- RM-81 Agena
The Agena (designated RM-81 by the
USAF) was a rocket upper stage developed by Lockheed for the ill-fated WS-117LUS reconnaissance satelliteprogram. It lived on to see extensive use as the upper stage/spacecraft for the Corona spy satellite program and as an upper stage on the Thor, Atlas, and Titan boosters. It was also used by the manned Gemini programto practice rendezvous and docking (see Agena target vehicle). Approximately 365 Agenas were launched between January 1959 and February 1987, when the last Agena D was launched.
It was 5 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 lbf (71 kN) thrust using
hydrazine( UDMH) and nitric acidas propellants. The engine could be restarted multiple times in orbit. The engine was particularly notable for its unusual aluminumconstruction [http://www.livingweblibrary.com/bell/agena.htm] ; the regeneratively cooled channels that cooled the throat and nozzle were formed from straight gun drillformed channels. The engine started life as the power plant for the canceled rocket-propelled nuclear warhead pod for the Convair B-58 Hustler bomber. Agena was thus known as Hustler early in its development. The manned Project Apollo Lunar Moduleascent stage engine was modelled closely on the Agena engine.
There were at least three versions of the Agena:
*A : 69 kN thrust Bell 8048 engine, 120 second burn time, used on Thor and Atlas.
*B : 71 kN thrust Bell 8081 engine, 240 second burn time, used on Thor and Atlas. Launched early
SAMOSand MIDAS military satellites and the Ranger lunar probes.
*C : Proposed but never built.
*D : 71 kN thrust Bell 8096 engine, 265 second burn time, used on Thor, Atlas, and Titan. Launched early
KH-7GAMBIT spy satellites and the two Mariner Marsprobes.
As a military reconnaissance spacecraft, much information on the project remains classified.fact |date=March 2008 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 Air Force [http://www.designation-systems.net/dusrm/app1/rm-81.html] .
* [http://www.astronautix.com/stages/agenaa.htm Agena A and discussion of the RM-81 series]
* [http://www.maniacworld.com/Gemini-VIII-Docks.htm Gemini 8 Docks with Agena] Video
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