Gemini 8 launched on March 16, 1966. It was the most complex mission yet, with a rendezvous and docking with an uncrewed Agena target vehicle, and the planned second American space walk (EVA) by Scott. The mission was planned to last 75hours and 55orbits. After the Agena lifted off at 10:00:00 EST, the Titan II rocket carrying Armstrong and Scott ignited at 11:41:02 EST, putting them into an orbit from which they chased the Agena. They achieved the first-ever docking between two spacecraft. Contact with the crew was intermittent due to the lack of tracking stations covering their entire orbits. While out of contact with the ground, the docked spacecraft began to roll, and Armstrong attempted to correct this with the Gemini's Orbit Attitude and Maneuvering System (OAMS). Following the earlier advice of Mission Control, they undocked, but the roll increased dramatically until they were turning about once per second, indicating a problem with Gemini's attitude control. Armstrong engaged the Reentry Control System (RCS) and turned off the OAMS. Mission rules dictated that once this system was turned on, the spacecraft had to reenter at the next possible opportunity. It was later thought that damaged wiring caused one of the thrusters to stick in the on position.