Land Ho! Life on Mars?

M.A. Dworkin

Planet Mars - NASA announced that a sample collected by their Perseverance Mars Rover from an ancient dry riverbed in Jezero Crater on the planet Mars could preserve evidence of ancient microbial life. Taken from a rock named “Cheyava Falls” the sample called “Sapphire Canyon” contains potential biosignatures. 

A potential biosignature is a substance or structure that might have a biological origin but requires more data or further study before a conclusion can be reached about the absence or presence of life. 

“This finding by Perseverance, launched under President Trump in his first term, is the closest we have ever come to discovering life on Mars,” said acting NASA Administrator Sean Duffy. “The identification of a potential biosignature on the Red Planet is a groundbreaking discovery, and one that will advance our understanding of Mars. NASA’s commitment to conducting Gold Standard Science will continue as we pursue our goal of putting American boots on Mars’ rocky soil.”

Scientists believe intriguing leopard spots on the rock may have potentially been made by ancient life. 

“After a year of review, they have come back and they said, listen, we can’t find another explanation,” said Mr. Duffy. “So this very well could be the clearest sign of life that we’ve ever found on Mars, which is incredibly exciting.”

Perseverance came upon Cheyava Falls in July 2024 while exploring the “Bright Angel” formation, a set of rocky outcrops on the northern and southern edges of Neretva Vallis, an ancient river valley measuring a quarter-mile wide that was carved by water rushing into Jezero Crater long ago. 

The Rover’s science instruments found that the formation’s sedimentary rocks are composed of clay and silt, which, on Earth, are excellent preservers of past microbial life. They also are rich in organic carbon, sulfur, oxidized iron (rust), and phosphorus.

The discovery was particularly surprising because it involves some of the youngest sedimentary rocks the mission has investigated. An earlier hypothesis assumed signs of ancient life would be confirmed to older rock formations. This finding suggests that Mars could have been habitable for a longer period or later in the planet’s history than previously thought, and that older rocks also might hold signs of life that are simply harder to detect. 

“Astrobiological claims, particularly those related to the potential discovery of past extraterrestrial life, require extraordinary evidence,” said Katie Stack Morgan, Perseverance’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “Getting such a significant finding as a potential biosignature on Mars into a peer-reviewed publication (Journal Nature) is a crucial step in the scientific process because it ensures the rigor, validity, and significance of our results.”  

The scientific community uses tools and frameworks like the CoLD scale and Standards of Evidence to assess whether data related to the search for life actually answers the question, Are We Alone? Such tools help improve understanding of how much confidence to place in data suggesting a possible signal of life found outside our own planet. 

“Today, we are really showing you how we are kind of one step closer to answering one of humanity’s most profound questions, are we truly alone in the universe?” said Nicky Fox, Associate Administrator for NASA’s Science Mission Directorate.

Since landing on Mars in 2021, Perseverance has crossed Jezero Crater and explored ancient river delta in search of microfossils of past life. The Rover has been collecting samples along the way that were intended to be returned to Earth by future missions. But it is currently unclear how NASA would return the samples to Earth as the agency grapples with the White House’s proposal to slash NASA’s science budget by as much as half. 

Scientists on the project agree that returning the samples is a necessary step in order to ultimately answer the question of whether life has ever existed on the Red Planet.