A brilliant and consumingly exciting exposition of Project Vanguard is told here in layman's terms. Easily the best explanation to date, this brief handbook is as compressed and dynamic as its subject, the man-made moon which will measure 20 inches in diameter. Fired by the three-stage-rocket- with the first to act as a launching platform for the second, and the second to act as launching platform for the third, the satellite will be delivered 300 miles out in space, just beyond the earth's atmosphere. Before it reaches its destination it will have traveled at 18,000 miles an hour. It must be launched from the rocket while it spins on its own axis, at precisely the right angle to maintain a balance between centrifugal force and gravity --the two opposing forces which will conflict to keep it on its orbit. The author tracks the variance in the orbit of the satellite, explains that Minitrack, the tiny radio apparatus attached will inform scientists of the preliminary information they need prior to further space exploration, and defines the time span of the satellite. Scientists hope that it will remain in the sky for two weeks. It may remain aloft longer before it is consumed by friction with earth's atmosphere as its orbit dips closer to its perigee.