High-speed mobility on planetary surfaces: A technical review

Despite the success so far accomplished in the robotic exploration of the Moon and Mars, the constraints associated with newly proposed mission concepts manifest the need for a faster surface prospection. Increasing driving velocities is being considered as a potential solution to the requirements introduced by these missions. This review presents the benefits and foreseeable challenges of using faster locomotive solutions for space exploration. Information is provided regarding the set of missions that would benefit most from faster locomotive capabilities. Starting by understanding the theoretical framework governing the interaction of wheeled robots operating over loose, sandy terrains, we delve into the foundation of Bekker's classic terramechanic equations—the most frequently used method to predict mobile robots off-road performance. We highlight its limitations and review the efforts that have been made to expand the range of application of these theories to dynamic wheel–soil interactions. We analyze the existing experimental evidence on the effects of increasing traveling velocities under earthbound, off-road conditions. By paying special attention to previous experiences on the lunar surface, we outline the challenges that the combination of irregular terrains and a reduced-gravity field may pose to a fast-moving exploration rover. The principles, mathematical models, experimental evidence, and experiences presented in this review are meant to aid in the identification of poorly understood and insufficiently studied aspects regarding high-speed extraterrestrial surface mobility.