Perseverance, NASA’s jeep robot on the surface of Mars, has an unusual travel companion: a rock. They met about four months ago, and have traveled 8.5 kilometers together.
It’s a real thorn in the side, which has been stuck on the robot’s left front wheel since early February. You can see it periodically in the logs of the Hazcam front camera — used for navigation and collision avoidance.
Analyzing the images, the researchers believe the small rock settled on day 4/2, as Perseverance explored the geological formation called Máaz, created by past lava flows.
He has since hitched a ride to the mission’s landing site, named Octavia E. Butler, and to the Kodiak region, a remnant of an ancient river delta in Jezero Crater. If life ever existed on the red planet, even if just microbial activity billions of years ago, this is the region most likely to hold evidence.
“Perseverance’s pet rock is now a long way from home,” wrote Eleni Ravanis, a student at the University of Hawaii at M’noa and a NASA contributor. “It is possible that it will break off at some point along the future ascent of the crater rim. If that happens, it will fall among rocks that we believe are very different from it.”
The inseparable friend is not causing any damage to the robot wheel or its functioning. In fact, it’s a common occurrence in terrain as rough as Mars. Perseverance himself had to deal with rock debris earlier in the year.
The older rovers, Spirit and Curiosity, also had their pet rocks, but we’ve never seen one stay that long.
“While it’s unclear exactly how long these rocks remained, they tended to pop out after a few weeks,” Ravanis said. “Perseverance’s current companion is therefore on track to set hitchhiking records on Mars.”