After the success of Mercury, NASA realized it had to start planning for its missions to the Moon. The Gemini spacecraft was built for two men. It was still small and cramped similar to the Mercury capsule, but allowed for more freedom of movement. Project Gemini proved that two spacecraft could rendezvous (meet and dock) in space. Neil Armstrong, the first man on the Moon, was also on the first Gemini flight to dock with another spacecraft in outer space. The Gemini spacecraft did not dock with another spacecraft with people in it. Instead, it docked with a rocket called "Agena target vehicle". The last few Gemini missions were science experiments and spacewalks designed to prepare for the Apollo Program, which would land human beings on the Moon.