NASA’s Perseverance rover has picked up a rocky hitchhiker on Mars.
The rover has collected a “pet rock” tucked inside its left front wheel that has been riding along with Perseverance since early February. So far, its ridden across 5.3 miles (8.5 kilometers) with the Perseverance rover as it drives across its Jezero Crater home on Mars.
“This rock isn’t doing any damage to the wheel, but throughout its (no doubt bumpy!) journey, it has clung on and made periodic appearances in our left Hazcam images,” Eleni Ravanis, a student collaborator on NASA’s Perseverance mission from the University of Hawaii at Mānoa, wrote in an update (opens in new tab)†
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According to Ravanis, Perseverance picked up the small Mars rock on Feb. 4, the rover’s 341st day (or Sol as Mars days are called) on the Red Planet. At the time, Perseverance was exploring a rock formation called “Máaz” that scientists think was made up of ancient lava flows.
Since then, Perseverance has carried the rock north across its landing site, named for the famed late science fiction author Octavia E. Butler, and then west across the remains a region called “Kodiak,” the remains of a former delta at Jezero. The rover is currently in the midst of what NASA calls its Delta Front Campaign and may have drilled into its first sedimentary Mars rock, Ravanis wrote.
“Perseverance’s pet rock is now a long way from home,” Ravanis wrote. “It’s possible that the rock may fall out at some point along our future ascent of the crater rim. If it does so, it will land amongst rocks that we expect to be very different from itself.”
If that happens, a future Martian geologist might be a bit confused to find the rock so out of place, Ravanis added.
Hitchhiking rocks are no strangers to NASA’s Mars rovers.
In 2004, the Spirit rover picked up what Ravanis described as a “potato-sized” rock in its right rear wheel that eventually had to be dislodged. Perseverance’s cousin, the older Curiosity rover that will celebrate its 10th year on Mars in August, has also picked up rocks in its own battered wheels every now and again as it continues its own mission in Mars’ Gale Crater.
“While it’s unclear exactly how long these rocks stuck around, they tended to hop off after a few weeks,” Ravanis wrote. “Perseverance’s current companion is therefore on its way to setting Mars hitch-hiking records!”