NASA’s Curiosity rover’s June 2019 detection of methane spikes 3x normal levels in Mars’ atmosphere reignited speculation about subsurface microbial life producing the gas.
The Detection
Curiosity’s Sample Analysis at Mars (SAM) instrument measured methane concentrations of 21 parts per billion - far exceeding the typical 0.5 ppb background. The spike was temporary, dissipating within days. Previous methane detections occurred in 2013 and 2014, showing seasonal variability.
Why Methane Matters
On Earth, 95% of atmospheric methane comes from biological sources - microbes in guts, wetlands, and oceans. Geological processes (like serpentinization, where water reacts with rocks) also produce methane. Mars’ thin atmosphere breaks down methane via UV radiation within 300 years - so ongoing sources must exist.
The Life Hypothesis
Methanogenic microbes thriving in subsurface aquifers could produce seasonal methane releases. Mars has underground ice and potential liquid brines - possible habitats. Plumes might escape through cracks, explaining sudden spikes. But extraordinary claims require extraordinary evidence.
The Geology Alternative
Serpentinization in Mars’ crust could generate methane without biology. Cometary impacts deposit organic material that releases methane when heated. Clathrates (methane ice) might melt seasonally, releasing trapped gas. These explanations require no life.
The Mystery Deepens
The European Space Agency’s Trace Gas Orbiter, designed to map Mars’ methane globally, found almost none - contradicting Curiosity’s ground measurements. The discrepancy is unexplained. Either methane sources are highly localized, measurement techniques differ, or one instrument is wrong.
Future Missions
Perseverance rover (2020) and future sample return missions will search for biosignatures - organic molecules, isotopic ratios, or microfossils. Methane alone can’t prove life exists, but it suggests Mars is geologically or biologically active today, not a dead world.
Source: NASA Curiosity Methane Detection