Description: Single-wheel testbeds have been used to evaluate the tractive performance of locomotion and other rover mobility elements in soils simulating lunar regolith. Understanding Wheel-Regolith Interaction for Mobility under Lunar Gravity will develop a small-scale mobility testbed to assess the mobility performance of locomotion elements during parabolic flight tests that simulate lunar gravity. The project will test specific modes of characterization including physical slopes and drawbar pull force measurements. Data collected from these in-flight experiments is expected to characterize the effects of reduced gravity on the dynamic interaction of wheels and lunar soil simulants and improve current predictions on how scaled versions of such locomotion elements will behave on the Moon. Problem Statement The current practice for rover wheel testing is to directly scale the applied downforce to match the target environment (e.g., one-sixth of Earth’s gravity for lunar missions). This scaling does not account for the dynamic effects of a partial gravity field within the granular media. Prior research indicates that wheel testing that does not account for a partial gravity field within the granular media may overestimate mobility performance, which impacts how lunar rovers are currently designed and tested. Parabolic flight test results could help verify the proper scaling of wheel-terrain interaction and extrapolate from terrestrial mobility tests to expected lunar mobility performance. Tech Maturation Zero Gravity Corporation’s parabolic flight tests simulating lunar gravity will allow for the collection of data while the scaled testbed is performing an emulated 0 degree, up-slope, or down-slope segment. Some parabolas will contribute to study of constant slip traction assessments as well.

Benefits: - Improved mobility tools: More accurate testbed for characterizing wheel/regolith interactions - Enhanced characterization: Greater understanding of rover capabilities to traverse varied and unknown terrain Future Customers - Future lunar rovers on NASA and commercial missions