Opportunities and Challenges in Space Robotics

Robotic technology has the potential to play a major part in the quest to uncover the origins of life and investigate the feasibility of long-term human habitation outside of Earth. However, the harsh conditions present in outer space, including radiation, vacuum, temperature fluctuations, and complex, unpredictable terrain, pose significant obstacles to the development and operation of robotic systems. Although a variety of robotic platforms have been created for exploration, construction, and maintenance in space, their capacity to address fundamental questions remains largely untapped. In particular, the design, construction, and control of robots that can withstand the rigors of extreme space environments remain a significant challenge. In this special section, which is building on a workshop co-organized by the guest editor at the 2020 IEEE International Conference on Robotics and Automation, we focus on the recent advancements of space robots, as well as opportunities and critical challenges of this field. In particular, we cover topics of significant interest to the field including mobility on granular terrain and bio-inspired and soft robots for extraterrestrial applications. Because research pertaining to space robotics is generally interdisciplinary in nature, we include articles not only from roboticists but also from physicists and planetary scientists. This special section includes two research articles (2100040, 2100125), two review articles (2100063, 2200071), and two perspectives (2100106, 2100195). The research article by Khajenejad et al., presents an alternative set-valued or set-membership estimation framework for estimation of unknown planetary terrain parameters based on how they affect rover motion (2100040). The other research article by Green et al., presents CASPER, a novel screw-propelled excavation system for planetary exploration and excavation. This platform employs screw propellers for both mobility and excavation and demonstrates significant excavation capability with low mass and power requirements (2100125). The two review papers in this special section discuss robotic attachment mechanisms (2100063) and soft robots (2200071) for space applications. In particular, the article by Spenko, reviews robotic attachment mechanisms for extraterrestrial applications. Specifically, bio-inspired fibrillar dry adhesives for smooth surfaces, electrostatic adhesives for smooth and rougher surfaces, and microspines for rocky and rough surfaces are discussed (2100063). The article by Zhang et al., reviews soft robotics technologies for space applications. Particularly, advantages of soft robots for such applications and potential design, modeling, fabrication, sensing, and control improvements for adapting to space environments are described (2200071). Finally, there are two perspective articles included in this special section that provide insight on soft robots (2100106), and bio-inspired multi-legged and limbless robots (2100195) for mobility on extra-terrestrial terrain. Ng and Lum elaborate on key advantages and potential changes to actuation, fabrication, and locomotion of soft robots for future planetary explorations (2100106). Li and Lewis discuss using terradynamics insights for developing bio-inspired ground robots that are effective in maneuvering on granular and rocky planetary terrain (2100195). The guest editor extends heartfelt gratitude to the authors, reviewers, and the editorial team for their great contributions to this special section. We hope this collection of articles will inspire researchers currently working in space robotics, and also encourage other researchers to engage this exciting and challenging field. Hamid Marvi