Brought up to date with a second revision of the original book, published in 1955. The new material includes up to the minute data on the last two space flights of Grisson and Titov, and the latest information on both American and Russian spaceflight and on non-classified material on the Project DYNA-SOAR. New photographs as well as new text released and authorized by the military authorities. Foreword by General T. S. Power, Commander, Strategic Air Command.