NASA's Perseverance took this selfie at "Witch Hazel Hill" on Jezero Crater's rim on May 10, 2025. The small dark hole in the rock in front of the rover is the borehole made when the rover collected the "Bell Island" sample. The small puff of dust left of center and below the horizon line is a dust devil. Credit: NASA/JPL-Caltech/MSSS
Reading between layers
After descending the western rim of Jezero Crater in early 2025, Perseverance began examining Broom Point with its science instruments. Their data revealed six distinct rock types, including breccias - rocks built from angular fragments - alternating with layers of fine-grained, pulverized rock dust. Rock fragments within the breccias are pocked with gas-bubble cavities, indicating they were once molten.
The presence of tiny, dark, glassy beads within the layers offered an important clue about how these rocks formed. While volcanoes can produce similar glassy droplets, they rarely occur in such high abundance, pointing to asteroid impacts, instead, as the primary architect. In fact, the largest beads rival those flung out by the dinosaur-killing Chicxulub asteroid's impact on Earth.
NASA's Perseverance rover captured its own tracks descending from the rim of Jezero Crater. The bright-colored rocks running from middle left to middle right of the image, a formation dubbed the "Broom Point member," are likely more than 3.9 billion years old, making them among the oldest terrain ever examined by a Mars rover. Credit: NASA/JPL-Caltech/ASU/MSSS
Because these distinct rock types repeat multiple times throughout this thick sequence of rock, it indicates that high-energy impact events happened again and again across this region of early Mars.
"The different rock layers are a record of variable-sized impacts occurring at different distances from where this rock sequence was accumulating," said Alex Jones, a Ph.D. student in planetary geology at Imperial College London and lead author of the paper. "Some large impacts took place very far away, some small impacts nearby. Their debris all ended up landing here, constructing this thick section of rock."
How these layers formed may suggest an interaction with water or ice. Several of the layers look like they may have been formed by fast, ground-hugging debris flows. On Earth, these powerful, fluid-like surges can occur when molten rock hits water or ice that instantly flashes into steam.
Cosmic one-two punch
Some of Broom Point's layers tilt at angles exceeding 80 degrees - nearly vertical - which is far too steep to be caused by the impact that created Jezero Crater.
Instead, scientists suspect a cosmic "one-two punch" shaped this landscape long ago. First, a colossal asteroid impact created the 1,200-mile-wide (1,900-kilometer-wide) Isidis Basin, one of the largest impact basins on Mars, upending and tilting the once-flat rock layers. Later, a second asteroid likely struck, forming Jezero Crater, which measures 28 miles (45 kilometers) across. This second impact fractured and uplifted the already-tilted rocks into the dramatic formations the rover sees today.
To pin down exactly when these events took place, the Perseverance team collected two core samples, dubbed "Bell Island" and "Main River." If a future mission were to return them to Earth, laboratory dating could determine when and how often impacts were striking early Mars - and, by extension, the infant Earth, whose own early impact record has been erased by billions of years of plate tectonics.
"During this violent era, it wasn't rain or snow falling from the sky, but an almost constant barrage of molten rock droplets and pulverized dust kicked up by asteroid impacts," said Jones. "If we can pin down the ages of these layers, it would be like reading a cosmic weather report from 4 billion years ago."
This orbital map shows the path NASA's Perseverance Mars rover took from its 2021 landing site in Jezero Crater to the "Broom Point" location in mid-2025. Credit: NASA/JPL-Caltech/MRO/HIRISE/UA/ICL
Notes for journalists:
This study is published in Journal of Geophysical Research: Planets, an AGU journal. View and download a PDF of the study here. Neither this press release nor the study is under embargo.
Paper title:
"Stratigraphy Preserved on the Jezero Crater Rim Reveals Repeated Impacts on Early Mars"
Authors:
- Alexander J. Jones, Department of Earth Science & Engineering, Imperial College London, London, UK
- Sanjeev Gupta, Department of Earth Science & Engineering, Imperial College London, London, UK
- Robert Barnes, Department of Earth Science & Engineering, Imperial College London, London, UK
- Samantha Gwizd, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Kathryn M. Stack, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Briony Horgan, Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA
- Sanna Alwmark, Department of Earth and Environmental Sciences, Lund University, Lund, Sweden
- Athanasios Klidaras, Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA
- Eleni Ravanis, University of Hawaiʻi at Mānoa, Hawaiʻi, USA
- Sarah Fagents, University of Hawaiʻi at Mānoa, Hawaiʻi, USA
- Gerhard Paar, Joanneum Research Institute for Digital Technologies, Graz, Austria
- James F. Bell III, School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
- Justin N. Maki, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Margaret Deahn, Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA
- Candice Bedford, Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA
- Nicolas Mangold, Laboratoire Planétologie et Géosciences, CNRS UMR6112, Nantes Université, Univ Angers, Nantes, France
- Michael Bramble, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Justin I. Simon, Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, Texas, USA
- Lisa Mayhew, Department of Geological Sciences, University of Colorado Boulder, Colorado, USA
- Cathy Quantin-Nataf, Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, Université de Lyon, Université Claude Bernard Lyon, Ecole Normale Supérieure de Lyon, Université Jean Monnet Saint Etienne, CNRS, Villeurbanne, France
- Larry Crumpler, New Mexico Museum of Natural History & Science, Albuquerque, New Mexico, USA
- Christoph Traxler, VRVis GmbH, Vienna, Austria
- Chris Herd, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada
- Olivier Beyssac, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, Muséum National d'Histoire Naturelle, Paris, France
- Nicolas Randazzo, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada
- Uni Árting, Jarðfrøðingur, Faroese Geological Survey, Faroe Islands
- Roger C. Wiens, VRVis GmbH, Vienna, Austria
- Kenneth A. Farley, Division of Geological and Planteary Sciences, Caltech, Pasadena, California, USA
