It's the end of an era, at least for the Perseverance rover on Mars, who has lost a long-time friend.

For 427 sols or days on Mars, Perseverance has been carrying around a rock in one of its wheels. We've been following the saga of this pet rock, which for over a year has stuck with Perseverance over the hills and sands of the Martian landscape.

However, according to Dr. Gwénaël Caravaca, who works with the rover's SuperCam instrument, the team found out overnight in the latest Hazcam image that the rock has been lost.

"It spent 427 Sols with us (more than an Earth year!), and traveled about 10 km since Sol 341," Caravaca tweeted. "Farewell Rock Friend, you will be missed!"

The rock was first seen back in early February, 2022 (on Earth, or about sol 341 for the lifetime of Perseverance on Mars). It somehow ended up in the rover's left front wheel and like a good friend, stuck with the rover for a long time.

Someone said Perseverance put its favorite rock in its wheel because the rover doesn't have pockets. NASA has said the rock wasn't doing any damage, but I wonder if Perseverance found the clunking, grating noise annoying at times.

Rover engineers have said that rocks can get into the wheels when the rovers are traversing slopes. They can also get in there as the rover moves over loose terrain and as the rover's weight breaks rocks into pieces.

Image of NASA's Mars Perseverance rover's (empty) wheel.
NASA's Mars Perseverance rover acquired this image of its (empty) wheel using onboard Front Left Hazard Avoidance Camera A on April 18, 2023 (Sol 768). (NASA/JPL-Caltech)

During the year when the rover was carrying the rock, many humans could relate. 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?

But maybe Perseverance ditched this rock because it's looking for an even better one. And there appears to be a few rocks to choose from.

An image of a rock field on Mars also showing the Ingenuity Mars Helicopter in the bottom right corner.
This image of a rock field on Mars also shows the Ingenuity Mars Helicopter and was taken by the Mastcam-Z instrument of the Perseverance rover on June 15, 2021, the 114th Martian day, or sol, of the mission. (NASA/JPL-Caltech/ASU/MSSS)

You can find all the raw images from Perseverance – and see what it sees almost every day – at the rover's website.

This article was originally published by Universe Today. Read the original article.