NASA's Mars rover has made groundbreaking discoveries in Jezero Crater, revealing that the Red Planet experienced multiple episodes of flowing water that could have created conditions suitable for life. Scientists have identified over two dozen types of minerals that illustrate a dynamic history of volcanic rocks altered by interactions with liquid water in this ancient Martian region.
The findings indicate that Jezero Crater hosted habitable environments on several occasions throughout Mars' history. The water present in the crater chemically transformed volcanic rocks into salts and clay minerals, revealing three distinct episodes of fluid activity. The first episode involved localized high-temperature acidic water, which was harsh and least favorable for life. In contrast, the second episode formed under moderate, neutral conditions, leading to more hospitable environments over a broader area.
The third episode created widely distributed, low-temperature alkaline conditions that are considered highly suitable for life. Eleanor Moreland, a graduate student from Rice University who led the study, stated, "The minerals we find in Jezero support multiple, temporally distinct episodes of fluid alteration. This indicates there were several times in Mars' history when these particular volcanic rocks interacted with liquid water, thus allowing for potential life-supporting environments."
Since its landing in February 2021, NASA's Perseverance rover has been exploring the 28-mile-wide Jezero Crater in search of signs of ancient life. Evidence gathered by the rover confirms that this crater was once home to an ancient lake and river delta. Notable discoveries include unusual rock formations and organic molecules, further supporting the idea that conditions suitable for life may have existed multiple times throughout Mars' history.
To analyze the rover's data effectively, the research team utilized the Mineral Identification by Stoichiometry (MIST) algorithm along with the Planetary Instrument for X-ray Lithochemistry (PIXL). This innovative tool identifies minerals in chemical data by comparing measurements to a comprehensive database of known minerals. The first group of minerals discovered includes greenalite, hisingerite, and ferroaluminoceladonite, which formed in hot, acidic water confined to the crater floor.
Greenalite is an iron-rich mineral that typically forms in high-temperature, low-pH environments. Hisingerite is a clay-like mineral resulting from the reaction of volcanic rocks with acidic water, while ferroaluminoceladonite develops in volcanic rocks exposed to hot, acidic fluids. These rocks are among the oldest analyzed in the study, and their formation under extreme conditions made them least favorable for life, as high temperatures and acidity can damage biological structures.
The second group of minerals identified formed in moderate, near-neutral water, creating more favorable conditions for potential life and covering a larger area of the crater. Notable minerals in this group include minnesotaite, a clay-like mineral found on both the crater floor and the upper fan region, and clinoptilolite, a zeolite mineral that appeared exclusively on the crater floor.
The third group of minerals, which formed under low-temperature, alkaline conditions, is regarded as highly habitable from an Earth perspective. Sepiolite, a common alteration mineral on Earth, formed under moderate temperatures and alkaline conditions and was widely distributed across all explored areas. Its presence indicates a widespread episode of liquid water that created habitable conditions and filled sediments across Jezero Crater.
Due to the challenges of preparing and scanning Mars samples with the same precision as Earth rocks, the research team developed a model to account for uncertainties and enhance their findings. Using a statistical approach, MIST repeatedly tested mineral identifications while considering potential errors, similar to how meteorologists predict hurricane paths through multiple simulations. Moreland emphasized, "Our error analysis allows us to assign confidence levels to every mineral match. MIST not only informs Mars 2020 science and decision-making but is also creating a mineralogical archive of Jezero Crater that will be invaluable if samples are returned to Earth."
The findings from NASA's Perseverance rover confirm that Jezero Crater, once the site of an ancient lake, has a complex and dynamic history of water activity. The evidence of multiple episodes of water flow strengthens the case for the potential habitability of Mars, showcasing a rich geological history that could have supported life.
