- NASA's Perseverance rover has had a rock stuck on one of its wheels for the last four months.
- While other rocks have hitched weeks-long rides on rovers, this rock has been stuck for months.
- The Perseverance rover is scouring an ancient river delta searching for evidence of microbial life.
Since at least early February, NASA's Perseverance rover has had a rock clinging to its front left wheel. While other Martian rocks have previously latched onto rovers for weeks at a time, this particular rock has stuck around for months — reaching "pet rock" status.
After landing in Jezero Crater in February 2021, the Perseverance rover began sampling Martian rocks and looking for signs of ancient life. And since at least February 2022, the car-sized robot has not been doing it alone. A little pet rock hitched a ride on NASA's crater floor campaign and has since continued a long trek on the red planet.
"If this pet rock could talk, it might tell us about the changes it's noticed as we traveled back north through the Octavia E. Butler landing site, and then west, passing the spectacular remains of the former extent of the delta, 'Kodiak,' on our journey to the western Jezero delta," Eleni Ravanis, a Perseverance student collaborator from the University of Hawaiʻi at Mānoa, wrote in a mission update last week.
The agency says the rock is not damaging the wheel, but it shows up frequently in the rover's Hazcam — a camera used to detect obstacles in the rover's way. "We've seen these kinds of rocks get 'caught' in Curiosity's wheels from time to time, too," Andrew Good, a NASA spokesperson, told CNET in March. Roughly 18 years ago, a potato-sized rock found its way into the Spirit rover's rear right wheel.
"They occur during cross-slope drives, and tend to fall out entirely on their own after a while (there's no particular way to get this rock out of our 'shoe')," Good wrote in an email to CNET.
But while other rocks fall out on their own within weeks, Percy's new rock companion is sticking around. The rock has so far hitchhiked more than 5.3 miles across the Martian landscape, according to NASA.
Since astronomers are unsure when the rock will end its journey, Ravanis has a message for any future Martian geologists mapping Jezero Crater: "If you've found a rock that looks out of place, you might just be looking at the former pet rock of Perseverance!"