- Perseverance rover found a 245-foot-thick rock layer on Jezero Crater's rim on Mars
- The Broom Point member rock sequence is over 3.9 billion years old and very ancient
- Rocks show evidence of multiple asteroid impacts shaping Mars' early surface
NASA's Perseverance Mars rover has uncovered new evidence about the ancient history of Mars. The rover found a 245-foot-thick layer of old rock on the rim of Jezero Crater, showing that the formation was created by repeated asteroid impacts, reported NASA.
The rock sequence, called the "Broom Point member" by the rover's science team, is likely more than 3.9 billion years old. It is among the oldest terrain ever examined by a Mars rover.
The findings were released on Wednesday in the Journal of Geophysical Research: Planets and provide a look into one of the most violent periods in the history of the solar system.
Ken Farley, Perseverance deputy project scientist at Caltech in Pasadena, California, said that since leaving Jezero, Perseverance had been exploring a new frontier both geographically and geologically. He explained that this chapter of Martian time predates the crater itself.
Farley said that on Earth, the earliest geological history has been broken up, changed and erased by plate tectonics. He added that because Mars does not have plate tectonics to recycle its crust, the ancient record remains intact and gives scientists a rare view of a geological period that does not exist on Earth.
After climbing the western rim of Jezero Crater in late 2024, Perseverance began studying nearby locations using its science instruments. Data collected at Broom Point revealed six different rock types, including breccias, which are rocks made of angular fragments, along with layers of fine-grained, crushed rock dust.
Scientists found that rock fragments inside the breccias contained gas-bubble cavities, showing that they were once molten. The presence of tiny, dark, glassy beads in the layers also provided clues about how the rocks formed.
Researchers said that while volcanoes can create similar glassy droplets, they are rarely found in such large amounts. This pointed to asteroid impacts as the main cause of the rock formation. Some of the largest beads were similar in size to those produced by the Chicxulub asteroid impact that caused the extinction of dinosaurs on Earth.
The repeated appearance of different rock types throughout the thick rock sequence showed that powerful impact events happened multiple times across the region in early Mars.
Alex Jones, a PhD student in planetary geology at Imperial College London and lead author of the paper, said that the different rock layers recorded impacts of different sizes that happened at different distances from where the rocks formed. He explained that some large impacts occurred very far away, while smaller impacts happened nearby, and their debris eventually collected to create the thick rock section.
Scientists said the formation of these layers may also suggest an interaction with water or ice. Some layers appear to have formed through fast-moving debris flows, which on Earth can happen when molten rock comes into contact with water or ice that quickly turns into steam.
