Antimatter Fuel for Rocket is Theoretically Possible

With antimatter in the tank, taking the family rocket out for a spin to the nearest M-class planet would be a relative breeze. Miniaturized antimatter fuel might consist of a thumb-sized canister with an energy source no bigger than an aspirin and no need of replenishment for hundreds of light-years -- or, locally, tens of millions of intra-solar-system miles.

Turning a Positive Into a Negative

Producing antimatter is a difficult expensive process. 

Ever since the 1930s, scientists have known of the existence of a twin to ordinary matter. Antimatter has the same mass but opposite spin and charge. Put matter and antimatter together and it's like Einstein said, E=mc2 -- 100-percent energy conversion. Luckily for normal-matter humanity, there doesn't seem to be too much antimatter left over from the Big Bang to cause random ultra-explosions.

Cosmic paucity, however, hasn't stopped human manufacture. More antimatter is now being produced artificially than at any previous time in human history. So where are the next-generation, Star Trek-like antimatter rocket engines? Only in the imaginations of futurists, and definitely not on the drawing boards, retort researchers.

"The power we use now to make antimatter is close to a billion times more than we can produce [with antimatter]," said Dave McGinnis, an antiproton expert and department head of the Antiproton Source at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois. Fermilab is one of the world's leading makers of antimatter for scientific study. "It's remarkably inefficient and just not economical. That's the bottom line and the reason we don't yet have an antimatter rocket." 

 

Changing the equation

Hoping to change the antimatter cost equation is Chicago-area startup Technology Antimatter Production LLC, helmed by former Fermilab accelerator physicist Gerry Jackson, now the company's president. Jackson says new techniques that he and his seven collaborators are devising could lead to more efficient techniques. Within the decade, Technology Antimatter --- using the Fermilab particle accelerator under a cooperative business agreement with the laboratory --- could produce 1,000 times more antiprotons than are currently manufactured annually at Fermilab, and at less expense.

"Right now antiprotons are being generated for high-energy physics experiments," Jackson said. "The requirements are very restrictive. It 's possible to modify the equipment to vastly increase antiproton numbers."

Should the company be able to solve the twin problems of storage and use --- two major problems, Jackson admits --- the market in medical applications, such as diagnostic scanners, could be substantial. But antimatter propulsion is also a possibility. Technology Antimatter will partner with NASA's Marshall Space Flight Center to capture and store antiprotons in a Marshall apparatus known as a High Performance Antimatter Trap, or HiPAT. Propulsion experts will use the trap to study ways of making antimatter engines a reality. If they're successful, given the enormous amounts of thrust potentially available, trips to the Moon could take minutes and Mars would be a day or so away.

"Marshall is looking at spaceflight 30 to 40 years out," Jackson said. "Now is the time to do the 'R and D' for those missions. We'll be providing them the fuel they need for those engine tests."

Radical breakthroughs?

Gerald Gabrielse, one of the world's foremost experts on the manufacture of antihydrogen and chair of the Harvard University physics department, remains skeptical. He leads an international collaboration to produce and store antihydrogen in special facilities at CERN, a physics research complex located in Geneva, Switzerland. Assuming you were able to collect all the antiprotons ever made, Gabrielse points out, heating something as small as a cup of coffee would prove impossible. Antimatter's most likely future is as a subject for scientific investigation, not as fuel for futuristic space vehicles.

"Making antimatter fuel for one rocket is theoretically possible. But I don't see it happening anytime soon," Gabrielse said. "There are significant problems I don't know how to solve. A fuel that requires more energy to make than it releases is not much of a fuel source. It' s pretty clear no one is going to make a rocket engine fueled by antimatter in the next 10 years."

Skepticism doesn't faze Gerry Jackson. He concedes that antimatter-driven spaceflight may be decades away. Nevertheless, given the rate of technological innovation and unanticipated ingenuity, he thinks radical breakthroughs in antimatter technology and near-term applications may be closer at hand than even advocates dare hope.

"You would never have thought of [desktop personal] computers when the transistor was invented. That's probably where we are now," he said. "It's easy to say an idea is crazy, but you really need to sit down with present technology and extrapolate it forward. Right now, of course, no one can build an antimatter engine. But 10 years down the road, and I think we're going to start to get close."