[Illustration: 31. Thor-Agena launch vehicle and its satellite
payload before launch.]
The Agena launch vehicle has been an integral part of both unmanned and
manned space programs. Flown as an upper stage on Thor and Atlas
boosters, Agena orbited an impressive roster of spacecraft including the
Echo communications satellites, the Ranger and Lunar Orbiter Moon
probes, and the Mariner vehicles that traveled to Venus and Mars.
As the target for docking experiments during Project Gemini, Agena made
substantial contributions to the eventual success of the Apollo program.
The vehicle earned the distinction of being the first to place a payload
in polar orbit, and was also the first to achieve circular orbit. The
Agena engine was the first which could be stopped and restarted in
space.
The Agena launch vehicle was developed and manufactured by the Lockheed
Missiles and Space Company for the United States Air Force.
Length 7.1 m. (23.25 ft.)
Diameter 1.5 m. (5 ft.)
Weight Empty 674 kg. (1484 lb.)
Fuel Unsymmetrical dimethylhydrazine
Oxidizer Inhibited red-fuming nitric acid
Thrust 7260 kg. (16,000 lb.)
The Agena-B is from the United States Air Force and the Lockheed Missile
and Space Company.
[Illustration: 32. The Agena Target Docking Vehicle seen from the
_Gemini 8_ spacecraft during rendezvous approach.]