PASADENA, Calif. – The Curiosity rover on Mars has made a surprising discovery, detecting methane seeping from the surface of Gale Crater, raising questions among scientists about the source and behavior of the gas. While methane is predominantly produced by living organisms on Earth, the lack of current or ancient life signs on Mars has puzzled researchers.
The rover’s portable chemistry lab, known as Sample Analysis at Mars (SAM), has consistently found traces of methane near the surface of Gale Crater, the only place on Mars where methane has been detected so far. Scientists believe that the geological mechanisms involving water and rocks deep underground might be responsible for the gas emissions.
Further complicating the mystery is the unusual behavior of methane in Gale Crater. The gas appears at night and disappears during the day, showing seasonal fluctuations and occasional spikes to levels significantly higher than normal. Notably, methane does not accumulate in the Martian atmosphere, with the European Space Agency’s ExoMars Trace Gas Orbiter detecting no methane.
Researchers have proposed a theory suggesting that methane, regardless of its source, could be trapped beneath solidified salt formations in Martian regolith. The seal of salt potentially cracks under specific conditions, allowing methane to seep out, providing a possible explanation for methane detection only in Gale Crater.
Led by planetary scientist Alexander Pavlov at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the research team conducted experiments using permafrost samples infused with a Mars-like salt called perchlorate. The results indicated that the formation of salt seals under Mars-like conditions may facilitate the release of methane.
This hypothesis originated from a previous experiment led by Pavlov in 2017, involving the growth of microorganisms in simulated Martian permafrost infused with salt. The team noticed the formation of a salt crust when the salty ice sublimated, leaving the salt behind, sparking further investigation into methane emissions on Mars.
Continued research and theoretical work are crucial to understanding methane generation and destruction processes on Mars, aligning with recommendations from the 2022 NASA Planetary Mission Senior Review. However, researchers emphasize the need for more consistent methane measurements across the planet to unravel the methane mystery on Mars.
Despite the challenges, scientists remain committed to exploring the unique behavior of methane on Mars, with the ultimate goal of unlocking the secrets of the Red Planet’s methane emissions. The ongoing research efforts aim to shed light on the geological and environmental conditions that could influence methane presence on Mars.