Onward and Upward

Abstract

The failure of the first Agena-D target vehicle on 25 October 1965 left the Gemini effort in a quandary. Its role in the following year’s rendezvous and docking missions was crucial, yet its reliability had been brought into serious doubt. Efforts to resolve its woes spanned four months and the first few weeks after the failure were spent identifying the cause. Investigators quickly focused on the Agena’s engine. By November, a ‘hard-start’ hypothesis — in which fuel was injected into the combustion chamber ahead of the oxidiser, effectively causing it to ‘backfire’ had been generally accepted by the engineers. However, this problem was itself deeply rooted in NASA’s original specification for the Agena-D to be able to restart itself up to five times during a single mission.