Jumpseat signal intelligence satellites were launched by Titan-3(33)B Agena-D or Titan-3(34)B Agena-D into highly elliptic Molniya-type orbits. These orbits were very similar to those of SDS classified communications/data relay satellites, and identification of a launch in either series as SDS or Jumpseat may differ from analyst to analyst.
In their elliptical orbits they would move very slowly over the northern hemisphere for most of their orbital period, allowing interception of microwave line-of-sight communications beams. Since they would move slowly through the beams during their orbit, a constellation of such satellites was required to monitor Soviet communications throughout the day.
The satellites also probably integrated ELINT and other SIGINT functions and intercepted up- or down-links from Soviet Molniya strategic communications satellites. An additional early warning payload has also been reported
They were succeeded by the Trumpet series
|Type / Application:||ELINT|
|Configuration:||~ 20 m Ø dish antenna, HS-318 bus ?|
|Jumpseat 1 (OPS 4788)||21.03.1971||Va SLC-4W||Titan-3(33)B Agena-D|
|Jumpseat 2 (OPS 1844)||16.02.1972||Va SLC-4W||F||Titan-3(33)B Agena-D|
|Jumpseat 3 (OPS 7724)||21.08.1973||Va SLC-4W||Titan-3(33)B Agena-D|
|Jumpseat 4 (OPS 2439)||10.03.1975||Va SLC-4W||Titan-3(34)B Agena-D|
|Jumpseat 5 (OPS 6031)||25.02.1978||Va SLC-4W||Titan-3(34)B Agena-D|
|Jumpseat 6 (OPS 7225)||24.04.1981||Va SLC-4W||p||Titan-3(34)B Agena-D|
|Jumpseat 7 (OPS 7304)||31.07.1983||Va SLC-4W||Titan-3(34)B Agena-D|