Thanks to missions that have been exploring the Red Planet since the 1970s, it has been established that Mars was once a much different place than what we see there today. Instead of an extremely cold, extremely dry, and irradiated planet with a very thin atmosphere, Mars once has a warmer, denser atmosphere and flowing water on its surface. Between 4.2 and 3.7 billion years ago, the planet began to undergo a transition whereby its atmosphere was slowly tripped by solar wind, causing its water to escape into space, collect in the polar ice caps, and retreat underground.
In other words, the planet went from having a habitable environment to one that is inherently hostile to life as we know it. The lingering question for scientists is how Mars made this transition – was it all at once, or in stages? According to new research from Rice University, NASA’s Perseverance rover has uncovered strong evidence in the Jezero crater that Mars experienced multiple periods where liquid water and habitable conditions existed in the region. These findings provide important clues for astrobiologists who are searching for evidence of past life on Earth’s “Sister Planet.”
The study was led by PhD candidate Eleanor Moreland at Rice University’s Department of Earth, Environmental, and Planetary Science. She and her Rice colleagues – including Dr. Kirsten Siebach, her PhD advisor – were joined by researchers from Texas A&M University, Stony Brook University, University of Nevada Las Vegas, the Université Claude Bernard Lyon, the Lunar and Planetary Institute (LPI), the NASA Johnson Space Center, and NASA Jet Propulsion Laboratory (JPL). Their findings were published in the Journal of Geophysical Research: Planets.
This conclusion was reached after Moreland and her team analyzed data from Perseverance’s Planetary Instrument for X-ray Lithochemistry (PIXL). This instrument studies the chemical composition of Martian rocks by bombarding them with X-rays and, in the process, offers the most detailed geochemical measurements ever collected by an interplanetary mission. Their analysis also relied on the Mineral Identification by Stoichiometry (MIST) algorithm, a computational tool developed by researchers at Rice to recognize minerals in high-resolution geochemical data.
In the process, the team identified twenty four types of mineral that revealed the dynamic history of volcanic rocks in the Jezero Crater that were altered during interactions with liquid water on Mars. As the building blocks of rocks, minerals form under specific environmental conditions like temperature, pH, and the chemical makeup of fluids, making them a reliable record of planetary history. Their study provides a thorough compilation of minerals identified during the first three years of the Perservance mission. As Moreland explained in a Rice University press release:
The minerals we find in Jezero using MIST support multiple, temporally distinct episodes of fluid alteration, which indicates there were several times in Mars’ history when these particular volcanic rocks interacted with liquid water and therefore more than one time when this location hosted environments potentially suitable for life. These minerals tell us that Jezero experienced a shift from harsher, hot, acidic fluids to more neutral and alkaline ones over time — conditions we think of as increasingly supportive of life.
For water-based erosion, water chemically weathers rocks and creates salts or clay minerals, and the specific nature of these depends on the environmental conditions. The 24 identified minerals in Jezero revealed a dynamical history and point to three types of fluid interactions, each of which have different implications for habitability. The first suite of minerals (greenalite, hisingerite, and ferroaluminoceladonite) indicate the rocks on the crater floor (some of the oldest in the study) was once covered by high-temperature acidic fluids. This would have been the least habitable episode for life, though extreme environments on Earth show that it would not be impossible.
Mars Perseverance rover – PIXL studies a rock (artist concept). Credit: NASA/JPL-Caltech
The second suite included minerals like minnosotaite and clinoptilolite, which form at lower temperatures, found in the crater floor and upper fan region. These minerals indicate a period where moderate, neutral fluids that support more favorable conditions for life covered a larger area. The third suite indicated the highest level of potential habitability and included sepiolite, a mineral that forms under moderate temperatures and alkaline conditions. This mineral was widely distributed across all the locations visited by the rover, revealing an episode where liquid water covered the entire area and deposited sediment in the crater.
While this study does not present evidence of potential biosignatures, it does show that conditions favorable to habitability once existed in Jezero. Combined with the recent sample obtained in Sapphire Canyon, this evidence provides further insight into Mars’ warmer, wetter past and a period of potential habitability. “MIST not only informs Mars 2020 science and decision-making, but it is also creating a mineralogical archive of Jezero Crater that will be invaluable if samples are returned to Earth,” said Moreland. Every new mineral discovery also brings scientists closer to identifying which samples should be returned.
This research was supported by Mars 2020 Participating Scientist grants, JPL, the Mars 2020 PIXL team, the Mars 2020 Returned Sample Science Participating Scientist program and NASA’s Mars Exploration Program.
Further Reading: [Rice University](https://news.rice.edu/news/2025/new-mars-research-reveals-multiple-episodes-habitability-jezero-crater, JGR Planets