the upper booster stage used for space launches on several American carrier rockets such as Atlas and Thor.

Agena is adapted for extended sojourns in an interplanetary space environment and includes restartable rocket engines and means for orbital correction and for reentry of the entire space vehicle assembly, which is not separated from the Agena rocket in orbit (see Figure 1). The weight of the

Figure 1. The Agena rocket: (1) nose cone used for docking with Gemini space capsules, (2) fairing (jettisoned after launch), (3) adapter, (4) accessory section, (5) fuel compartment, (6) nitrogen bottles for attitude control, (7) attitude control nozzles, (8) auxiliary thrusters for trajectory corrections during approach maneuvers in orbit, (9) main restartable rocket propulsion motor, (10) attitude control horizon sensor.

fueled stage approximates 7 tons; its liquid propulsion motor develops a thrust of 72 kN (7.2 tons). According to press reports, Agena was used in the launchings of the Discoverer artificial earth satellite, the secret American artificial earth satellite series, and approach and docking maneuvers in orbit.