This story is part of Welcome to Mars, our series exploring the red planet.
It’s hard for me to pick a favorite rock on Mars. There’s the “butt crack” and the “flower” and, of course, the stunning blueberries, but my current geologic darling is the NASA Perseverance rover wheel rock, a chunky stowaway that has been clinging to the inside of the vehicle’s shoe since at least early February.
The wheel rock has now been upgraded to “pet rock” status by Eleni Ravanis, a Perseverance student collaborator from the University of Hawaiʻi at Mānoa. “If this pet rock could talk, it might tell us about the changes it’s noticed as we travelled 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,” Ravanis wrote in a mission update on Thursday.
The rock is located in the rover’s left front wheel and has so far hitchhiked over 5.3 miles (8.5 kilometers) across the landscape. It’s like the Marco Polo of Martian rocks.
The rock first came to my attention in early March. At that time, NASA spokesperson Andrew Good said the rock was “not perceived as a risk.” That status hasn’t changed. Perseverance is equipped with tough aluminum wheels featuring an upgraded design compared to its older sibling, the Curiosity rover. Curiosity’s wheels have taken quite a beating in its many years on Mars.
The rock could stick around, or it might fall out as Perseverance continues to explore the Jezero Crater, collecting rock samples and looking for signs of ancient microbial life. If it does fall out, it will be far from home and among geologic strangers. Ravanis had a message for any future Martian geologist who might be mapping the crater: “If you’ve found a rock that looks out of place, you might just be looking at the former pet rock of Perseverance!”
