Overview
- A peer-reviewed paper published in September 2026 reports that Perseverance’s in-situ measurements identify at least three separate water-related alteration episodes in the Margin Unit at the inner rim of Jezero Crater.
- The finding is based on more than 185 bedrock analyses by the rover’s SuperCam laser spectroscopy instrument, which revealed that the Margin Unit is igneous rather than sedimentary and preserves crystal-scale records of later fluid change.
- The team reconstructed a sequence of events: CO2-rich groundwater reacting with olivine to form carbonate-filled fracture ridges, a later lake- or groundwater-linked episode that left silica in rocks below the former waterline, and a still-later hot subsurface event that produced calcium-sulfate and fluorite veins.
- Those alteration reactions matter for habitability because olivine-water chemistry can release hydrogen, a potential microbial energy source, and because carbonate and silica are good at preserving chemical traces of past life.
- The study revises orbital-based interpretations of Jezero, leaves the absolute ages of the alteration events unresolved, and makes the Margin Unit and its cached samples high priorities for targeted sample-return and follow-up lab dating.