NAVIGATION, GUIDANCE AND CONTROL SUBSYSTEM OF SPACE FLYER UNIT

The Space Flyer Unit (SFU) is a retrievable and re-usable platform which will be utilized for many kinds of scientific and engineering experiments in space. SFU will be launched by either a Japanese N-II launch vehicle or a United States' STS orbiter and will be retrieved after completion of missions. The functions of Navigation, Guidance and Control subsystem (NGC) of SFU are autonomous navigation and guidance for rendezvous with STS using Global Positioning System (GPS), Inertial Measurement Unit (IMU), and NGC Computer (NGCC), as well as attitude control of ordinary three-axis controlled spacecraft. In this paper the design status of autonomous navigation and guidance logic for rendezvous with STS, and in succession proximity operation around STS are discussed. And also, two critical matters concerning attitude control are stated; the first is actuator sizing compatibility for many kinds of mission operations, and the second is stabilization for flexible appendages such as solar paddles.