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The Space Station
A Personal Journey
By Hans Mark Duke University Press
Copyright © 1987 Duke University Press
All rights reserved.
ISBN: 978-0-8223-0727-3
CHAPTER 1
Beginnings
Books are important, and they can influence lives. I want to begin this story by talking about a book I received as a present on my twelfth birthday in 1941. It is a remarkable book about space travel that was written by an Englishman, P. E. Cleator, who was for many years a leader of the British Interplanetary Society. (Cleator served as the first president of the society, having been elected in October 1933.) The book was published in 1936 and is titled Rockets Through Space. (It also carries the subtitle The Dawn of Interplanetary Travel.) The book contains a good popular description of the state of the art in rocket technology in 1935 (the year the book was written), and it also includes a good technical summary of what could be done in terms of space travel once the large rockets that are envisioned in the work were built. In these sections, space stations (or outward stations as Cleator called them) and future trips to other planets were prominently mentioned.
All of this was pretty heady stuff for a twelve year old. At first, of course, I did not really understand what the technical issues were, but I kept rereading the book over the years. Slowly it dawned on me that Cleator and his colleagues were on to something really important and that I wanted somehow to be a part of it.
Much of the technical portion of Rockets Through Space deals with the early development of liquid-fueled rocket motors. As early as 1923, in his book, Die Rakete zu den Planetenraumen, Professor Hermann Oberth, who was one of the pioneers in making quantitative calculations of the performance of rockets, pointed out the advantage of liquid-fueled rockets over those that used solids—gunpowder or nitroglycerine in those days—for propulsion. The essential point was that liquid fuels could be metered into the combustion chamber in such a way that they could be controlled, and this would turn out to be critical in controlling the flight path of the rocket. Furthermore, solid fuels had a tendency to explode violently and were therefore deemed by Oberth to be more dangerous. One of the early rocket pioneers, Reinhold Tilling, was killed in just such an accident. Finally, liquid-fueled rockets were, at least theoretically, more efficient because the combustion products tended to have lower molecular weights and therefore a higher specific impulse.
In addition to his scientific activities, Oberth also participated in the organization of the experimental work that was initiated to prove out his ideas. In June 1927 Oberth, his student, Max Valier, and the engineer, Johannes Winkler, met in the then German city of Breslau (now Wroclaw in Poland) and founded the Verein fur Raumschiffahrt, which—loosely translated—meant the Society for Space Flight. The Verein fur Raumschiffahrt, or VfR as it was commonly called during the years it was active, played a critical role in the early years of rocket technology. Early on, the membership of the VfR decided to concentrate whatever resources they could muster on the development of liquid-fueled rocket motors. This decision turned out to have far-reaching consequences, not only because it was technically correct, but also because it drew a truly authentic genius, Wernher von Braun, into the world of rocketry. (Von Braun joined the work of the VfR in 1932.)
The VfR decided to build small experimental liquid-fueled rocket motors. These were called MIRAKs (for Minimum Rakete)—I guess this was the first acronym I ran across in what is now a long career in dealing with those awful things—and they were simply small rocket engines whose performance could be measured on appropriately designed test stands. What really intrigued me about the description of theMIRAKs in the book was not only that there were drawings showing how they were intended to work but also photographs of how they looked when they were running. These lent a sense of reality to the entire enterprise that other science and/or science fiction books I read at the time could not match.
In addition to the technical descriptions of the early experiments on liquid-fueled rockets, there were some grand speculations in Cleator's book. I have already mentioned the "Outward Station" (pp. 171-74) describing the work of the Austrian engineer Count Guido Von Pirquet; in the following chapter, titled "Achievement and After," Cleator describes what must be done to achieve the objective of interplanetary travel. He discusses the problem of sustaining people in space—an early description of what we today call life support systems—and then goes on to speculate that strange living things might be found on other planets, especially Venus and Mars. I was absolutely enthralled by these visions because the pictures were vividly drawn and there seemed to me to be a thread of technical credibility in the book that made the prospects real enough to touch. On rereading the book recently, I am still struck by the power of Cleator's imaginative words in that most important chapter.
I should not create the impression that Rockets Through Space is only a flight of fancy. Quite the contrary; it presented—as I have already said—a very sober technical analysis of the situation as it existed in 1935. The formidable nature of the problem was described by Cleator in a chapter titled "The Problem of Problems: Fuel." In this chapter Cleator calculates what is required to put a spaceship into an escape trajectory, go to a planet, and then return. His estimate was that using liquid oxygen–liquid hydrogen fuel—the most efficient available —a 41,000-ton launch vehicle (including fuel) would be required to make a trip to a planet with a twenty-ton (four-passenger) spaceship and to return it to earth (pp. 66-67). Fortunately, this estimate turned out to be quite pessimistic as subsequent events have proved. During the Apollo program, an 8.2-ton spaceship was sent to the moon and brought back with a rocket—the Saturn V—that had a gross takeoff weight at launch of 3,200 tons. Most of the difference is due to the much stronger and lighter materials available today that permitted a fuel-to-dry-weight ratio of 8.8 for the Saturn V as opposed to about 6.0 for Cleator's rocket. A smaller difference is that the lunar journey required a somewhat smaller escape velocity than the one Cleator assumed would be necessary for one of his interplanetary trips.
Cleator wound up his chapter on "The Problem of Problems" pessimistically, commenting at some length on the formidable difficulties that would be encountered in lifting a ship weighing 40,000 tons off the earth. He says "this is not an impossible size by any means, but the cost of transporting a rocket ship weighing but 20 tons, manned by a crew of only four persons, into space and back, assumes the terrifying total of $100,000,000." In a technological sense Cleator was pessimistic (and realistic), but as a financial forecaster he was the wildest optimist! What was most important from my viewpoint were the last few sentences of this all-important chapter (p. 68):
The trouble lies in the weakness of the fuels at present available. Without doubt, the fuel problem is the most vexing question with which interplanetary travel is faced at the moment. And it must be confessed that there is no satisfactory substitute for the oxygen-hydrogen mixture yet in sight. But as past history clearly shows, no matter how insoluble problems have at first appeared in the past, unremitting labor and patient research have eventually triumphed. It would be strange indeed if this particular problem proved an exception. And, as we shall see, there are several possible avenues of approach. The most simple and direct method, of course, is the discovery of more powerful fuels. And in this connection, we are in the tantalizing position that even present day fuels possess more than enough energy if only we knew how to release it and use it. Just as molecular energy is so freely used today, so atomic energy may bring interplanetary travel within easy reach tomorrow.
There it was. After discussing the problems with chemical fuels for the entire chapter, Cleator, in the last sentence, proposes that atomic energy (i.e., nuclear energy) might be the answer. There is no doubt at all that this is what he actually had in mind. Later on in the book (pp. 125 and 126) in a chapter titled "Ways and Means," there are two paragraphs that turned out to be of the utmost importance to me. It is worthwhile quoting these paragraphs in full:
Finally, and no matter how remote or fanciful it may seem at present, there remains the possibility of utilizing atomic energy. Those to whom the idea seems wholly fanciful should remember that in the disintegration of radium, and other radioactive substances, there cannot be the slightest doubt that a slow process of atomic disruption is going on. It is true that the process cannot be accelerated or decelerated by any known means. But the fact remains that nearly 2,000,000 calories of heat are evolved during the degradation of one gram of radium—no less than 250,000 times as much heat as is evolved during the combustion of a similar weight of coal.
There can be no doubt, therefore, but that matter contains tremendous stores of potential energy, if only we knew how to release and use it. The radioactive elements offer no hope at present, for their rate of disintegration is comparatively slow, and is not available for doing useful work. But it is not inconceivable that some means of accelerating their rate of decomposition will ultimately be found. After which, a method of disrupting the most stable elements will probably follow.
Looking back on it now, this is truly a most remarkable statement. Three years before Otto Hahn and Fritz Strassmann (1938) performed their epoch-making experiments demonstrating uranium fission, Cleator speculated on the likelihood that this event would actually occur! Furthermore, he also concluded that nuclear energy might eventually be useful as a source of propulsive power, a really remarkable leap of the imagination.
As an aside, it might be instructive to compare Cleator's view of these possibilities with those held by Lord Rutherford at about the same time. It is ironic that Rutherford, who probably did more than anyone else to clarify our understanding of the structure of the atom and its nucleus, failed to realize the potential of nuclear energy. Writing in 1937, only one year before the crucial experiment of Hahn and Strassmann, he said that "The outlook for gaining useful energy from the atoms by artificial processes of transformation does not look very promising." All of which is a classic example of Arthur C. Clarke's "first law of prophecy," which goes like this: "When a distinguished and elderly scientist says that something within his areas of competence can be done, he is probably right, and when he says that something cannot be done, he is almost certainly wrong."
Among other things, I learned from Cleator's book not to be too trusting of expert opinions—the poets and the dreamers are more often right in the long run than those of us who are too close to technical work.
I was sixteen years old (1945) when the full impact of Cleator's prediction about the potential of nuclear power for propulsion struck home. The first nuclear explosion near Alamogordo, New Mexico (July 1945), and its successors at Hiroshima and Nagasaki the following month, were potent signals for the future. By that time I thought I knew enough to evaluate for myself the technical points that Cleator had made, and I came to the conclusion that rockets capable of putting useful payloads on the moon or on other planets were at least half a century in the future. However, I believed Cleator's hint that nuclear energy might somehow be the eventual answer, and so I decided to study nuclear physics. With luck, I thought, I would live long enough to see the first men on the moon by about the year 2,000. And, I believed, that the best way I could help to hasten the day of this event would be to study nuclear physics and learn how to harness nuclear energy for rocket propulsion.
My decision to study nuclear physics was confirmed two years later (1947) when I was given another book that also had significant influence on my thinking. This one was by the prominent German science writer, Willy Ley, and it was called Rockets and Space Travel with the subtitle The Future of Flight Beyond the Stratosphere. This book was written at about the same technical level as Cleator's earlier volume, but it had very much more to say. Progress in the decade between 1935 and 1945 was truly fantastic. From the primitive MIRAKs we had come to the v-2S, and from vague speculations about the future of nuclear energy, we had the awesome reality of the atomic bomb.
Ley repeated in his book Hermann Oberth s old calculations and came to the same conclusion reached by Cleator, which was that chemically fueled rockets capable of putting people on the moon and returning them to earth would be impractically large. On pages 281-83 Ley describes what we then knew about uranium fission and speculates on how this new source of energy might be employed to drive spaceships. After discussing some of the obstacles, Ley concludes this section with the following sentence: "The important point is that we now know of a fuel which, theoretically at least, can produce ultra-fast exhaust velocities." As far as I was concerned, that was good enough. As things turned out, Ley's speculation was wrong, but I did not know enough at the time to understand the problem. The achievement of ultra-fast exhaust velocities depends on the temperature of the working fluid in the combustion chamber and is independent of the energy source used to produce that temperature. The maximum temperature depends onthe melting point of the materials of which the combustion chamber is made. Nuclear energy sources cannot exceed that temperature without melting the chamber, and, therefore, if conventional rocket technology is employed, nuclear energy is probably no better than other sources for achieving "ultra-fast exhaust velocities." Nuclear power becomes advantageous only when exotic propulsion schemes such as ion propulsion or plasma jets are employed along with nuclear energy.
Curiously enough, I was less interested at the time in the last chapter of Ley's book, which is called the "Terminal in Space." In this section of his book Ley provides a comprehensive description of what we today call the space station. Having just completed his discussion of nuclear energy in which he reached his somewhat erroneous conclusion, he starts the chapter as follows (p. 284):
Without atomic energy not very many of the goals of rocket research are within direct reach. We can, of course, build high-altitude rockets of all kinds and sizes. We can go out into space, with observers aboard, for several earth diameters. We can send unmanned rockets to the moon and we might toy with the idea of a manned trip around the moon.
Landing on the moon is already beyond the borderline of what chemical fuels can do. And to reach the neighboring planets directly will certainly require the use of atomic energy. But even when atomic energy was still thought to be centuries in the future there existed a theoretical method of landing on the moon and of going to Mars and to Venus with chemical fuels. That theoretical method was a refueling terminal in space, a cosmic stepping stone for spaceships which were too weak to reach another planet directly.
Here then is one of the major arguments for the establishment of a space station. Ley starts the chapter by describing Hermann Oberth's early work and then concentrates on recounting the work of the Austrian Count Guido Von Pirquet. Von Pirquet is the real "father of the space station" since he was the one who made the detailed quantitative calculations in 1928 (see the VfR journal Die Rakete, vol. 2, pp. 134-40) to show how the space station can be used as a staging base for more ambitious missions to the moon and to the planets. Later on, Ley foresaw the use of a space station as a laboratory in space and predicted correctly the other uses that have been developed for the space station: The space station would be a laboratory in earth orbit to be used for conducting experiments in physics, astronomy, biology, and earth observations. The space station would be a construction base, that is, as Ley put it: "The lack of gravitational strain not only permits absolutely new experiments of all kinds; it also permits the construction of new types of equipment and instruments." He then went on to describe the construction of a large astronomical telescope in earth orbit. In short, Ley, thirty-seven years ago, correctly assessed the justifications for building a space station. The arguments he made are precisely the ones that were used to persuade President Reagan to include the permanently manned space station in his fiscal year 1985 program.
(Continues...)
Excerpted from The Space Station by Hans Mark. Copyright © 1987 Duke University Press. Excerpted by permission of Duke University Press.
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