Three billion year old life on Mars? It’s looking more likely now than ever.

NASA’s Perseverance rover recently found a potential biosignature in a rock on Mars, nicknamed “Cheyava Falls.” Perseverance is exploring the ancient Jezero Crater on Mars, chosen for signs of flowing water there long ago. It was an ancient lake when the Earth was young. Biosignatures are evidence of past or present life on another world, and part of Perseverance’s mission to find life.

This unusual reddish rock, containing a mix of organic molecules and minerals associated with biological processes on Earth, represents the most compelling evidence to date for ancient microbial life on Mars. 

The rocks are mudstones (made in water), dotted with intriguing markings nicknamed leopard spots and poppy seeds. Scientists believe these features contain minerals produced by chemical reactions involving carbon, iron, and water, that could be associated with ancient Martian microbes. For example, Perseverance found Vivianite (hydrated iron phosphate). Vivianite is frequently found on Earth in sediments and peat bogs and around decaying organic matter with microbes. It’s possible the minerals were produced by natural geological processes and not by real Martian microbes, but at a press conference Nasa said the features could be the clearest signs of life ever found on another planet.

“We think what we’ve found is evidence for a set of chemical reactions that took place in the mud that was deposited at the bottom of a lake – and those chemical reactions seem to have taken place between the mud itself and organic matter – and those two ingredients reacted to form new minerals,” explained Dr Hurowitz, lead author of the paper in Nature. Here is the NASA post.

Nature is the most prestigious and thoroughly reviewed science journal. That means the biosignature result is solid science, peer reviewed and facts confirmed. Astrobiological (life on other worlds) claims rarely pass muster, so this publication is an achievement for the JPL team. But what does it mean for life on Mars?

Perseverance used its on-board spectroscopy instruments to date the rocks to 3.5 billion years ago. Here on Earth that was the era where microbial life first began in our oceans. The minerals found are like those on Earth. Could this kind of life have happened on Mars too? Maybe.

Further study in big Earth laboratories are needed to confirm if the sample has a biological origin. The on-board instruments aren’t powerful enough to answer whether the sample is made by life. If it were geologic processes, it would require more heat than we can find at the site. So that’s a point in biologic’s favor. We have to study the sample at JPL to know for certain. A Mars sample return mission has been proposed by Nasa and ESA (European Space Agency), but its future looks uncertain. The government in the United States is making massive cuts to science budgets. So the follow-up studies to confirm the results are on hold awaiting funding.

AGAIN – These Biosignatures are signs that life may have been there, billions of years ago. They are not actual living organisms today. There might be life on Mars today, but we need a sample return mission to answer that question too. If humans go to Mars before we answer these questions, they may never be answered. Once humans arrive, we will bring contamination from Earth life. Right now, Mars is pristine. There could be a new lifeform waiting to be discovered.

The Confidence of Life Detection scale is marked by seven benchmarks, the current report is at Level 3-4. The highest Level yet achieved! A ways to go to before we have proof, but we’re getting closer to finding extraterrestrial life.