Trumpet 1, 2, 3

Trumpet signal intelligence satellites were launched by Titan-4(01)A Centaur-T into highly elliptic Molniya-type orbits. 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.

Trumpet replaced the earlier Jumpseat satellites. 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.

Amateur observations show, that all three satellites were still maintaining operational orbits in 2017 and are likely still operational.

Their successors are the much smaller "Trumpet Follow On"-satellites.

Note: The NROL designations refer to the launch, not to the payload.