Purdue study shows Perseverance detected ancient hot water on Mars
NASA’s Perseverance rover uncovered evidence that igneous rocks along the inner edge of Jezero crater on Mars underwent at least three separate episodes of water alteration, including the circulation of heated subsurface fluids. Researchers led by Purdue University identified the chemical markers across an unexpected volcanic formation known as the Margin Unit, according to findings published in the journal Communications Earth & Environment on Monday, September 21, 2026.
“Before we arrived at the Margin Unit, the main hypothesis derived from orbital observations was that the carbonate seen from orbit formed from interaction with the lake that existed in Jezero Crater,” said Candice C. Bedford, research scientist in the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University and lead author of the study. “But now we know that this location became a sort of crossroads for aqueous systems. The Margin Unit findings are important because Jezero Crater sits inside one of the largest exposures of carbonate on Mars, so what we learn here reaches well beyond this crater.”
Laser analysis of volcanic rocks along the crater rim
The research team analyzed more than 185 bedrock targets across the Margin Unit using the SuperCam instrument mounted on the mast of Perseverance. The instrument fires laser pulses capable of vaporizing rock fragments from a distance of up to 6.5 meters (21 feet) to determine the chemical composition of the resulting plasma, alongside examining reflected light. The rover investigated these targets across an elevation gradient of 265 meters (about 870 feet) as it climbed along the rim of the 45-kilometer (28-mile) wide crater.
Initial orbital data led planetary scientists to expect sedimentary layers deposited along the shoreline of the ancient body of water that once filled Jezero crater. Instead, the ground-level data gathered since the rover reached the inner rim on Friday, September 1, 2023, revealed olivine-rich igneous rocks that originated from cooled molten material. These volcanic baserocks preserved detailed evidence of repeated interactions with surface and subsurface water over extended geological periods.
Three separate phases of aqueous alteration
Chemical analyses revealed that the igneous bedrock underwent a sequence of three distinct chronological stages of fluid exposure, each producing different mineral products within the rock fractures:
- Stage one: Ground water saturated with carbon dioxide reacted directly with olivine, precipitating distinctive ridges of carbonate minerals throughout the fractured bedrock.
- Stage two: Exposure to lake water or fluctuating groundwater tables remobilized earlier minerals and led to the concentrated deposition of silica, especially below ancient lake waterlines.
- Stage three: Deeply heated hydrothermal water circulated through the rock formation, depositing mineral veins containing calcium sulfate and fluorite in the eastern Margin Unit.
Perseverance in the Wild Martian West 🤠
— NASA (@NASA) May 12, 2026
Our Perseverance Mars rover snapped some photos beyond the western rim of Jezero Crater—the farthest west the rover has ever gone on the Red Planet. See what we found there: https://t.co/nIkwxstE26 pic.twitter.com/6gJ9xgnVy5
Reactions that mirror early terrestrial habitability
The discovery of hydrothermal activity holds significance for planetary habitability because similar systems on early Earth sustained microbial life through serpentinization reactions, in which water interacting with olivine produces molecular hydrogen. In these subterranean environments, heated fluids provide chemical energy sources that can sustain living systems independent of solar radiation. The carbonate deposits in Jezero crater represent one of the most extensive exposures on the Martian surface, offering a window into how volcanic crust interacted with changing climates across the planet.
“If there is one thing I have learned after 10 years working with Mars rovers, it is that Mars constantly throws surprises at you,” Bedford said. “It is very rare that things are as we expect them to be from orbital data. They are usually far more complex and interesting, which is what makes planetary exploration so exciting.”
Geologists have not yet determined the absolute chronological ages or exact timeframes for each of the three aqueous events, having established only their relative order. The Perseverance rover continues to collect and seal selected rock cores inside protective tubes on Mars, setting aside physical samples intended for eventual laboratory analysis on Earth under future phases of the Mars Sample Return program.
