Engineers have discovered why multimillion-dollar space rovers like the Mars rover Spirit often get stuck in soft sand or gravel, and their solution could save future missions from similar crises.
Using computer simulations, University of Wisconsin–Madison mechanical engineers found that a flaw in how rovers are tested on Earth leads to overly optimistic conclusions about their behavior on extraterrestrial missions. The mistake occurs when researchers account for the moon’s weaker gravity but neglect the pull of Earth’s gravity on sand.
This oversight results from using a standard testing approach that assumes the moon’s surface is “fluffy” and shifts easily, making it harder for rovers to gain traction. In reality, the effects of Earth’s gravity on sand are more significant than previously thought, reducing the likelihood of shifting under a vehicle’s wheels.
The team developed an open-source physics simulation engine called Project Chrono, which allows researchers to model complex mechanical systems and accurately predict rover mobility on various surfaces. By using Chrono simulations, they found discrepancies between Earth-based test results and their simulations of the rover’s mobility on the moon.
This research has far-reaching benefits beyond NASA and space travel. The software is used by hundreds of organizations to better understand complex mechanical systems on Earth, from precision watches to military vehicles operating in off-road conditions.
The discovery highlights the importance of physics-based simulation in analyzing rover mobility and underscores the value of open-source software like Chrono. As Negrut notes, “Our findings underscore the value of using physics-based simulation to analyze rover mobility on granular soil.”
Source: https://techxplore.com/news/2025-07-robotic-space-rovers-stuck-figured.html