“It’s like a ski jump,” Ramsley said. “The boulders keep going but suddenly there’s no ground under them. They end up doing this suborbital flight over this zone.”

All told, Ramsley says, the models answer some key questions about how ejecta from Stickney could have been responsible for Phobos’ complicated groove patterns.

“We think this makes a pretty strong case that it was this rolling boulder model accounts for most if not all the grooves on Phobos,” Ramsley said.