Agena Target Vehicle docking seen from Gemini 8. The Agena Target Vehicle (ATV) was an unmanned NASA spacecraft used to develop and practise orbital space rendezvous, docking techniques, and large orbital changes, in preparation for the Apollo lunar missions. On 16th March 1966, the ATV was used to dock with the Gemini 8 space capsule in Earth orbit. Gemini 8 was piloted by Neil Armstrong and David Scott, and achieved the first rendezvous and docking of two spacecraft. Following successful docking, however, the Gemini 8 capsule began rolling uncontrollably. The crew immediately undocked and made an emergency return to Earth just 10 hours after launch.