Perseverance data documents the multiple impact history at Jezero Crater
Figure 8 from the paper.
Using data obtained last year when the Mars rover Perseverance did its first exploration outside of Jezero Crater, scientists now believe that material documents not only the impact that formed Jezero, but the much larger Isidis Basin impact eons earlier.
You can read their paper here. The image to the right is the paper’s Figure 8, showing the many impact spherules found at the site, dubbed Broom Point. From the press release:
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.
In reviewing the data, the scientist found evidence of two major impacts.
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.
This conclusion is not surprising. Orbital data has clearly suggested this sequence of events for decades. Scientists now have confirmed it geologically with actual ground samples.
In addition, the data suggested the occurrence in the past of fast debris flows, likely caused “when molten rock hits water or ice that instantly flashes into steam.” Though Jezero Crater is now in the dry equatorial regions of Mars, the geological evidence has consistently suggested there was once ice or water there. This data reinforces that conclusion.
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