This two-person mission marked the first time two spacecraft docked together in space and the first time a U.S. mission suffered an in-flight failure that threatened the lives of the crew. After successfully docking to the Agena target vehicle, one of the Gemini's thrusters became stuck on, throwing the capsule and Agena into a tumble. The crew performed an emergency undocking from the Agena and discovered the problem was with their capsule. Neil Armstrong barely regained manual control as he fought against passing out from the G-forces. The mission was immediately aborted and landed safely in the Pacific Ocean.