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. At launch it carried 6360 kg of fuel and gas, and had an orbital injection mass of roughly 3252 kg. The GATV was a 7.93 meter long cylinder with a diameter of 1.52 meters and a dry mass of 1820 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. Scheduled launch of the Gemini 9 spacecraft was cancelled. The short may have been caused by cryogenic leakage in the thrust section. The exact reason for the loss of engine pitch control was unknown, data indicated that a short-to-ground occurred in the circuit for the servoamplifier output command signal. Radar data from the Grand Bahama Island station at 436 seconds after launch placed the vehicle about 191.6 km from the launch site at 29,500 meters altitude, headed north and descending. The Agena separated on schedule and both vehicles plunged into the sea about 172 km northeast of the launch site, 145 km off the coast of Florida seven and a half minutes after launch.

The vernier engines cut off at 300 seconds. It had also rolled to a position where ground guidance could not lock on.

The other booster and sustainer engine, under autopilot, worked to counter the asymmetrical thrust, but the vehicle pitched downward and after booster separation the vehicle continued flying under sustained thrust, having pitched down 216 degrees from the 67 degree nominal position, so it was flying north back toward Cape Kennedy at a climbing angle of 13 degrees above horizontal. 2 booster engine swiveled to an extreme hardover position about 10 seconds before booster engine cutoff. At 120.6 seconds after liftoff, the Atlas no. Launch of the GATV took place at 10:12 a.m. The Gemini 9 Agena Target Vehicle (vehicle GATV 5004) was intended as a docking target for the Gemini 9 mission, scheduled to launch 99 minutes after the GATV.

Agena spacecraft