My colleague noticed something odd in the latest batch of photos from NASA’s Perseverance Mars rover: a rounded boulder appears to be carefully balanced atop a jagged outcrop. How did it get there?
The photo was taken in the Jezero crater of Mars by Perseverance’s right Mastcam Z on Sol 466, which corresponds to June 12 here on Earth.
I emailed NASA asking what the rock could be and if there was anything really strange here. James Rice, a geologist with the Mastcam-Z team at Arizona State University’s School of Earth and Space Exploration, replied:
Balance rocks (sometimes referred to as Precariously Balanced Rock PBRs) of various sizes, ranging from small rock sizes (inches) to formations hundreds of feet high, occur naturally and are not really unusual. Often a balancing rock is actually connected to the larger underlying rock by a rod or pedestal. The Martian balance rock pictured is on the Rockytop outcrop near the base of the delta and was most likely formed after significant wind (wind) and/or chemical erosion pulled it out of the local bedrock.
These types of features are more than just geological curiosities; in fact, they have been called “inverse seismometers” because the existence of PBRs makes it possible to measure earthquakes/mars that did not occur. If these rocks are still balanced, the ground hasn’t moved enough to knock them over. We can therefore use these characteristics to learn more about the seismic history of a region.
Ah yes, a classic PBR. Glad that’s cleared up!
Around the same time as this image, the Perseverance rover got a photo of a shiny piece of material nestled in some rocks, which NASA thinks could be a piece of the rover’s thermal blanket since landing in 2021. NASA tweeted that the rover landed 2 kilometers (1.25 miles) from where the rest of the cover was found, but notes that it could have been blown around or landed there on its own.
We have strange pictures of Mars all the way, and we saw rocks that look like squirrels, spoons, doors, and more. Our eyes play tricks on us, and that’s especially true when looking at an alien landscape filled with familiar and unfamiliar sights. We see two-dimensional representations of a three-dimensional world, so these optical illusions are inevitable.