Perseverance Has Been Carrying a Rock in its Wheel for Over 100 Days

Why does a Mars rover have a rock in one of its wheels? Maybe it’s because a rover doesn’t have pockets.

Who among us hasn’t picked up a great rock, carried it around, maybe saved it for a long time, or even placed it somewhere safe or special? The Perseverance rover is doing just that, having carried a random Mars rock in its wheel for quite some time.

Back in early February, 2022 on Earth, about sol 341 for the lifetime of Perseverance on Mars, a rock ended up in the rover’s left front wheel. The rock has now been riding around with the rover for over 100 sols. NASA says the rock isn’t doing any damage, and the rover team estimates the rock has now traveled more than 8.5 kilometers (5.3 miles) from its original location.

Planetary scientist Paul Byrne did come up with a potential down-side to the rock in the wheel:

A quick reminder that, for some time now, @NASAPersevere has had a rock stuck in its front left wheel.

The rock doesn't seem to pose any problems.

But take a moment to think about the awful grinding noise that thing makes as it slides around every time the rover moves. pic.twitter.com/oqaxx1U66c

— Paul Byrne (@ThePlanetaryGuy) June 5, 2022

Maybe the microphone on Perseverance can capture some of that annoying grinding, clanking sound?

As Eleni Ravanis, a student collaborator with the Perseverance mission from University of Hawai?i at M?no, writes in a NASA blog post, this is not the first time a rock has hitched a ride on a Mars rover mission. Over 18 years ago, the Spirit rover picked up a “potato-sized” rock in its right rear wheel, and throughout the Curiosity rover mission, various rocks have gotten lodged or found its way inside the wheels.

“While it’s unclear exactly how long these rocks stuck around,” wrote Ravanis, “they tended to hop off after a few weeks. Perseverance’s current companion is therefore on its way to setting Mars hitch-hiking records!”

Maybe pet rocks are a popular fad on Mars.

The rock shows up in various images taken by the rover, especially in pictures taken by the Left Hazard Avoidance Camera. Scientists and engineers for the mission are definitely keeping an eye on the rock, hoping to see where and when the rock might fall out.

“If it does so, it will land amongst rocks that we expect to be very different from itself,” Ravaini said. “As one of our team members quipped this week, “we might confuse a future Mars geologist who finds it out of place!”

Lead image caption: NASA’s Mars Perseverance rover acquired this image of a rock inside the rover’s wheel, along with the area in front of it using its onboard Front Left Hazard Avoidance Camera A. This image was acquired on May 26, 2022 (Sol 449) at the local mean solar time of 15:39:48. Image Credit: NASA/JPL-Caltech