Humanity has its sights set on visiting Mars in person someday. Future explorers might want to pack some lime juice, cilantro and tomatoes to go along with a delightful avocado-shaped rock spotted by NASA’s Perseverance rover in the Jezero Crater.
The rock isn’t actually a fruit, but it was a fascinating target for the rover’s cameras thanks to its eye-catching shape. The rock has an oval appearance with a scooped-out center and a round lump sticking up in the middle, much like an avocado pit sitting inside an empty skin. It’s fun to look at it, but it also tells a story about the forces that shape rocks on windy and dusty Mars.
Perseverance snapped the rock on September 8 with a mast-mounted camera called Mastcam-Z. The camera is equipped with a powerful zoom lens to get close up views of distant objects.
I have a query in to NASA’s rover team to learn more about the rock, but the Seti Institute, a not-for-profit research group engaged in the search for life in the universe, posted a likely explanation for the rock’s shape to X on Thursday.
The Seti Institute estimated the rock is up to 8 inches long. “What a nice example of differential erosion in this split Martian rock at Jezero crater. Now, that’s sedimentology and erosion in action,” the institute tweeted, jokingly calling it “a fossilized Martian giant avocado.” Differential erosion happens when rocks erode at different rates. In the case of the Martian avocado, that means the round piece inside the bowl is more resistant to erosion than the surrounding rock.
Perseverance has been investigating an ancient riverbed in the Jezero Crater. Mars might be dry and dusty now, but it was once a more watery place. A wider view from the same day shows a landscape littered with rocks and sand. There are plenty more fancifully shaped rocks to see.
Mars is a pareidolia paradise. Pareidolia is the human phenomenon of seeing familiar objects in random shapes. Perseverance snapped two other fun rocks in August that looked like a shark fin and a crab claw. While these rocks are reminiscent of Earth objects, that’s all they are. Scientists have yet to find life on Mars, though the search is on for evidence of ancient microbial life on the red planet.
The Perseverance rover is constantly sending back postcards from Mars in the form of raw images as it cruises through the Jezero crater. The rover is a sophisticated rolling laboratory. One of its key missions is to help us understand if Mars ever hosted microbial life. To that end, it’s collecting rock samples that NASA hopes to fetch with its future Mars Sample Return mission. Scientists need to have Percy’s rocks in labs on Earth to fully determine what they’re telling us about the possibility of past life on the planet.
The avocado rock is one small piece of Mars’ story. It tells a tale of erosion and resistant rocks and how fantastical shapes can form in the Martian environment. But if there’s ever to be guacamole on Mars, we’re going to need future astronauts to take it there.