Institute of Space and Astronautical Science (ISAS)
Institute of Space and Astronautical Science (ISAS)
NEC TOSHIBA Space Systems, Ltd.
NEC Aerospace Systems, Ltd.
NEC Aerospace Systems, Ltd.
NEC Aerospace Systems, Ltd.
This is an extensive report on the attitude and orbit control systems of the Japanese X-ray astronomical observatories in space; ASCA and ASTRO-E.. ASCA stands for Advanced Spacecraft for Cosmology and Astrophysics, and was called ASTRO-D before the launch by a M-3SII launch vehicle in February 1993, meaning the 4-th X-ray astronomy mission of the Institute of Space and Astronautical Science(ISAS). The launch of ASTRO-E was unsuccessful due to the failure of the M-V rocket in February 2000 (and the mission is to be resurrected in 2005 as ASTRO-EII). In spite of the differences in the scale in weight, size and available power of the two spacecraft, the attitude control systems of the two shared very much common features that were unique to the X-ray space observatories of ISAS. This report describes the details of 1) the design approach and the configuration of the attitude and orbit control systems, 2) the control schemes or laws of the control functions involved, 3) the relevant hardware and software implementations, 4) the ground verificationtest systems and results, and 5) the in-orbit performances of the ASCA's attitude control system. The authors hope that the report could be a text for engineers who might become involved in the development or operation of spacecraft, especially for those for space-based astronomy missions.