Gemini IV was the second of 10 manned Gemini missions,
which perfected the techniques of spacecraft rendezvous and docking and
demonstrated that astronauts could withstand prolonged weightlessness
for the planned Apollo missions to the Moon.
Gemini Capsule
On 3 June 1965, astronaut Edward H. White II became the first American to perform an Extra Vehicular Activity (EVA) or spacewalk from this Gemini capsule. His crewmate, James A. McDivitt, remained inside the spacecraft.