When We Left Earth (08): Gemini

David J. Shayler; Gemini: Steps to the Moon (Springer-Praxis; 2001: ISBN 1-85233-405-3; cover from a NASA photograph).

Project Mercury was pretty much "man in a can" despite some experiments; the craft was too small and the missions were too short to do much beyond the main purpose (prove you can live in space). In order to get to the Moon, we then had to test a whole range of things: can you work in a suit in space, can you rendezvous in space, can you live for two weeks in space, etc. Hence, the intermediate step between Mercury and Apollo: Project Mercury.

Shayler does an excellent job in this book, covering the transition from Mercury to Gemini, and then from Gemini to Apollo, showing the development of the craft and the missions, what missions were and were not flown (such as the lunar version of Gemini and the USAF's Manned Orbiting Laboratory—which, if flown, would have had America's first black in space well before it actually happened—let's hear it for the progressive military!). Highly recommended book!