Researchers at the University of Washington say they've built all the pieces for a fusion-powered rocket system that could get a crew to Mars in 30 days. Now they just have to put the pieces together and see if they work.
"If we can pull off a fusion demonstration in a year, with hundreds of thousands of dollars ... there might be a better, cheaper, faster path to using fusion in other applications," John Slough, a research assistant professor of aeronautics and astronautics, told NBC News.
Billions upon billions of dollars have been spent on fusion energy research over the past half-century — at places like the National Ignition Facility in California, where scientists are zapping deuterium-tritium pellets with lasers; Sandia National Laboratories in New Mexico, the home of the world's most powerful laboratory radiation source; and the ITER experimental facility in France, where the world's biggest magnetic plasma chamber is being built.
So far, none of those multibillion-dollar projects have hit break-even, let alone the fusion jackpot. Timetables for the advent of fusion energy applications have repeatedly shifted to the right, reviving the old joke that the dawn of the fusion age will always be 30 years away.
"The only answer to the 'always 30 years in the future' argument is that we simply demonstrate it," Slough said. And that's what he and his colleagues intend to do this summer, at their lab inside a converted warehouse in Redmond, Wash.Harnessing fusion
It's obvious that nuclear fusion works: A prime example of the phenomenon can be seen every day, just 93 million miles away. Like other stars, our sun generates its power by combining lighter elements (like hydrogen) into heavier elements (like helium) under tremendous gravitational pressure. A tiny bit of mass from each nucleus is converted directly into energy, demonstrating the power of the equation E=mc2.
Thermonuclear bombs operate on a similar principle. But it's not practical to set off bombs to produce peaceful energy, so how can the fusion reaction be controlled on a workable scale?
Slough and his colleagues are working on a system that shoots ringlets of metal into a specially designed magnetic field. The ringlets collapse around a tiny droplet of deuterium, a hydrogen isotope, compressing it so tightly that it produces a fusion reaction for a few millionths of a second. The reaction should result in a significant energy gain.
"It has gain, that's why we're doing it," Slough said. "It's just that the form the energy takes at the end is hot, magnetized metal plasma. ... The problem in the past was, what would you use it for? Because it kinda blows up."
That's where the magnetic field plays another role: In addition to compressing the metal rings around the deuterium target, the field would channel the spray of plasma out the back of the chamber, at a speed of up to 67,000 mph (30,000 meters per second). If a rocket ship could do that often enough — say, at least once a minute — Slough says you could send a human mission to Mars in one to three months, rather than the eight months it took to send NASA's Curiosity rover.Next steps
Slough's work at the University of Washington and a private-sector spin-off called MSNW has been supported by grants from the Department of Energy and NASA — including $600,000 from the NASA Innovative Advanced Concept Program, or NIAC. So far, researchers have created the deuterium droplets and heated them up to fusion temperatures. They've also tested the magnetic system for crushing ringlets of aluminum. "Now we've got to do them both together and see that work," Slough said.
The key experiments are due to take place starting in late summer, at the UW's Plasma Dynamics Lab in Redmond. If everything works, that would give the researchers the confidence to scale up the laboratory apparatus. For example, they'd use lithium rings instead of aluminum rings to increase the efficiency of the reaction.
Even if Slough is successful, it's not clear how long it would take to turn the technology into a viable rocket system. Other plasma-based propulsion systems — such as the Variable Specific Impulse Magnetoplasma Rocket, or VASIMR — have gone much further down the road of technology development. And some rocket scientists, such as the Mars Society's Robert Zubrin, think the whole idea of plasma propulsion is a potentially costly "hoax."
Despite all that, Slough's work could help kill another old joke about fusion: that it's the power source of the future — and always will be. What do you think? Please feel free to weigh in with your comments below.