of the methane as well as further investigate why it has spikes in certain areas.
“It is a finding that puts paid to the question of the presence of methane in the Martian atmosphere, but it does pose some other more complex and far-reaching questions, such as the nature of its sources—which must lie, we believe, in one or two additional sources that were not originally contemplated in the models used so far. Among these sources, we must not rule out biological methanogenesis,” Martín-Torres concluded. “Another new question is related to the bizarre evolution of methane in the Martian atmosphere after its emission. Both questions should be addressed in the future with specifically designed new research.”