Charging of the H-II Transfer Vehicle at Rendezvous and Docking Phase

The Japan Aerospace Exploration Agency developed an instrument consisting of a potential monitor and a plasma current sensor to measure the potential of the H-II transfer vehicle (HTV) against ambient plasma and the plasma environment around the HTV. In this first report on the charging measurements on the HTV-6 (sixth flight of H-II transfer vehicle), the onorbit data obtained during the rendezvous and docking phase are discussed, as well as the subsequent releasing phase. The trends observed during docking and releasing suggest the worst potential in terms of values never seen before over the full lifetime of the HTV-6. The cause is inferred to be resistance of the space station remote manipulator system as a result of numerical calculations based on simplified models of the HTV and the International Space Station.