A spaceship departs Earth on a one-way, 42-year trip to Alpha Centauri. It runs on an antimatter engine that blasts the ship out of the solar system at one-tenth the speed of light. This is not the premise for a new Ridley Scott sci-fi drama but rather the endgame of a crowdfunded spaceship project launching this month.
West Chicago, Ill.-based Hbar Technologies plans a Kickstarter effort to raise US $200,000 for the next phase design of an antimatter-propelled spaceship. The two scientists behind this design effort are a veteran Fermilab particle accelerator scientist and a former Los Alamos National Laboratory physicist and founding director of the U.S. Center for Space Nuclear Research. They originally developed it for NASA at the turn of the millennium.
Because of budget cutbacks, the U.S. space agency dropped the antimatter-driven spaceship project in 2004. But the scientists say the plans they’re developing are technically feasible—if admittedly still quite optimistic in terms of the breakthroughs needed to enable antimatter to be stored in a fuel tank.
The technology’s advocates say that antimatter would be the perfect way to power spaceflight if not for its extreme volatility—antimatter encountering ordinary matter turns both into a blast of high-energy gamma rays. The energy released by a kilogram of antimatter is more than 1000 times what you’d get from the same amount of fuel in a nuclear reactor and about billion times as much as a kilogram of hydrocarbon fuel. Gene Roddenberry, in other words, knew what he was doing running Star Trek’s ships on the stuff.[shortcode ieee-pullquote quote=""If you had a macroscopic amount of antimatter, it'd be incredibly dangerous"" float="left" expand=1]
If humans ever send spacecraft to the stars, says Hbar co-founder Gerald P. Jackson, it’s hard to imagine antimatter technology not playing some role. So, he says, let’s get started, even if the volatility problem today seems very far from being solved.
Hbar’s unmanned craft is designed around a 5-meter diameter carbon fiber sail coated in a layer of uranium. The craft’s fuel, stored in tanks 12 meters away, is an electrically neutral antimatter gas called antihydrogen, consisting of one each of the electrically negative antiproton and the oppositely charged positron.
The fuel’s storage tank sprays streams of antihydrogen gas toward the sail, whereupon the antiprotons in the gas induce fission in the uranium. Each fission reaction sends its daughter nuclei zipping into space or into the carbon fiber sail, propelling the spaceship forward.
By Jackson’s calculations, such an engine should be able to propel the craft to one-tenth the speed of light after about a year of accelerating. The radiation from the engine, because the antimatter-induced fission doesn’t need to be self-sustaining, could be kept low-level enough not to damage the spacecraft’s payload. And if it’s a manned mission, he says, the design could also be modified to distance the engine from the ship’s cabin by hundreds of meters or more, not just a dozen.
Among your skeptical thoughts concerning this scheme, one might be: wouldn’t it be easier to store charged particles instead of neutral antihydrogen, say, in a magnetic field? But to sail out to interstellar space, twice the distance of Voyager 1 from the sun, over a ten year mission Jackson calculates his craft would need 30 milligrams of antimatter. If stored as just antiprotons, however, that 30 milligram fuel tank would carry more than 2000 Coulombs of negative charge—or more than a hundred terrestrial cloud-to-ground lightning bolts’ worth. Far easier, Jackson says, to store the antiprotons as electrically neutral antihydrogen.
But how to do it, asks Thomas Phillips, research professor of physics at the Illinois Institute of Technology in Chicago. “The likely showstopper in this is being able to safely hold on to any non-negligible amount of antimatter for any extended period of time,” says Phillips. “If you’re talking about accumulating a macroscopic amount of antimatter, we don’t know how to do that. And if you had a macroscopic amount of antimatter, it’d be incredibly dangerous.”
“This is something Star Trek got right, in something they call a warp core breach,” Phillips says. “They’d lose containment of the antimatter, and the ship would blow up. And that’s exactly what would happen.”
Because antimatter annihilates regular matter in a shower of gamma rays, the containment of antimatter fuel would have to be near-perfect. In 2010, scientists at CERN managed to store 38 antihydrogen atoms for nearly two-tenths of a second. Clearly, breakthroughs are needed to ratchet fuel tank technology up to milligram or gram-sized quantities for decades on end.
“Our plan is to store tiny snowflakes of solid molecular antihydrogen,” Jackson says. “Suspended electrostatically similar to the Millikan oil drop experiment and maintaining their positions with feedback loops, this mechanism will enable storage.”
That said, Jackson notes, such a sci-fi fuel tank could be decades away. Nevertheless, he says, spinoff technologies on the road to it could be nearer at hand. Antiproton therapies would, he says, be a new frontier for cancer treatments for which regular proton beam therapies are ineffective. And because of their unrivaled ability to unmask the presence of heavy elements like uranium or plutonium, antiprotons could also detect otherwise concealed nuclear weapons.
So for all these reasons Jackson and his partner Steven Howe, who recently retired from his Space Nuclear directorship post at DOE Idaho National Laboratory, are appealing to tech early adopters, sci-fi fans, and cutting edge science enthusiasts around the world.
Jackson and Howe’s Kickstarter effort to crowdfund the next phase of their antimatter spacecraft design will be launching, Jackson says, “within a month.” And while they’re only looking for $200,000, they say this amount will allow them to optimize the thrust per antiproton in their design, to finalize the apparatus that would test their design in an antiproton-producing particle accelerator, and to begin improving the technologies for production and storage of antiprotons.
One former NASA employee who requested anonymity says he’s been following Hbar’s effort for years and is impressed with what he’s seen so far. But he says, while a starship made from Hbar’s designs could still be decades away, one further application of their technology could represent another nearer-term spinoff.
Because the Hbar design centers around optimizing a different kind of nuclear fission, in which antiprotons serve as the spark plug, the source said Hbar’s ship also explores a novel possible energy source on earth.
Antimatter-induced fission or fusion, the NASA source says, "is probably going to be developed for terrestrial power applications before we apply it to starships… But building the starship is the inspirational thing, where you get the brightest kids from around the world to say, 'Hey I want to come work on this. This is pretty cool.' I think that's where the real impetus is. And I know they're well aware of that."