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It may be possible to propel a vehicle weighing several thousand tons to velocities several times earth escape velocities. A circular disk of material, which is called the pusher, is connected through a shock-absorbing mechanism to the ship proper, which is above the pusher-shock-absorber assembly. Nuclear bombs, which are stored in the ship, are fired periodically below the pusher. Each bomb is surrounded by a mass of propellant. As a result of each explosion, the propellant strikes the pusher and drives it upward into the shock absorbers, which then deliver a structurally tolerable impulse to the ship.
—Feasibility Study of a Nuclear-Bomb-Propelled Space Vehicle, contract between the United States Air Force and General Atomic, June 30, 1958
“You, there! Big man! Wait!” Leo Szilard moved quickly to catch up with the broad-shouldered fellow.
“Yes?” The voice was accented and higher pitched than one might have expected based on his size.
“Sprechen Sie Deutsch?”
“Ja.”
“Ah, sehr gut,” said Szilard, and he continued on in German. “Then you must indeed be him!” He put his hands on hips. “Well, well, well! Wernher von Braun, at last!”
The “big man,” although stocky, had nowhere near Szilard’s girth, but he was a head taller than the Hungarian. “And who might you be?”
Leo was surprised. “I’m Szilard, that’s who! Surely you know!”
“Oh,” said von Braun, sounding unimpressed. “What are you doing here in San Diego?”
“One might ask the same of you. I heard you were in Texas with your rockets.”
They were out front of the circular technical library that was at the heart of the new General Atomic facility in Torrey Pines. “Oppenheimer had mentioned what they were working on here,” von Braun said. “Of course, I’d seen Ulam and Everett’s report back in 1955, but I hadn’t realized anyone had taken it seriously.”
Leo knew that report well: he and his Compact Cement teammates back in Princeton had spent a lot of time discussing it. Although its title was On a Method of Propulsion of Projectiles by Means of External Nuclear Explosions, and although it made no mention of manned space travel, the applicability of the proposed technique for that goal was obvious. The work being done here—dubbed Project Orion—had grown from Stanislaw Ulam’s idea, first put forth right after the Trinity test, of using exploding bombs to propel spaceships.
“Oh, they take it very seriously indeed,” said Szilard. “Freeman Dyson has come out here from the Institute for Advanced Study as our Arbor Project emissary; he’ll be part of Orion for at least this academic year.”
“Dyson, yes. A sharp mind, that one.” Von Braun looked down on Szilard, and perhaps not just literally; Leo knew the German, essentially an engineer, had little use for the kind of luftmensch thinking Szilard was famous for. “And you are here why?”
“Not to stay, I assure you,” said Leo. “Well, not to stay here at General Atomic, although they have engaged me as a consultant.” G.A. was the division of General Dynamics devoted to “harnessing the power of nuclear technologies for the benefit of mankind.” “But I could see making a home in La Jolla. Jonas Salk and I have plans to create an institute for biological studies, and I’m going to suggest we build it there. Such a beautiful area!”
“Biological studies?” said von Braun in a tone that suggested Szilard had uttered the equivalent of astrology.
“Yes—the science of life! Getting humans off this earth is only one part of the solution; making mankind more suitable for space travel and for living on other worlds surely is a key component, too.”
“Ah,” said von Braun. The summer sky had cirrus graffiti scrawled across it, and there was a tang of salt in the ocean air. “So, then, what do you think?”
“Of Project Orion?” Leo raised his eyebrows. “It has gumption, I’ll give it that.” He pointed at the two-story library, looking like a giant white checkers piece. “Ted Taylor tells me that this building is a hundred and thirty-five feet in diameter, precisely what they envision for their 4,000-ton spaceship design. That’s five times as wide as your biggest planned rocket, no? The thing they intend to build is gigantic!”
“Girth,” said von Braun, “isn’t everything.”
Leo chuckled. “Perhaps not. But their propulsion scheme? Popping an endless string of small fusion bombs out a trapdoor like seeds from a watermelon, and exploding them to push a space vessel ahead. Visionary.” He put a hand on his chest. “I contributed one idea myself. Have you ever used a Coca-Cola machine?”
“Of course.”
“So efficient: you select what you want, and a mechanism neatly delivers the bottle. I said that’s how they should move their bombs from storage aboard the space ship to the trap door, selecting from a variety of bomb sizes depending on the propulsive need. Dyson loved the notion; he tells me engineers from Coca-Cola in Atlanta will be here next week to show them how it’s done.”
The taller man’s eyes narrowed. “I hear you have Oppenheimer’s ear. Will you tell him you favor this project?”
“Over your rockets? Come now. You yourself must know that Orion is far more efficient.”
“But rocketry is proven technology!” declared von Braun. “This is moonshine.”
Szilard smiled. “Rutherford used the same word to describe getting lots of energy by splitting the atom, but we did that. I used the same word to describe H.G. Wells’s notion of atomic bombs, and then we built one.”
“Of course it was built. It was simple, straight-forward engineering, just like my rockets—”
“Your rockets!” Leo made an exasperated sound. “You want everyone to believe that all you ever cared about was building rockets for space travel—don’t deny it! But what you were actually building—what you were charged with building—were missiles to fly just a thousand kilometers from Germany to Britain. Yes, sure, that’s something chemically fueled rockets are good for—tiny hops! But such things are all but useless for making trips to other planets.”
“You need to read my novel Project Mars. I can send you the manuscript or—”
“I know your ideas for manned space flight, but—”
“They will work! They will all work!”
“Sure, but on a scale wholly inappropriate to our task. Even you must agree! Dyson walked me through it all. Chemical rockets have exhaust velocities of about three kilometers per second, and to increase velocity, you need to use stages—big fuel tanks that are dumped, in order from bottom to top, once emptied. I’ve seen your designs; that’s precisely what you propose. And you need n stages for every velocity increment of 3n kilometers per second, right?”
“Ja.”
“Getting to low earth orbit takes two rocket stages; high earth orbit, three stages; just going to the moon, four; and a lunar round-trip, as many as five!”
“Yes, but—”
“But what? It’s really a simple geometric progression, roughly speaking, in terms of how much of one of your rockets can be anything but fuel. In a chemical rocket, the ratio of fuel to payload is about four to the nth power, so the ratio of fuel to payload is sixteen pounds to one pound for low earth orbit, right? And sixty-four to one for high earth orbit, no? Then 256-to-one to go one way to the moon, and a whopping 1,024-to-one for a lunar round-trip. To put a hundred pounds of payload on the moon—a very small man, much thinner than me and much shorter than you!—and bring him safely back to the earth, you’d need roughly one hundred thousand pounds of chemical fuel.”
“Yes, yes,” said von Braun. He looked around, making sure no one else was near enough to overhear, then added, “But we’re in luck—if you can call it that—because we’re not planning round-trip missions. We’re talking about an exodus; we’re talking about colonization ships.”
“All right,” said Szilard. “Still, the farther you want to go from good old terra firma, the more rocket fuel you’ll need. On the other hand, with this Orion notion, exhaust velocity will be thousands of kilometers per second instead of just three, you only need one stage, and the ratio between fuel mass and payload stays pretty much constant no matter how far you go. Whether you just want to make it into orbit or trek all the way to Alpha Centauri, more than one-tenth of your ship’s mass can be payload.”
“If their mad scheme works. I, for one, prefer the tried-and-true instead of something cobbled together out of soft-drink-vending machines and giant springs.”
“Dyson says Orion will be ready to take people to Mars by 1965—and to the moons of Saturn by 1970. Can you do that with your vengeance weapons?”
Vengeance. The “V” in V-2. “Ah, I see why you are so riled up,” said von Braun, nodding as if a conspiracy had at last been revealed. “You had friends in London, yes?”
And that just made Leo angrier. Sure, he’d lived in London; it was there, at an intersection on Southampton Road in 1933, that he’d first conceived of the nuclear chain reaction. But he’d balked when Jimmy Byrnes had suggested Leo’s opposition to atomic bombs was because he worried about his native Hungary, and he didn’t like this hulking Junker implying that a selfish impulse drove him now.
“I’m looking for the best solution for all mankind,” Leo said. “You—you are looking for the best solution for von Braun!”
“Well,” said the German, “time will tell—and may the best machine win.”