The Future of Travel Beyond the Stratosphere
By Willy Ley, 1944, published by The Viking Press (out of print)
Willy Ley was a science writer and amateur rocket scientist. There are various biographies of him online, and the broad outline is pretty clear. He was born in 1906, studied various sciences, but became a rocket buff. He wrote his first book on the subject at the age of only twenty, Die Fahrt in den Weltraum ("Travel in Outer Space"). He helped found Germany's amateur rocket society, the Verein f?r Raumschiffahrt (VfR - "Spaceflight Society") in 1927, but the Nazis came and he defected to the US in 1935. He worked as a science writer in the US, where he wrote Rockets and many other books on many subjects.
The first three chapters of the book deal with a few basic principles of rocketry, along with a lot of ancient history. Most of this stuff is pretty predictable; there aren't a lot of surprises. Chapter four, however, brings us into the 18th and 19 centuries, where things really started to happen. Ley covers many of the early pioneers of rocketry, men such as Hermann Ganswindt, Konstantin Eduardovich Tsiolkovsky and Hermann Oberth, who have been all but forgotten today. He also chronicles in good detail the various projects that the VfR worked on — including some successful liquid-fuel rockets. He also describes his work as technical advisor to Fritz Lang's Frau im Mon, one of the first movies about spaceflight.
If you look back at the history of science, you see an obvious trend. As more and more is learned, the contributions of individuals must become more and more narrow. Newton could invent optics practically singled handed, but that opportunity is no longer with us. Einstein stood, to some degree, on the shoulders of others (such as Newton), but he opened his own new branch of physics that he could explore single-handedly for a while. Novelists like Shelly, Verne and Wells, therefore built their stories around single, messianic figures who heroically wrestled truths from the universe by willpower alone. Even the early science fiction pulp writers had their mad scientists. Eventually, probably early in the twentieth century, science and engineering ceased to be an individual effort and become collaborative.
Ley was lucky enough to live through that transition. Early experiments by Oberth, for example, were individual efforts. The field grew up, however, and later work — such as that done by the VfR — was strictly collaborative:
I cannot say who invented it; it is almost impossible to tell who invented anything at the Raketenflugplatz. The Kegelduse was Oberth's invention and the first Mirak was Nebel's, but after that almost any device or development was the result of informal talks and conferences between three or four or even five or six people. We never paid any attention to the question of who had thought of what, knowing that it was a long way from our experiments to definite shapes, and knowing also that our glory was a collective glory.
By chapter seven, Ley is proposing a specific rocket for meteorological research and numbers are increasingly part of the narrative. In particular, Ley discusses in detail the fact that the exhaust velocity of a rocket is a primary determinant of its capabilities. The problem is that, with chemical propulsion, there is a limit to exhaust velocity. Practically speaking, hydrogen and oxygen (in Ley's day, hydrogen was too difficult to handle to be of use) are close the the theoretical max and they get around 4,500 meters per second of exhaust velocity.
No amount of technology or engineering will change the fact that chemical rockets are not going to lead us to a real presence in space. 4,500 meters per second just uses too much fuel getting anywhere. So you have to carry more fuel. But now you have to pay to carry the fuel around with you. It's a vicious cycle that dooms chemical rockets when it comes to interplanetary voyages.
Ley didn't know it, but electrical propulsion can change this: we already have electrical engines that thrust ions out the nozzle at over 40,000 meters per second (NASA recently tested an electrical motor on Deep Space 1). That factor of ten in exhaust velocity makes a huge difference in mass ratio: you don't need to carry around nearly as much fuel. Unfortunately, electrical engines develop a very low thrust: less than an ounce today. The good news is that they can keep that thrust up for literally months on end and the accumulated delta-V can be just as high as chemical rockets. They will never, however, lift us off the planet into space. Nuclear fusion? I kind of doubt it, unless it is as a source of electricity for an electric engine. Maybe if we could somehow engineer the reactor so that the released energy was directed back into the fusion products to move them very fast in a single direction... but we don't have any idea how to do that now.
Chapter ten lays out the needs and advantages of a space station. All of what he says is perfectly on target, but there was one surprise. When talking about he altitude that such a space station should orbit at, he says, "The late Captain Potocnik, who has already been mentioned, was in favor of a station 35,900 kilometers or about 22,300 miles above sea level. At that altitude — or distance — the station would need precisely 24 hours to circle the earth once which would mean, of course, that it would remain stationary over the same point." Personally, I had always thought that it was Arthur C. Clarke who had that idea. I googled around a bit and it turns out that Clarke only had the idea of using such a station for communications purposes, which is a little less of a leap than Captain Potocnik's.
The book ends on a optimistic note, making the case that the advances in science made in the course of conquering space might easily pay the extreme cost (which turned out to be true, arguably, if you count modern communications as a benefit). Ley knew how to sell an idea, the last pages are almost wistful.
Ley wrote other books and articles, including the successful Conquest of Space, written two years after Rockets. Nearly all of his books are out of print, however (I was lucky to pick up this edition at Half Priced Books). He also served as a technical advisor for movies and the much-loved Tom Corbett series.
Ley's whole career was an enormous boost to the idea of space travel and exploration. His books and articles simplified the concepts for laypersons and played a significant role in our exploration of space, even though he himself did little science after 1944. Ley died a few weeks before the first man set foot on the moon, in 1969. His biographies portray this as a great tragedy, but I don't think so. The first rocket that lifted off and "slipped the surly bonds of earth / And danced the skies on laughter-silvered wings" into orbit would have been his great triumph. Everything after that was gravy.