The Gemini space flight program is often overlooked, having been eclipsed by the spectacular drama and success of the Apollo flights to the moon. Furthermore, it followed the heroic and path-finding Mercury project. However, whereas the astronauts aboard Mercury couldn't pilot their craft, the Gemini spacecraft was an agile flying machine for fighter pilots. It gave the United States the tool it needed to learn how to fly in space, and in so doing, it prepared NASA to set off for the moon. This in-depth guide offers diagrams and comprehensive appendices sure to intrigue all fans of spacecraft.