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In this paper, on-orbit joint flexibility experiments using ETS-VII (Engineering Test Satellite VII) robotic arm are discussed. Considering manipulability of the robotic arm, the arm vibration due to the joint stiffness may influence on the berthing manipulation. The vibration of the robotic arm mounted on a satellite is characterized as follows, 1) coupling between the arm and the satellite attitude vibration, and 2) transition of the arm natural frequency according to its posture changes with the inertial parameter variation. The experiments are planned to evaluate these vibration disturbance. Using telemetry data detected by FTS (Force Torque Sensor) attached to the end-effector, the arm natural frequencies and the transitions of the arm vibration amplitude are analyzed. And the validity of the simulation results is demonstrated.

“TSUBAME” is a university-built small satellite mission to measure polarization of hard X-ray photons (30-200 keV) from gamma-ray bursts (GRBs) using azimuthal anisotropy of Compton-scattered photons. Polarimetry in the hard X-ray and soft γ-ray bands should provide crucial information for understanding the high-energy emission mechanisms and the distribution of magnetic fields and radiation fields in the astrophysical sources. TSUBAME has two instruments: the Wide-field Burst Monitor (WBM) and the Hard X-ray Compton Polarimeter (HXCP). The WBM determines on board the direction of the burst occurrence with an accuracy of 10 degrees, then using a high speed attitude control device, the HXCP is pointed to the GRB within 15 seconds after the burst occurrence to promptly detect polarized X-ray photons from the GRB. We present an overview of the TSUBAME mission, its estimated scientific capability for detecting GRBs and measuring their X-ray polarization, development of multi-anode photomultiplier tubes that use ultra bi-alkali photocathodes, and the future plans of this mission.