Landing on another celestial body is incredibly challenging. Despite many successful missions, space agencies still face failures when trying to land spacecraft. For instance, NASA’s Spirit rover on Mars got stuck in soft sand due to unexpected surface conditions.
Recent research indicates that we might not fully understand the physics of these different planetary surfaces. When preparing missions, agencies often replicate Earth environments, such as deserts or specialized terrains.
Bryan Martin, a flight software manager at NASA’s Jet Propulsion Laboratory (JPL), pointed out that they consider factors like the size and shape of rocks in their tests. They believe their extensive ground testing gives them confidence for rover navigation on other planets.
However, scientists have noticed that merely reducing a rover’s weight to simulate lower gravity on Mars can lead to overly optimistic results. For example, when testing the Curiosity rover, its mass was reduced from 907 kg (2,000 lbs) to 340 kg (750 lbs), a weight equal to what it would be on Mars. Yet, the soil in places like California’s Mojave Desert responds differently under Earth’s gravity compared to Mars.
NASA and the China National Space Administration have concentrated on how low gravity affects rovers but may have overlooked how it impacts the terrain. While developing the now-canceled VIPER mission, researchers used a physics simulator which revealed a significant gap between test conditions on Earth and lunar soil behavior.
Dan Negrut, a mechanical engineering professor at UW-Madison, emphasized the importance of examining how gravity affects both the rover and the surface. The research highlights the need for physics-based simulations to enhance rover mobility on various terrains.
Interestingly, the study indicates that testing a single wheel may yield more reliable data than testing the entire rover. The team advocates for robust terramechanics models to guide future rover designs.
This insight could change how space agencies prepare for their missions, ensuring they account for both rover dynamics and surface behavior to avoid mishaps. The findings were published in the Journal of Field Robotics, emphasizing the critical role of advanced simulations in future planetary exploration.
For more details on this research, check the Journal of Field Robotics here.
