NASA astronauts Neil Armstrong (left) and David Scott (right), inserted into the Gemini 8 spacecraft prior to liftoff on March 16, 1966. March 16, 2016 marks the 50th anniversary of NASA's Gemini 8 mission, the sixth manned spaceflight conducted during the United States' Project Gemini program. The primary objective of the mission, the successful docking of two spacecraft in orbit, a first in spaceflight, was a success though the crew would experience a critical in-space system failure, forcing them to abandon the mission prematurely. UPI