The Agena is a manifold used American high school for space launchers. Their development was based on the knowledge gained after the first satellite launch in the late 1950s that ( eg on information ) well-defined orbits are necessary for successful use of a satellite. This could not be realized by the unique ignitable solid rocket stages used previously.
History of development
As of 1955, the military realized that a significant application of satellite technology would be to clarify the foreign territory. Therefore the program was founded WS 117L (WS for Weapons System ). Core was a photo - reconnaissance satellite whose recordings should be performed on films in capsule back to Earth (Keyhole - CORONA ). To return one had imagined that let the parachute caught hanging capsules of aircraft to allow as little as possible " enemy loss risk." Condition was a satellite that could maneuver in orbit (ie a wiederzündbares engine and a position control possessed ). In October 1956, Lockheed won the contract because it was able to draw B-58 Hustler on ( at the time already set ) developments to a controllable rocket projectile for nuclear warheads of the bomber. The U.S. Air Force designated these missiles as RM -81 Agena. The satellites were known as Discoverer. As the fuel storable combination of nitric acid / UDMH was selected. The peculiarity of the Agena upper stage was that they stayed together for the most part with the actual payload. Only parts were separated after prolonged joint flight to return or spacecraft.
The first Agenas used engines of the type Bell XLR81 -BA -3 (Model 8001 ), but most of the type of XLR -81 -BA -5 ( model 8048 ) with approximately 69 kN ( 15 500 lb ) of thrust for a burn time of 120 s the engine was gimbaled nozzles for pitch and yaw control. The Thor - Agena A launched the first optical CORONA reconnaissance satellite of the Discoverer Series ( KH -1 for Keyhole on German keyhole ). The combination of Atlas - Agena A was used called ELINT system for electronic monitoring for the Midas ( Missile Detection and Surveillance) early warning system against missile launches and Samos (Satellite and Missile Observation System ).
The Agena B presented by the extension of the tanks and the use of engines of the type Bell XLR -81 -BA -7 ( model 8081 ) is a further development of the Agena a; These engines were wiederzündfähig in vacuum, had about 71 kN (16,000 lb ) thrust, and the total burning time doubled to 240 s later variants used the engine Bell XLR -81 -BA -9 (Model 8096 ). The Thor - Agena B was partially reinstated for satellites of the Keyhole series ( KH-2/3/4/5 ) and for the Samos program. The Atlas - Agena B for Midas and Samos. Also the Ranger lunar and space probes were launched with her.
Proposed development with re -doubled tank capacity - not implemented
While the Agena A and B have been specially adapted for each mission, was created with the Agena D based on the Agena B a first standardized platform for payloads for both Thor, Atlas and Titan rockets. The payload was welcomed in the nose cone, or remained, as in the case of the Keyhole satellites, firmly attached to the Agena. Also, could be attached to the rear of the stage small secondary payloads. The payloads included, inter alia, Mariner planetary probes, but also the Gemini Agena Target Vehicles, target satellite for coupling experiments as part of the Gemini program. However, the majority of the payloads was military. With the Thor variants of the satellite optical CORONA reconnaissance satellite ( KH-4/4A/4B ) were ARGON (KH -5) and LANYARD (KH -6) started. The Atlas ( LV-3A/SLV-3 ) launched the optical GAMBIT (KH -7), the Atlas SLV -3A CANYON / Rhyolite / Aquacade satellites to electronic intelligence ( ELINT / SIGINT) in geostationary orbits. With the titanium 3B/23B/24B the optical reconnaissance program GAMBIT (KH -8) has continued. The larger titanium 33B/34B were used again for the SIGINT JUMP SEAT satellites.