It takes a lot to astonish a Mars rover team that has seen everything from an ancient beach to a rock that might hint at long-ago life. NASA’s Perseverance rover found an unusual rock on the rim of the Jezero crater. The odd, bubbly-looking formation stood out from its surroundings. “Last week the Perseverance Science Team were astonished by a strange rock comprised of hundreds of millimeter-sized spheres,” said Alex Jones, a doctoral researcher at Imperial College London, in a rover update on March 21.
Perseverance has been poking around a spot named Broom Point at the lower slopes of an area called Witch Hazel Hill. The rover originally landed in the Jezero crater in early 2021. It completed an epic climb up the crater rim last year and is exploring a new part of Mars. This is where the rock with “shocking spherules” was found.
Spherules In Mars Rock
The team named the rock St. Pauls Bay. Images of the rock show some peculiar shapes among the spherules. Some are angular. Some are elliptical. Others have small pin-sized holes. “What quirk of geology could produce these strange shapes?” Jones asked.
Perseverance looked at the rock from afar, but also got a close view using its SuperCam Remote Micro Imager instrument on March 11. The detailed view highlights the variety of spherule shapes.
Jones shared a couple of ways that a rock like this might form. The spherules could be concretions created through a process where water interacts with pores in a rock. That’s not the only possible explanation for the spherules. “They also form on Earth by rapid cooling of molten rock droplets formed in a volcanic eruption, for instance, or by the condensation of rock vaporized by a meteorite impact,” Jones said.
The science team is working on teasing out the rock’s origin. What’s obvious is that it’s not in its original place. Orbital images of the Witch Hazel Hill area show bands of light and dark rock. The St. Pauls Bay rock may be associated with one of the darker bands, but more study is needed.
Perseverance’s continued explorations might turn up similar rocks. “Placing these features in geologic context will be critical for understanding their origin, and determining their significance for the geological history of the Jezero crater rim and beyond,” Jones said.
Odd Rocks On Mars
Mars has a history of revealing surprising geologic finds to NASA’s rovers. The Opportunity rover famously spotted a group of spherical formations in 2004. These round rocks became known as Martian “blueberries.” More recently, the Curiosity rover drove over and broke apart a rock to reveal yellow sulfur crystals in mid-2024.
Perseverance and Curiosity are NASA’s currently operating rovers on the red planet. They have a lot on their science plates, but one of their main goals is investigating whether or not Mars might have once been home to microbial life long ago. It’s a tough question to answer from a distance, so Perseverance is also collecting rock samples in the hope we’ll be able to return them to Earth one day for closer study.
St. Pauls Bay will remain a bit of a mystery for now. Add it to the list of weird and wonderful Mars rover finds that will keep scientists busy for years.
