The Agena Target Vehicle (ATV) was an unmanned spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques and to perform large orbital changes, in preparation for the Apollo program lunar missions.^[1]

Each ATV consisted of an Agena-D derivative upper rocket stage built by Lockheed and a docking adapter built by McDonnell. The Agena was launched from Cape Canaveral Air Force Station Launch Complex 14 on top of an Atlas booster built by the Convair division of General Dynamics. The Agena first burn would occur shortly after shroud jettison and separation from the Atlas over the Atlantic Ocean. Over Ascension Island, a second burn would place the Agena into a low circular orbit.^[1]

The McDonnell Gemini spacecraft would then be launched from Launch Complex 19, as soon as 90 minutes later. Both countdowns would proceed in parallel and required close synchronization. The Gemini would rendezvous and dock with the Agena as soon as Gemini's first orbit toward the end of the program.^[1]

The Gemini astronauts would then fly the combined spacecraft in a stabilized mode and perform a number of experiments:

• Using the Agena's attitude control system to stabilize the combination, which saved the Gemini's propellants
• Extra-vehicular activity to perform practice work on a tool panel. This required installing handrails on later flights to prevent excessive astronaut exertion.
• Refiring the Agena engine to raise the spacecraft's apogee. Gemini 11 reached a record of 739.2 nautical miles (1,369.0 km). The modified Bell 8247 engine was qualified for up to 15 restarts.^[1]
• Undocking, unreeling a 50-foot (15 m) nylon tether between the capsule and the Agena and flying in a "dumbbell" configuration with the Agena below the astronauts, to check the gravitational effect on the formation stability in uncontrolled mode. This technique is now known as Gravity-gradient stabilization.
• Using a similar tether and a few thruster bursts to rotate the two craft around each other as an early test of artificial gravity.
• After rendezvous with its own ATV, Gemini 10 performed a second rendezvous with the ATV from Gemini 8.

After the Gemini capsule separated for the last time, the Agena remained in orbit for a short time and was used to verify the command system.^{[clarification needed]}

A backup vehicle for the ATV, known as the Augmented Target Docking Adapter (ATDA), was constructed by McDonnell from the docking target and the Gemini reentry attitude control thruster assembly for use if the primary ATV failed. The ATDA was designed to allow docking, but lacked the propulsion capability of the Agena rocket. The ATDA was used on Gemini 9A, after the Atlas-Agena launch vehicle failed. However, the Gemini 9 crew could not dock with the ATDA because the nose cone shroud failed to separate properly.The Gemini aacfshgbhj.^[2]

• Project Gemini
• RM-81 Agena

 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.

• Gemini 6/Agena target vehicle 5002 systems test evaluation (PDF) December 1965
• Gemini 8 Docks with Agena Video

v t e Project Gemini
Missions	Uncrewed Gemini 1 2 Crewed Gemini 3 4 5 7 6A 8 9A 10 11 12
Astronauts	Gemini 3: Gus Grissom (command pilot), John Young (pilot) Gemini 4: James McDivitt (command pilot), Ed White (pilot) Gemini 5: Gordon Cooper (command pilot), Pete Conrad (pilot) Gemini 7: Frank Borman (command pilot), Jim Lovell (pilot) Gemini 6A: Wally Schirra (command pilot), Tom Stafford (pilot) Gemini 8: Neil Armstrong (command pilot), David Scott (pilot) Gemini 9A: Tom Stafford (command pilot), Gene Cernan (pilot) Gemini 10: John Young (command pilot), Michael Collins (pilot) Gemini 11: Pete Conrad (command pilot), Richard Gordon (pilot) Gemini 12: Jim Lovell (command pilot), Buzz Aldrin (pilot)
Components	Gemini spacecraft SC-2 Orbit Attitude and Maneuvering System Titan rocket Gemini Guidance Computer Agena target vehicle Gemini space suit
Launch sites	Cape Canaveral Air Force Station Launch Complex 19 / Launch Complex 14
Developments	Advanced Gemini Blue Gemini / Military Orbital Development System Manned Orbiting Laboratory OPS 0855 Big Gemini
Related	Charles Bassett Elliot See Manned Space Flight Network Rendezvous Docking Simulator 1966 NASA T-38 crash