How Some Clay Shows More Evidence of Past Life on Mars

For almost 9 years, the Curiosity rover has been exploring Mars and been looking for evidence of signs of life. Already, it has found evidence of water erosion, which includes ancient river delts, streams, or craters that could have served as lakes. While Curiosity’s official mission window has ended and more emphasis is being put on Perseverance, Curiosity is still roving around Mars. And it is still making important discoveries on Mars. Curiosity may have just found more evidence that proves that life once existed on Mars.

Curiosity in Gale Crater Captured by
the Mar's Reconnaissance Orbiter

Curiosity made this fascinating and surprising discovery while investigating Gale Crater, a former lake that was created when an asteroid hit Mars about 3.6 billion years ago. Inside Gale Crater, Curiosity found clay-rich sedimentary rocks. Now, you may be thinking, “It's just clay”, but clay is usually created when rocky minerals are weathered away and rot after contact with water, which as you know, is a key ingredient for life. Clay is also known as an excellent material for storing microbial life.

Curiosity took two samples of the ancient mudstone, a sedimentary rock that contains clay. Instead of consisting completely of clay, researchers found that the samples contained only half the expected amount of clay minerals. Instead, there was a higher quantity of iron oxide in the sample, which is just rust. Scientists now believe that the reason this is happening is because of brine. Brine is super salty water that can leak into the mineral-rich-clay layers and destabilize them, which can wipe away geological and biological patches. Curiosity completed its full analysis using its CheMin tool, which is the chemistry and mineralogy instrument. 

Diagenesis

The process that the brine causes is called diagenesis. Scientists believe it could have helped to create microbial life underground and even help to erase microbial life on Mars. But even though this influx of brine wiped out life, there is evidence that brine can also help to create life. Curiosity has done a lot of work in its mission to find evidence that life once existed on Mars. There is even more recent evidence that methane has been found on Mars. If you read this article, you will learn that methane is a good sign of life. Nonetheless, the search for life on Mars will be one of the most important investigations in history and may show that we are not alone.

Curiosity Taking A Selfie in Gale Crater

Sources:

Major, Posted by Jason. “Is Mars Alive? Curiosity Uncovers Organics and Methane in Gale Crater.” Lights in the Dark, 17 Dec. 2014, lightsinthedark.com/2014/12/17/is-mars-alive-curiosity-uncovers-organics-and-methane-in-gale-crater/. 

“Mars Science Laboratory Curiosity Rover - Mars Missions - NASA Jet Propulsion Laboratory.” NASA, NASA, www.jpl.nasa.gov/missions/mars-science-laboratory-curiosity-rover-msl.

Montañez I.P., Crossey L.J. (2018) Diagenesis. In: White W.M. (eds) Encyclopedia of Geochemistry. Encyclopedia of Earth Sciences Series. Springer, Cham. https://doi.org/10.1007/978-3-319-39312-4_35

Turner, Ben. “Curiosity Rover Discovers That Evidence of Past Life on Mars May Have Been Erased.” Space.com, Space, 17 July 2021, www.space.com/mars-life-evidence-erased.