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Overview of Air Force Systems Command space programs, including the Corona project (Discoverer program) and the stabilized and restartable Agena upper stage.
“REVIEWS USAF RESEARCH AND DEVELOPMENT ACHIEVEMENTS SINCE 1954 IN MISSILES, SPACE VEHICLES, AEROSPACE MEDICINE AND REENTRY PROBLEMS.”
Reupload of a previously uploaded film, in one piece instead of multiple parts, and with improved video & sound.
Public domain film from the US National Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).
The RM-81 Agena was an American rocket upper stage and satellite support bus which was developed by Lockheed initially for the canceled WS-117L reconnaissance satellite program. Following the split-up of WS-117L into SAMOS and Corona for image intelligence, and MIDAS for early warning, the Agena was later used as an upper stage, and an integrated component, for several programs, including Corona reconnaissance satellites and the Agena target vehicle used to demonstrate rendezvous and docking during Project Gemini. It was used as an upper stage on Atlas, Thor, Thorad and Titan IIIB rockets, and considered for others including the Space Shuttle and Atlas V. A total of 365 Agena rockets were launched between February 28, 1959 and February 1987, when the last Agena D was launched.
On some missions, the payload was built directly into the Agena, which provided it with electric power, communications and three-axis stabilization… On missions where the payload was not built into the Agena, and instead separated after launch, the Agena was known as an Ascent Agena…
The final Agena launch was of an Agena-D on 12 February 1987, configured as the upper stage of a Titan 34B. In all, 365 Agena vehicles were launched by NASA and the US Air Force.
The Agena was 5.0 feet (1.5 m) in diameter, three-axis stabilized (for the benefit of the reconnaissance system cameras) and its Bell 8096 engine produced 16,000 lbs. (71 kN) of thrust using unsymmetrical dimethyl hydrazine (UDMH) as the fuel, and inhibited red fuming nitric acid (IRFNA) as the oxidizer. This is a hypergolic fuel/oxidizer combination, and as such, it does not need an ignition system. This rocket engine could be restarted multiple times in orbit, by radio command, and it frequently was. The engine was notable for its unusual aluminum construction. The regeneratively-cooled channels that cooled the throat and nozzle were formed from straight gun drill formed channels. The engine was derived from the XLR-81 propulsion unit for the canceled rocket-propelled nuclear warhead pod of the Convair B-58 Hustler bomber. Until 1959, the Agena was also known as Discoverer Vehicle or Bell Hustler. The manned Project Apollo Lunar Module ascent stage engine was modeled closely on the Agena engine.
Attitude control of the horizontal flying Agena was provided by an inertial reference package with three gyroscopes, two horizon sensors, and micro-jets using a nitrogen-freon mixture of cold gas. Pitch and roll were sensed by two hermetic integrating gyro units. A rate gyro unit determined yaw error by sensing orbital rate. Pitch and roll gyro errors were corrected from the horizon sensors, which were later supplemented by Sun and star trackers. This enabled Agena to accommodate the higher pointing stability required for better ground resolution imaging with the improved Corona cameras.
As Agena was designed to hold a fixed orientation in space while orbiting Earth, a passive thermal control system was devised.
The main source of Agena’s electrical power were Silver peroxide-zinc batteries, which from the early 1960s on were supplemented by solar arrays. An S-band beacon enable Agena to receive ground command sequences (image motion compensation, altered attitude, …), which could be stored for later execution…
more technical details on the Agena can be found in NASA TM X-1826:
“Atlas-Agena Vehicle Performance for the 1967 Mariner Venus Mission”
…The forward section is basically an aluminum structure with beryllium
and magnesium panels… The tank section consists of two integral aluminum propellant tanks… The magnesium alloy booster adapter assembly supports the Agena and remains with the Atlas after Atlas-Agena separation…
