Space experiments on basic technologies for a space elevator using microsatellites

We attempt to verify two basic technologies required for a space elevator using microsatellites; the tether (cable) deployment technology and the climber operation along the tether in space. Tether deployment is performed by a CubeSat called STARS-C (Space Tethered Autonomous Robotic Satellite - Cube) which will be released from the Japanese experimental module Kibo on ISS early in 2017. STARS-C consists of a mother satellite (MS) and daughter satellite (DS) connected by a 100-m tether. Its mission is focused on the tether deployment for studying the tether dynamics during the deployment with the goal of improving the smoothness of such deployment in future tether missions including space elevator. The MS and DS have common subsystems, including power, communication, and command and data handling systems. They also have a tether unit with spool and reel mechanisms as a mission system. In addition, we have been designing the next-step microsatellite called STARS-E (Space Tethered Autonomous Robotic Satellite - Elevator) under a Grant-in-Aid for Scientific Research. STARS-E is a 500-mm size satellite intended to verify the climber operation in space. It consists of a MS and DS jointed by a 2-km tether, and a climber that moves along the tether. STARS-C was launched on December 9 in 2016 and will be performed its mission early in 2017. STARS-E is in the BBM phase, and some designs are currently being fixed.