Any of a series of Japanese satellites used for research into technologies to improve communications and broadcasting satellites and other future space developments. Japan's National Space Development Agency launched ETS-I (also called Kiku 1) in 1975 to acquire information about its N rocket, orbit injection, and tracking and control. ETS-VII (Kiku 7) was launched in 1997 for rendezvous docking experiments, having a chase satellite (Hikoboshi) and target satellite (Orinhime). ETS-VIII was launched in December 2006 to verify the world's largest geostationary satellite bus (see spacecraft bus) technology.