SRATS, also called Taiyo, was an aeronomy research satellite. It had an octagonal column form (75 cm in diameter and 65 cm in height), in which the experiment instruments were mounted. The satellite was spin-stabilized in a rolling wheel mode by a geomagnetic attitude control system. Four plasma probes were extended perpendicular to the spin axis by 0.5-m metallic booms. Power at an average rate of 15 W was provided by 6000 silicon n-p solar cells. The objectives of the satellite were to study the ionosphere systematically by simultaneously observing solar ionizing radiations (hydrogen Lyman-Alpha and X-rays), the ultraviolet albedo of the earth, positive ion composition, and plasma parameters such as electron and ion densities and temperatures in the ionosphere.