Eleven years ago this week (or very nearly), the Spirit rover was noodling around in Gusev Crater on Mars when it drove over a thin hard crust of soil and broke through into a layer of soft sand underneath. The rover was already a little bit hobbled (understandable, since Spirit was something like 2,000 days into what was originally planned as a 90-day mission), and after months of trying, it became clear that Spirit wasn’t likely to move again. Unable to reach a position where its solar panels could be tilted toward the sun, Spirit froze to death during the Martian winter.
Larger rovers like Curiosity don’t have to worry about solar power, but getting stuck in soft surfaces is still a concern, since the options for getting a rover unstuck are limited—all you’ve really got to work with is the rover’s own mobility system.
In a paper published today in Science Robotics, researchers from Georgia Tech’s CRAB Lab led by Professor Daniel Goldman describe how they’ve worked with a NASA rover design to enable new mobility behaviors with actuated wheels that can avoid getting stuck. How do the wheels do that? By wiggling.