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Tripos 3, 4 / Sousea 2, 3 (P-11 4420, 4421)

Tripos 4 / Sousea 3 [NSA]

The Tripos Sousea 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 Tripos and Sousea payloads were used for general search missions and had 1-meter and 0.5-meter dishes. Tripos Sousea was also used experimentally for ocean surveillance. Tripos was designed to intercept and record signals in the 4–8 GHz band, a so-called general search mission. Sousea was also a general search payload designed to intercept and record signals in the 8–12 GHz band. They would receive and record signals of interest with sufficient bandwidth to permit measurement of such parameters as frequency, pulse width, power, pulse repetition frequency, and geoposition of the emitter.

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. 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.

These subsatellites were deployed from the propulsion rack of the Agena-D stage of KH-4A Corona and KH-4B Corona reconnaissance satellites. They used two solid-fuel kick-motors to maneuver themselves into their operational orbits after deployment.

Nation: USA
Type / Application: ELINT, SIGINT
Operator: US Air Force (USAF)
Contractors: Lockheed (bus); Airborne Instrument Lab (payload)
Equipment: ?
Configuration: P-11 bus
Propulsion: Kick motor
Power: Solar cells, batteries
Orbit: 437 km × 511 km, 85.17° (#3/2); 488 km × 495 km, 83.12° (#4/3)
Satellite COSPAR Date LS Launch Vehicle Remarks
Tripos 3 / Sousea 2 (P-11 4420, Mission 7326/7237, OPS 5259) 1968-052B 20.06.1968 Va SLC-1E Thorad-SLV2G Agena-D with KH-4A 47
Tripos 4 / Sousea 3 (P-11 4421, Mission 7332/7333, OPS 8520) 1970-040B 20.05.1970 Va SLC-3W Thorad-SLV2H Agena-D with KH-4B 10

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