Some Crazy (and Not-So-Crazy) Ideas for Sending a Spaceship to Another Solar System

What's to come?
Oct. 5 2011 1:23 PM

The 40-Year Itch

Would-be space explorers, scientists, and a couple of crackpots gather at DARPA’s 100-Year Starship Symposium to try to get interstellar travel unstuck.

This article arises from Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. Future Tense explores the ways emerging technologies affect society, policy, and culture. To read more, visit the Future Tense blog and the Future Tense home page. You can also follow us on Twitter.

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Will humans ever reach the Andromeda Galaxy?

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The fastest a person has ever traveled is just 24,791 miles per hour. The three men of Apollo 10 went that fast on their way back from the moon in 1969.

The fastest a man-made object has ever traveled out of the solar system is 39,000 miles per hour—the speed with which Voyager 1, a space probe launched in 1977.*

David Neyland wants to beat these dusty, decades-old records. Neyland is a tall man, with the bushy beard of a frontier prophet and the measured tones of a midranking bureaucrat. He is both of these things. The head of the tactical-technology office at the military research agency DARPA, he convened a group of more than 1,000 at the Orlando Hilton last weekend to strategize about the next great era in space travel. The mission of the 100-Year Starship Public Symposium: to set about organizing a century-long effort to send a spaceship to another star. Neyland opened the conference to the public, drawing sci-fi fans and space geeks along with professional scientists. Ph.D. or not, all were frustrated with the lack of progress in space. As one wag in the audience would say, we should be having this meeting at the lunar Hilton. There was a sense that, for the just over 40 years since Neil Armstrong set foot on the moon, nothing new has been done.

The symposium was far-reaching, with presentations including “Modular Aneutronic Fusion Engine for an Alpha Centauri Mission” and “To Humbly Go ... Breaking Previous Patterns of Colonization.” The meat of the conference was hard science: the physics and engineering of propulsion. The dessert, which drew in the public, came in the form of sessions on space and religion (“Did Jesus die for Klingons, too?”) and panels with sci-fi writers.

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But many came for the dessert and strayed to the meat. One of the hard-core tracks (“Time-Distance Solutions: Exotic Physics”) was so popular it had to be moved to the symposium’s biggest room. The session’s moderator, John Cramer, a physics professor from the University of Washington in a plaid shirt and sport coat, said, “In times to come I predict this will be looked back on as the Woodstock of star travel.” He compared the exotic physicists to “the punk bands, the guys that break the rules in order to get laid faster.”*

There are many complications to interstellar travel, but the fundamental problem is that we need to go faster. Burning things—what almost every spacecraft so far has relied on for propulsion—would require trips that last tens of thousands of years. Nuclear rockets of various types—fission, fusion—would be faster but have their own drawbacks. Fission rockets are, in principle, technically feasible today, but launching them would be politically impossible because of the risk of radioactive contamination, if the rocket were to blow up on lift-off. The next option is solar sails, which aren’t so different from regular sails, except instead of wind, they rely on the pressure of light bouncing off them. They have the big advantage of not having to carry propellant (which nuclear rockets, like regular rockets, would have to do). A variant on solar sails, the simplest of which rely on sunlight, would instead bounce off a beam—laser or microwave—sent from earth, which has the advantage that it could be tightly focused.

After years of being all talk, a Japanese probe launched last year became the first to use solar sails for propulsion, making it to Venus in just over six months. James Benford, an entrepreneur who founded the company Microwave Sciences, gave one of the most focused talks of the conference, addressing the economics of microwave-driven sails. Because microwave ovens are cheap, he said, we could assemble an array of thousands of microwave ovens into an array to push sails. This was a great example of the reverse spin-off argument: It’s more likely that Earth-bound developments will make things in space feasible than that astronaut ice cream will take over the nation’s stomachs.

These two most obvious paths—solar sails and nuclear rockets—are methods that, if we spent a lot of money and time on developing them, would definitely work moderately well. But neither will ever be that good. The stars are just too far. What we really need is something radically different, a game-changer. For that, I turned to Kramer’s exotic physics session.

Usually musical festivals build up to the big names. But the exotic physics session opened with a rock star in the world of space geeks: Marc Millis.* Millis was famous for having persuaded NASA to run a short-lived “breakthrough propulsion physics” project from 1996 to 2002. During my subsequent interview with him, we were interrupted three times by attendees eager for Millis’ autograph. He now runs his own outfit, the Tau Zero Foundation, which scrapes by on donations. He also literally wrote the book on the subject: Frontiers of Propulsion Science, which has whole sections on how to dissuade crackpots.

While careful not to overpromise, Millis is trying to think of ways that a spacecraft could be propelled without fuel. “You have to pick something completely different,” he says. “Why don’t we go back to the fundamental physics and try and find solutions around that?” One of his ideas is to try to push against the universe. “You move one way and the universe moves the other way. If you start thinking about this, your head starts spinning. What,” he asks, “are you pushing the universe relative to?”

Throughout the weekend, there was some disconnect between the space-curious members of the public, eager for visions of Star Trek futures, and the scientists engrossed in the nitty-gritty. Millis was followed by Harold “Sonny” White, from NASA’s Johnson Space Center. While talking about the field equations of general relativity, he had the excitement of someone describing a running back juke around a defender. When he segued into the Chung-Freese metric, the woman next to me, a matronly type with dyed red hair, turned to her companion and asked, “Do you understand this?” He had a bushy mustache and sneakers, and if nerdish looks were any guide, looked like he should. He wrote his answer on a piece of paper, a scrawled “No.” It’s good to get the public excited, but the best way to do this is to actually do exciting things, not to have a deliberate strategy of public engagement that leaves lay audience members baffled in Orlando conference rooms.

White is currently designing an experiment to test whether he can demonstrate a small gravity-distorting effect in the lab. “This is highly speculative physics. It may not have any basis in physical reality,” he cautioned. “Nobody get excited. It’s still very, very hard.” That was the line between the serious types and the crackpots—the serious types had crazy ideas, too; they just didn’t forget that their ideas were probably wrong. “You want to tackle the challenges that make your peers feel uneasy,” Millis says.

Millis, White, and their colleagues are trying hard to strike a balance; they know they must be both audacious and methodical. Others at the conference weren’t trying as hard.

On Sunday morning, the guys from Sol Seed (“Bringing Life Even Unto the Galaxy”) passed out fliers stating four rather ambitious, and divergent, goals. The first is to build an “eco-village community in Portland,” while the fourth is “contributing to the destiny of life: spreading beyond Earth to take root amongst the stars!” Surprisingly, though, only one guy ranted about UFOs. (“I’m not talking about the crazy people. I’m talking about solid military evidence, CIA, DIA.”) He left the room quietly when the panelists refused to engage him.

Then there were those who weren’t crazy, but weren’t helpful, either. One presenter vaguely said that it would be good to be able to communicate faster than light. He was riveted by his own slides, which said, “This problem appears insoluble.” Toward the end, he mentioned the potential military application of his non-existent technology: It would work underwater. This is a bit like saying that if you were immortal, not having to worry about a long wait for a table at Applebee’s would be one of the important benefits.

Tufts University’s Ken Olum had the biggest beard I saw at the conference, which is saying a lot. His beard goes around a big U along the whole of his head, giving him a sort of upside-down halo. He looks like I imagine an alchemist might. But he wouldn’t like that comparison. “We should not be alchemists,” he told the conference. “They wanted a goal and that’s what they thought about. After a while they were doing nothing useful. They were replaced by chemists who had the desire to learn about the world as it is, and not the desire to do some particular thing.”

Speaking of misguided desires, a subsequent panel of science-fiction writers engaged in a long and pointless argument about the sociology of space colonies: It had all the substance and weight of a nuanced public policy debate, except that the dilemmas they were talking about were fictional. Michael Waltemathe, a young German academic with a pink tie, talked about religion and space colonization. Apollo 14, he told the audience, had taken 100 microfiche Bibles to the surface of the moon and back. This made him wonder how many bishops a space colony would have to take along to uphold apostolic succession. “Since I’m a Protestant,” he said, “I would take all of them.” That was the problem with a conference that deliberately tried to cultivate dreamers: They started planning the wedding before they’d even asked the girl out.

As the symposium drew to a close, James Benford sounded a note of optimism with a hint of longing: “We’ve been asking how to build starships. If we can’t, the rest of the questions are moot. The answer, I think, is that we can.” No one expects more money from DARPA, or from NASA, but they really are convinced that change is coming. Outside the main session, I stood talking with Millis. He took out a recent article he wrote for the Journal of the British Interplanetary Society. There was a triptych of rockets: a NASA rocket, Virgin Galactic’s SpaceShip One, and SpaceX’s Falcon rocket. “Fail!” he exclaimed when he pointed to the NASA rocket. “We are at the threshold of a sociological change,” he said: Space is about to be opened up to private industry in a fundamentally new way. If industry lives up to the hopes of those assembled in Orlando, maybe the fastest human beings in history will soon be traveling toward something instead of back to Earth, like the Apollo 10 crew.

Corrections, Oct. 6, 2011: This article originally mischaracterized Voyager 1 as the fastest man-made object. Voyager 1 is the fastest objet to travel outside of the solar system; the New Horizons probe is the fastest-ever man-made object. (Return to the corrected sentence.) This article originally misspelled the last name of John Cramer. (Return to the corrected sentence.) This article also originally misidentified Marc Millis as Michael Millis. (Return to the corrected sentence.)

Konstantin Kakaes is a Schwartz fellow at the New America Foundation and the author of the e-book The Pioneer Detectives: Did a Distant Spacecraft Prove Einstein and Newton Wrong? Follow him on Twitter.