Farrah 1, 2 (P-11 4433, 4434)

Farrah 1 [NRO]

The Farrah satellites were part of a series of so called Program 11 or P-11 "Subsatellite Ferrets", low orbit ELINT/SIGINT satellites to pinpoint and characterize different Radar emitters in the Soviet Union and Warsaw pact states.

The satellites were based on Lockheed's P-11 bus, which was designed to fit on the aft rack of the Agena-D upper stage or later on a rack on the KH-9 Hexagon reconnaissance satellite. The bus contained each one or two focused payload black boxes and different antenna configurations according to payload, as well as deployable solar arrays. The satellite featured two solid rocket motors, which allowed them to rise and circularize their orbit after deployment from the host satellite. Both spin or gravity gradient stabilization was possible.

The Farrah satellites were the ultimate culmination of the P-11 project. It combined the monopulse D/F of Ursala with the TI capability of Raquel. It also included an onboard digital processor providing geopositioning to allow intercept of the most sophisticated radars.

These satellites represented a relatively significant increase in complexity due to the combination of the URSALA and RAQUEL capabilities within the constrained volume avaliable using the KH-9 as a host vehicle. They covered the full frequency range of 2-18 GHz with a monopulse DF capability for sidelobe Intercept and a capability for mainbeam TI intercept. Each satellite weighed approximately 340 kg and required upgrading of the P-11 bus for longer life and increased power capability to support the more complex payload.

Both the FARRAH I and II satellites required significantly longer development times and were plagued by problems stemming from the high packing density of the satellite. The second FARRAH satellite actually required longer to develop than the first due to the iterative redesign of the payload based on problems uncovered during the testing and on orbit operation of FARRAH I. In spite of the development problems both satellites provided successful mission capabilities once on orbit.

FARRAH was the only SIGINT satellite collector capable of collecting data in both the northern and southern hemispheres. This capability was used very effectively to provide the only SIGINT satellite support for British forces during the Falklands War.

These subsatellites were deployed directly from KH-9 Hexagon reconnaissance satellites. They used two solid-fuel kick-motors to maneuver themselves into their operational orbits after deployment.

Two P-11 based Farrah satellites have been build. Reportedly these satellites operated until 2007. Three more (Farrah 3, 4 and 5) were built on a new larger bus.