I. Introduction
The Intelligent Robotics Group at NASA Ames Research Center is building the free-flying Astrobee robots to operate inside the International Space Station (ISS) [1]–[5]. Three Astrobee robots will operate in the ISS, and three will remain on the ground for support testing. The robots' primary function is to serve as a zero-gravity robotics research platform, replacing the free-flying SPHERES satellites that have been among the most frequently-used payloads on the ISS over the past ten years. The robots will also serve operational needs: as free-flying cameras to observe crew activities, and as platforms to carry sensors to survey the ISS interior. For example, the REALM project [6] will use an Astrobee to carry an RFID reader and take inventory of RFID-tagged items.