TAIYO (also known as SRATS) was a Japanese scientific satellite developed by the Institute of Space and Astronautical Science (ISAS), which later became part of JAXA (Japan Aerospace Exploration Agency). Solar Radiation and Thermospheric Satellite (SRATS) has experiment instruments were installed in an octagonal column configuration, measuring 75 cm in diameter and 65 cm in height. A geomagnetic attitude control system was utilized to spin stabilize the satellite while it was in a rolling wheel configuration. Metallic booms measuring 0.5 m were used to stretch four plasma probes perpendicular to the spin axis. Six thousand silicon n-p solar cells produced 15 W of power on average.