IDCSP (Initial Defense Communications Satellite Program)
The IDCSP (Initial Defense Communications Satellite Program) was the United States military's first near-geosynchronous satellite communications system. A total of 26 IDSCP satellites were launched between 1966 and 1968 in four groups by Titan IIICs to near-equatorial, 29,500-kilometer-high orbits. Each weighed about 45 kilograms and drifted from west to east at a rate of up to 30° per day. IDCSP satellites transmitted reconnaissance photos and other data during the Vietnam War. When IDCSP reached initial operational capability, the system was renamed DSCS I (Defense Satellite Communications System I). It was succeeded by NATO and DSCS II true geosynchronous satellites in the 1970s.