Graphic by Natalie Kulak ’21
BY FIONA HINDS ’21
In the summer of 2013, the European Space Agency’s Mars Express orbiter detected methane emissions in the Gale crater, a large depression near the Martian equator, according to the New York Times. Their findings were later replicated by NASA’s Curiosity rover, which measured levels of methane in the air that lasted for about two months. Methane on Earth is usually produced by living things, so this finding is both exciting and bewildering for scientists, who believe it could potentially indicate alien life. According to Marco Giuranna, a scientist at the National Institute for Astrophysics in Italy and principal investigator of data coming from the Mars Express instrument, these findings are a first. “Our finding constitutes the first independent confirmation of a methane detection,” he said.
Methane in the Martian atmosphere would break up fairly quickly. Taking sunlight and different chemical reactions into account, methane would break up in a few hundred years or so in the thin Martian atmosphere, meaning that any methane measured may have been created recently, which is an exciting prospect.
The source of the methane remains unknown, but scientists have a few hypotheses. It may have been created through serpentinization, a geological process that requires heat and liquid water, and changes rock into a crystal mineral structure. Or theoretically, it could be the byproduct of a lifeform, possibly methanogensm — microbes that release methane as a waste product. Methanogens live in places lacking oxygen, such as underground. Even if the methane is produced by rocks rather than organisms, these hydrothermal systems that produce the emissions are still good locations to search for lifeforms.
Before the summer of 2013, the Curiosity rover detected very little methane in the atmosphere, only around 0.7 parts per billion. During that summer, levels increased by a factor of 10, before falling down to around 1 part per billion the following January. Still, this does not account for the sharp decrease in methane; scientists are still unsure as to how it could be created or destroyed at a rate that fast.
Professor Darby Dyar, a member of the astronomy department and a participating scientist on the Mars Science Laboratory mission, said that she is not going to become overly excited that the methane is from a biological source, even though it’s an interesting idea. “The measurements report very low abundances of methane — only a few parts per billion. On the other hand, the fact that methane comes and goes in the atmosphere indicates some process that is creating it episodically — an idea I find really intriguing,” she said. “My eyes are currently on the next Mars mission, dubbed Mars 2020. It will carry an instrument to look at Raman data of organics in rock and soils, which likely hold the keys to understanding Mars’ past and present habitability.”
Mars is not the only other celestial body where methane has been found. According to NASA, Saturn’s moon Titan has abundant methane on its surface. Because of its distance from Saturn, the average surface temperature on Titan is -290 °F, meaning that methane can exist on the surface in liquid form. There are three methane-rich documented seas with organic-rich compounds on the seabed, which cover roughly two percent of its surface.
There is currently a methane-detecting European spacecraft called the Trace Gas Orbiter that has been orbiting Mars since 2017, but no reports of methane emissions have yet been relayed from this craft. All of this is encouraging evidence to support the hypothesis that Mars is currently a planet home to active lifeforms. More research is needed, and scientists hope for more feedback from crafts such as the Trace Gas Orbiter. The mystery of alien life remains unsolved, but its prospects are increasing.