![]() A minimum of five engine starts was possible. The Agena propulsion systems could be run while the Gemini was docked, allowing the GATV to be used to change the orbit of the docked pair. Propulsion was via a bi-propellant system, using unsymmetrical dimethylhydrazine (UDMH) and inhibited red fuming nitric acid (IRFNA). The primary and secondary propulsion systems were at the aft end of the target vehicle with the attitude control gas tanks, and the main propellant (fuel and oxidizer) tanks were located in the mid-section. The forward section of the Agena airframe held the guidance, flight control electronics, telemetry, command, tracking, electrical power, and propellant pressurization equipment. The GATV was a 7.93 meter long cylinder with a diameter of 1.52 meters, a dry mass of 1830 kg, and a fueled mass at orbital injection of 3228 kg. The GATV had a docking cone at the forward end into which the nose of the Gemini spacecraft could be inserted and held with docking latches. The Gemini Agena Target Vehicle was designed to be launched into Earth orbit prior to a Gemini mission and used for rendezvous and docking practice. The tether was released at 7:37 p.m., the GATV was left in a 260 x 295 km orbit. The tether tended to remain slack, but the crew believed the two craft slowly attained gravity-gradient stabilization. Gemini 12 undocked from the GATV, moved to the end of the tether connecting the two vehicles, and began the tether experiment by moving in a circular orbit about the GATV. He attached a 30 meter long tether stowed in the GATV adapter to the Gemini adapter bar. After performing tasks on the Gemini 12 spacecraft, he moved to the target vehicle adapter area and carried out a series of tasks, including use of a torque wrench while tethered. On 13 November Buzz Aldrin began a two-hour EVA at 10:34 a.m. ![]() Two phasing maneuvers using the GATV secondary propulsion system were accomplished to allow the spacecraft to rendezvous with the November 12 total eclipse over South America at about 9:20 a.m. The Gemini 12 spacecraft, launched an hour and 40 minutes later, rendezvoused and docked with GATV at 8:00 p.m. The anomaly did not affect the GATV orbit insertion, but uncertainties about the significance of the pressure drop caused cancellation of the plan to use the primary propulsion system to lift the spacecraft into higher orbit after docking with Gemini 12. During the target vehicle ascent manuever, 140 seconds after primary propulsion system initiation, a 30-psi drop occuerred in thrust chamber pressure for 1 second, then returned to normal for the remaining 42 seconds of firing. EST (19:07:58.688 UT) on 11 November 1966 into a near-circular 300 km orbit using an Atlas-Agena D rocket. The Gemini 12 Agena Target Vehicle (GATV 5001) was launched from Cape Canaveral at 2:07:58 p.m.
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