Methane, one of the signs suggesting extraterrestrial life, has been discovered in an unexpected way by the Curiosity rover.
A recent study published in the Journal of Geophysical Research: Planets has provided an explanation for why a mobile chemical laboratory aboard NASA’s Curiosity rover continuously detects traces of “life gas” methane (CH4) from the surface of Gale Crater on Mars.
Gale Crater landscape being surveyed by the Curiosity rover – (Graphic: SCITECH DAILY).
Curiosity, resembling the famous animated character Wall-E, is NASA’s robotic rover that has been operating on Mars since August 2012 with the mission of searching for signs of life.
This fortunate robot was the first to discover the existence of “building blocks of life” on the red planet.
However, evidence since then suggests that Mars appears to be lifeless, and NASA mainly hopes to gather evidence of ancient life.
Therefore, when the mobile laboratory SAM located within Curiosity analyzed samples from Gale Crater—a primordial impact crater—and continuously found evidence of methane escaping, the scientific community was puzzled.
Curiosity Rover – (Photo: NASA).
Living organisms produce most of the methane on Earth. Thus, methane has long been regarded as a potential sign of life that astrobiologists are still striving to detect in the spectra of other planets.
However, in Gale Crater or anywhere on Mars, no instruments have detected any living organisms. Therefore, NASA did not expect to find methane here.
“It’s a story with many surprising twists,” revealed scientist Ashwin Vasavada, a member of the Curiosity operations team at NASA’s Jet Propulsion Laboratory (JPL).
Collaborating with researchers from NASA’s Goddard Space Flight Center, they developed new models indicating that the unusual source of methane could be related to geological processes involving water and deep rock underground.
This gas could be trapped beneath a layer of salt formed in the Martian regolith, a type of “soil” made from rock and fine dust.
As temperatures rise during warmer seasons or times of the day, the salt layer weakens, allowing methane to escape.
Additionally, this gas could also be expelled in bursts when something heavy presses down on the ground—in this case, the wheels of the SUV-sized Curiosity rover.
However, at another impact crater named Jezero Crater, where NASA’s equally heavy rover Perseverance is operational, no methane has been detected escaping in the same manner.
This discovery may indicate that the environments in these two areas are different. Furthermore, the way methane appears and gets buried under Martian “soil” remains an intriguing subject for exploration. Understanding this could provide insights into the ancient Martian environment and help scientists get closer to evidence of potential extraterrestrial life—even if that life has since gone extinct.
