Mystery of Methane Seepage in Mars' Gale Crater: A Surprising Discovery by NASA's Curiosity Rover

NASA's Curiosity Mars Rover recently made a shocking discovery - methane gas is seeping from the surface of Gale Crater on Mars. This revelation took scientists by surprise, as there have been no signs of current or ancient life on Mars, and methane is predominantly produced by living organisms. The Sample Analysis Mars (SAM) instrument, a portable laboratory on Curiosity, detected traces of methane near the surface of Gale Crater.

In contrast, the European Space Agency's ExoMars Trace Gas Orbiter found no methane in the atmosphere of Mars. This discrepancy raises questions about the source of the methane and why it is only present in Gale Crater. Researchers believe that geological mechanisms involving water and rocks deep underground may be responsible for the presence of methane in Gale Crater.

The gas exhibits unusual behavior, appearing at night and disappearing during the day, fluctuating seasonally, and sometimes spiking to levels 40 times higher than usual. In a recent paper published in the journal Geophysical Research: Planets, a NASA research group proposed a theory to explain the unexpected presence and behavior of methane in the Gale Crater. According to the study, solidified salt in the Martian regolith could be sealing methane underneath the surface.

As temperatures rise during warmer seasons or times of day, the sealed methane could seep out, causing fluctuations in methane levels. Alexander Pavlov, a planetary scientist at NASA's Goddard Space Flight Center, led the research that suggests methane eruptions may occur when the seals crack under pressure, possibly triggered by the movement of a small rover like Curiosity. The research builds on an experiment conducted in 2017, where microorganisms were grown in simulated Martian permafrost infused with salt.

Although the results of the microbe-growing experiment were inconclusive, researchers observed the formation of a salt crust on the soil surface as salty ice sublimated. In the experiment, five samples of permafrost infused with different concentrations of perchlorate, a salt commonly found on Mars, were exposed to varying temperatures and air pressure in a Mars simulation chamber. Neon, a methane analogue, was periodically injected underneath the soil samples, and the gas pressure below and above the surface was measured.

The results showed that a seal formed under Mars-like conditions within three to 13 days in samples with five to ten percent perchlorate concentration, trapping the gas underneath the surface. While this experiment provided insights into how methane could be sealed beneath the Martian surface, the concentrations of perchlorate detected by Curiosity in Gale Crater were much higher, indicating that further research is needed to fully understand the methane seepage in Gale Crater. Overall, the discovery of methane seeping from the surface of Mars presents a new mystery for scientists to solve.

The unexpected presence and behavior of methane in Gale Crater raise questions about the geological and chemical processes occurring on the Red Planet and could provide valuable insights into its past and potential habitability. As NASA's Curiosity Rover continues its exploration, more discoveries are sure to come, further expanding our understanding of Mars and its enigmatic methane emissions.