Strongest signs of life on Mars yet spark debate about a habitable past
A new study led by NASA and including crucial analysis from Imperial College London has sharpened the case for a habitable past on Mars. By examining minerals and organic matter in rocks from the Bright Angel formation in Jezero Crater, scientists say they have identified features that could reflect ancient microbial activity or other biological processes. While these findings do not prove life existed on the Red Planet, they provide a compelling potential biosignature linked to past environmental conditions that were friendly to life.
The Bright Angel outcrop and Jezero Crater: what’s new
The Perseverance rover, a core component of NASA’s Mars 2020 mission, has been exploring Jezero Crater since 2021. The crater’s ancient lake and river delta environments have long been prime targets in the search for past life. In this latest work, researchers focused on a distinctive, light-toned outcrop within Bright Angel, located along the former shoreline of Jezero’s ancient lake in a valley known as Neretva Vallis. The team mapped sedimentary textures and mineral distributions to reconstruct how these rocks were deposited and what they reveal about the ancient environment.
How the science was done: instruments and interpretation
To characterize the rocks, the team used measurements from high-precision on-site instruments carried by Perseverance, including the Planetary Instrument for X-ray Lithochemistry (PIXL) and SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals). These tools map mineralogy and search for organic compounds at tiny scales, helping scientists distinguish lake-margin and lake-bed environments from river-deposited sediments. The analysis showed a sedimentary suite rich in silica and clays—minerals that typically settle in quiet, low-energy waters—contrasting with what is expected from fast-flowing rivers that transport fine particles away.
Lake deposits at the bottom of a river valley
One of the study’s striking conclusions is that the Bright Angel rocks likely record lake deposits at the bottom of a river valley, rather than a straightforward river channel. This interpretation suggests a period when the valley was flooded, creating a shallow, stable environment with conditions that could support microbial life. Co-author Alex Jones, a PhD researcher in ESE and a collaborator with the Perseverance team, commented on the finding: “This is unusual but very intriguing, as we wouldn’t expect to find such deposits in Neretva Vallis. What our sedimentological and stratigraphic work has done is indicate a past, low-energy lake environment – and that is precisely the kind of habitable environment we have been looking for on the mission.”
Implications for life and what comes next
The authors stress that identifying a potential biosignature is an important step, but it is not definitive proof of past life. Professor Sanjeev Gupta, a leading Earth scientist at Imperial’s Department of Earth Science and Engineering, emphasized the cautious tone: “This is a very exciting discovery of a potential biosignature, but it does not mean we have discovered life on Mars. We now need to analyse this rock sample on Earth to truly confirm if biological processes were involved or not.” The researchers also highlight that Perseverance’s mission is to collect carefully selected rocks and store them for later return to Earth, where even more comprehensive analyses can be conducted with a wider suite of instruments.
Why this matters for Mars exploration
These findings reinforce the scientific case that Jezero Crater hosted environments suitable for life long ago. They also illustrate how geological context—such as deposits formed in calm, low-energy waters—can create robust biosignatures that are detectable remotely and on-site before a sample return. The work underscores the importance of the mission’s strategy: gathering pristine rock samples from ancient lake settings and ensuring their preservation for future, more detailed study on Earth.
Looking ahead
As NASA’s Perseverance continues to traverse Jezero’s valley floors, scientists will refine their reconstruction of the lake’s history and its potential for hosting life. The prospect of a past habitable environment in Jezero Crater remains a key thread in the broader search for life beyond Earth—and a reminder that Mars still holds many clues about its enigmatic past.
