Achievements in Space Robotics Expanding the Horizons of Service and Exploration

O uter space is an ultimate field for the application of robotics technology. As outer space is a harsh environment with extreme temperatures, vacuum, radiation, gravity, and great distances, human access is very difficult and hazardous and is therefore limited. To assist human activities in space for constructing and maintaining space modules and structures, robotic manipulators have been playing essential roles in orbital operations. Moreover, expanding the horizons of exploration beyond the areas of human access, robots that land and travel on planetary surfaces have been greatly contributing to our knowledge of the solar system. New challenges are expected in the future. This article consists of three parts. In the first part, the achievements of orbital robotics technology in the last decade are reviewed, highlighting the Engineering Test Satellite (ETS-VII) and Orbital Express flight demonstrations. In the second part, some of the selected topics of planetary robotics from the field robotics research point of view are described. Recent achievements in the author’s laboratory are added as an illustrative example. Finally, technological challenges to asteroid robotics are discussed. When designing a robot to explore the surface of an asteroid, microgravity raises an interesting problem of how to stick and move on the surface. Some ideas to address these questions are introduced. Orbital Robotics Ideas to assemble space structures by a flying robot in orbit or to conduct servicing missions to existing satellites have been discussed since the 1980s. Figure 1 is an illustration describing the robotic assembling of a space structure, which was published in a National Aeronautics and Space Administration (NASA) report in 1983 [1]. One attractive scenario was to build a space station using teleoperated or autonomous free-flying robots. In reality, the current International Space Station (ISS) has not been constructed by such free-flying robots but by many hours of human extravehicular activities (EVA) with the assistance of Shuttle Remote Manipulator System (SRMS, Canadarm) and Space Station RemoteManipulator System (SSRMS, Canadarm2). Another important scenario for an orbital free-flying space robot is to retrieve and dock with an existing satellite in orbit and then conduct servicing tasks. Such tasks include replacing components, resupplying expendables, refueling propellants and repairing, rescuing, and reorbiting the satellite. These servicing scenarios have been receiving the researcher’s attention because of their potential for flexible operation of satellites, including the extension of mission life and the orbital transfer at the end of life.