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Unusual minerals and organics discovered in Jezero
NASA’s Perseverance rover has identified an uncommon suite of chemical and mineral patterns in the Bright Angel formation of Jezero Crater that may represent some of the most compelling potential biosignatures on Mars to date. The rocks contain organic carbon together with iron, sulfur and phosphorus in spatial arrangements reminiscent of microbially driven redox cycling on Earth.
Rocks in the Bright Angel Formation. NASA’s Mars Perseverance rover acquired this image using its Right Mastcam-Z camera. Mastcam-Z is a pair of cameras located high on the rover’s mast. This image was acquired on May 29, 2024 (Sol 1164) at the local mean solar time of 12:40:40. Credit: NASA/JPL-Caltech/ASU
Field context and analytical methods
The Bright Angel formation sits in the Neretva Vallis channel within Jezero and is dominated by mudstones and layered sedimentary beds deposited in ancient standing and flowing water. Perseverance used instruments such as SHERLOC (a Raman and fluorescence spectrometer) and PIXL (an X-ray fluorescence microprobe) to map organic molecules and fine-scale mineral distributions.
Perseverance rover reached the Bright Angel site on Mars by navigating through a dune field, bypassing large boulders. The rover is now investigating this area’s unique geological features to understand Mars’ past environmental conditions and support future human exploration. Credit: NASA/JPL-Caltech
Mineral indicators and textures
Scientists reported tiny nodules and “reaction fronts” — nicknamed “poppy seeds” and “leopard spots” — enriched in ferrous iron phosphate (likely vivianite) and iron sulfide (likely greigite). These minerals commonly form at low temperatures in water-rich sediments on Earth and are often associated with microbial metabolisms that couple organic carbon oxidation to the reduction of iron and sulfate.
SHERLOC detected a G-band Raman feature interpreted as organic carbon, with the strongest signals at a location the team calls “Apollo Temple,” where vivianite and greigite co-occur. Texas A&M geobiologist Dr. Michael Tice, a lead author on the study published in Nature, said the spatial co-location of organics and redox-sensitive minerals is "very compelling," while cautioning that organic chemistry alone does not prove life.
Interpretations, caveats, and next steps
The research outlines two main scenarios: (1) abiotic geochemistry produced the observed mineral assemblages, or (2) microbial-like redox cycling influenced mineral formation in a cold, watery environment more than three billion years ago. Many abiotic sulfur-iron reactions require relatively high temperatures, but rover data show no evidence these rocks were heated to such conditions, increasing the plausibility of biologically mediated processes.
The team collected a core sample named "Sapphire Canyon" and sealed it for potential return to Earth. Laboratory analysis with high-sensitivity instruments could test isotopic patterns, fine-scale mineralogy and search for microfossils, providing stronger discrimination between biological and nonbiological origins.
Conclusion
While not definitive proof of past life, the Bright Angel findings meet NASA criteria for "potential biosignatures" and prioritize the site for sample-return consideration. Returning these samples to Earth remains the most direct path to resolving whether Mars hosted microbial ecosystems that exploited iron and sulfur chemistry similar to early Earth.
Source: scitechdaily
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