The Japanese medium-capacity CS 1 (Communications Satellite 1), renamed Sakura 1 on orbit, was an experimental communications satellite.
It consisted of a 90 rpm, spin-stabilized cylinder with its curved surface covered with solar cells. The cylinder height was 2.18 m with the antenna extending another 1.31 m along the axis. The spin axis was perpendicular to the orbit plane, but the K- and C-band antenna was despun with a pointing accuracy of better than 0.3°. This small, disk antenna was mounted on the end of the cylinder and was oriented at an angle of about 45 deg° to the spin axis. The satellite had a designed lifetime of 3 years on location near 135° east.
CS 1 was launched on 15 December 1977 on a Delta-2914 booster from cape Canaveral.
Experiments used 2.1, 2.3, 4, 6, 20, and 30 GHz frequencies for telephone and TV. Experiments studied equipment characteristics, signal transmissions, propagation characteristics, communications system operation, and spacecraft control/operation. Joint experiments with the ECS satellite in Feb. 1979 was one of the objectives.
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