Signals Intelligence (SIGINT) Satellites

Signals intelligence satellites are spacecraft designed to intercept, collect, and analyse electromagnetic emissions from sources of interest for intelligence purposes. SIGINT is commonly divided into communications intelligence (COMINT), which targets voice and data communications, and electronic intelligence (ELINT), which focuses on non-communications emissions such as radar and weapons-related signals. Much of the detail in this field remains classified; publicly available descriptions are therefore derived from open literature and reporting.

The first SIGINT satellites were launched by the US into LEO in the 1960s. Satellites called Jumpseat (reportedly codenamed AFP-711) were launched into Molniya orbit in the 1970s to intercept ABM radar signals from the Soviet Union making use of that orbit. Seven 700-kg Jumpseat satellites were launched from 1971 to 1987. ¹ Another series of seven Trumpet (also reportedly known as Jeraboam) satellites were also launched into Molniya orbit in the period 1994 to 2017 to replace Jumpseat. News reports state that the satellites monitored radio communication using antennas with diameters of 150 m. ²

The US launched the Spook Bird series of satellites into GEO, beginning in 1968. Spook Bird orbits were quasi stationary having an inclination of 3–10°, with apogees of 39,000–42,000 km, and perigees of 30,000–33,00 km such that they moved in complex elliptical trajectory covering broad regions. ³

Four Rhyolite (later called Aquacade) satellites were launched by the US between 1970 and 1978 to intercept microwave communications and missile telemetry from the Soviet Union and China. The Rhyolite series was replaced by two Magnum / Orion satellites in 1985 and 1989 to target telemetry, VHF radio, cellular communications, pagers, and mobile data links. The Magnum satellites were replaced by six Mentor satellites over the period 1995 to 2012.

In the 1970s the US also six launched Chalet (later upgraded to Vortex) satellites to intercept a broader range of frequencies. Those satellites were replaced by three Mercury (advanced Vortex) constellation in GEO in 1994, 1996 and 1998. ⁴

More than 200 SIGINT satellites have been launched in the Soviet/Russian Tselina series. France has launched several SIGINT satellites: Cerise in 1995, Clementine in 1999, and then Essaim series of four microsatellites launched in 2004. China has launched the Ji Sua Shiyan Weixing (JSSW) series of six satellites between 1973 and 1976.