ELINT Subsatellites
Missions 1203, 1207, 1208, 1209, and 1212 to 1219 included Ferret ELINT subsatellites, which were launched into a higher orbit to catalogue Soviet air defence radars, eavesdrop on voice communications, and tape missile and satellite telemetry. Missions 1210 to 1212 also included scientific subsatellites.
Read more about this topic: KH-9 Hexagon