Reviews of the Week
The Conquest of Space. By Willy Ley, with paintings by Chesley Bonestell. (Sidgwick and Jackson. 18s.)
THE possibility of being able to make a voyage to the moon has an inherent fascination for the mind of man, and has formed the theme of many romances. If the earth had no atmosphere, a projectile could be shot away from the earth if its initial velocity was greater than seven miles a second. The resistance of the atmosphere would be so great, how-ever, that a far higher velocity of projection would be needed. A much more hopeful method is to use a rocket, whose steady thrust will rapidly take it to a sufficient height for the air resistance to be practically negligible. The development of the V2 rocket by the Germans during the recent war and subsequent developmtnts in rocket flight have brought the possibility of reaching the moon mueli nearer. In the United States, using a two-step method, in which a smaller rocket was projected from a V2 rocket when at the top of its flight, a height of 250 miles has been reached.
Promising as these developmenti'are, much further technical progress in obtaining higher exhaust velocities and a greater ratio of weight of fuel to total load will be essential before there is any prospect of sending a rocket to the moon. It is premature to say—as is said on the flap of this book—that we are entering the third astronomical era ; in the first era the planets were observed by the naked eye, in the second by the telescope, and in the third era the planets can be visited. The possibilities of interplanetary flight can nevertheless now be studied as within the range of practical achievement and no longer as mere idle speculation.
Some of the problems considered in this book belong to the more remote future. It is suggested that a rocket might be tilted over, when at a sufficient height outside the earth's atmosphere, so as to orbit the earth and by meaps of telemetering instruments to send various types of informatiw to the earth, and that the unmanned orbital rocket might be succeeded by a manned "station in space," which would be not only a valuable laboratory but which might serve also as a refuelling place for rocket ships.
After an elementary discussion of the principles of rocket pro- jection and of the requirements for sending a rocket to the moon or to one of the planets, the book is devoted to a consideration of Ike physical conditions on these bodies in which the present state of knowledge on these matters is fairly summarised. The ...Ipecial interest of the book lies in the illustrations by Chesley Bonestell, many of which are in colour. One series of these illustrates the appearance of the earth. as seen from distances up to four thousand miles above its surface. Another series is devoted to the topo- graphy of the moon. A third series shows representations of the appearance of different planets._ Particularly striking are several showing what Saturn would look like when viewed from several of its satellites. Though these pictures are, of course, purely imagina- tive, the artist has been at great pains to make them as accurate as possible in their geometrical detail and, pictorially, in accordance with modern views of the conditions on the various bodies. They convey, in a much more graphic manner than any astronomical photographs can possibly do, a vivid idea of how different the moon and the other planets are, not only from the earth but also