In a groundbreaking discovery that reshapes our understanding of the Red Planet, NASA's Perseverance rover has provided compelling evidence that Mars' Jezero Crater was not just once, but multiple times, a site of significant water activity. Each of these distinct wet periods held the potential to support life, marking a major leap forward in the search for extraterrestrial life.
From Harsh Beginnings to Habitable Environments
Scientists analyzing high-resolution geochemical data from the rover have identified an astonishing 24 different mineral types on the crater floor. This mineral diversity reveals a planetary surface chemistry that evolved over time, mirroring the changes seen in Earth's own ancient oceans. The findings, published in the Journal of Geophysical Research: Planets, paint a picture of a Mars that transitioned from harsh, inhospitable conditions to environments increasingly favourable for life.
The research team, led by Eleanor Moreland, a graduate student at Rice University, utilized the Mineral Identification by Stoichiometry (MIST) algorithm to interpret data from the rover's Planetary Instrument for X-ray Lithochemistry (PIXL). This instrument uses X-rays to determine the precise chemical makeup of Martian rocks, delivering some of the most detailed off-Earth geochemical analyses ever conducted.
A Three-Stage Geological History
The study categorizes the geological history of Jezero Crater into three primary stages, each defined by its water chemistry.
The first and earliest phase was the most extreme, involving high-temperature, acidic waters. These harsh conditions produced minerals like greenalite, hisingerite, and ferroaluminoceladonite. While such an environment would have posed severe challenges for life, co-author Kirsten Siebach noted that the resilience of microbes in Earth's extreme environments, like Yellowstone, suggests life could have potentially adapted even then.
The second stage brought a significant shift to milder, neutral conditions that were far more conducive to life. This period is marked by the presence of minerals such as minnesotaite and clinoptilolite.
The final phase saw the emergence of cooler, alkaline fluids that formed sepiolite. This created conditions that were especially favourable for habitability and signalled a substantial and widespread presence of liquid water across the examined regions of the crater.
Implications for the Search for Life
According to Moreland, the mineral transitions in Jezero Crater trace a clear and compelling progression. Mars evolved from acidic to neutral and finally to alkaline environments, showing a planetary chemistry that was moving towards conditions that could support life as we know it.
To ensure the accuracy of their findings, the team employed a sophisticated propagation model, similar to those used in hurricane forecasting, to account for analytical uncertainty. This rigorous approach not only supports the core scientific goals of NASA's Mars 2020 mission but also builds a crucial mineralogical reference for future analyses of samples returned to Earth.
These findings confirm that Jezero Crater, which was once an ancient lake, underwent complex, water-driven transformations over its long history. The newly identified minerals are key to evaluating the potential for past life on Mars and will directly guide Perseverance's ongoing sample collection for future return missions. While this study focuses on data from the rover's first three years, it provides essential context, indicating that the life-friendly conditions observed more recently likely existed broadly across the crater.
The research was supported by NASA’s Mars 2020 Participating Scientist grants, the Jet Propulsion Laboratory, and the Mars Exploration Program.
