Methane gas is the most abundant natural gas on Earth. It's sources on our planet are attributed to biological, anthropological and geological processes. A recent discovery of methane plumes on Mars has NASA scientists wondering what the source of the methane is: biological or geological. If the source is biological, it could support the theory that there was or is life on Mars. However, many geological processes could also be the source of methane on the Red Planet.
Geological Processes that Produce Methane
Geologic emissions of methane, also referred to as GEM in the scientific community, have long been studied for their role in global climate change. One such study produced a paper in 2007 written by Giuseppe Etiope titled, "Did geologic emissions of methane play any role in Quaternary climate change?" published in the Atmospheric Environment journal. In this paper, Etiope and his colleagues list all the various geological sources of methane on Earth. These sources include:
- Hydrocarbon production in sedimentary basins (biogenic and thermogenic methane)
- Degassing and eruptions of onshore and offshore mud volcanoes
- Diffuse soil microseepage and shallow marine seeps
- Geothermal and magmatic volcano systems
- Natural emissions from coal-bearing rocks
- Degassing from crystalline basement and mantle
These sources contribute a significant amount to the global methane budget - about 100-1,000 tons of methane per square kilometer are injected into the atmosphere annually from GEM sources. Some of these sources, such as emissions from hydrocarbons (fossil fuels), imply that the methane is still related to a biological process at some point - hydrocarbons form from the burial and compaction of bacteria, plants and animals over millions of years. However, other sources, such as the release of methane from crystalline basement and mantle, are completely void of any kind of biological process and are purely geological.
The Source of Methane on Mars
It is difficult right now for NASA scientists to determine exactly what the source is for the methane plumes found on Mars. Without evidence of geological processes such as mud volcanoes and geothermal activities like hot springs on the Martian surface, attributing the source of methane entirely to geologic emissions of methane is difficult.
More data will need to be collected from the surface of Mars, including soil and rock samples, to determine if the methane is seeping through the ground from hydrocarbons. If this is the case, then indeed this could provide more evidence that life did once flourish on this barren planet, but perhaps no more. Another exciting possibility is that the methane emissions are related to geothermal activity that may not be exposed at the surface, but is happening underground. Either way, the presence of methane on Mars has rejuvenated our curiosity and validated what scientists have been saying for years: there is much more to Mars then what we can see on the surface.
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