Propulsion

NASA's Marshall Works on Using Antimatter to Speed Through Space

 

Harnessing a Fuel to the Stars
by Kent Faulk
News Staff Writer
2000

Source: The Birmingham News
http://www.al.com/news/birmingham/Nov2000/7-e423239b.html

November 7, 2000

HUNTSVILLE - A trip to the moon in 7.5 minutes. Mars in a day.

These cosmic treks could be possible by the end of the 21st century with the help of antimatter. When this rare substance collides with regular matter, it creates the most powerful known energy source in the universe.

Researchers at NASA's Marshall Space Flight Center in Huntsville are trying to find a way to harness this collision and use it in engines that could propel spacecraft to speeds approaching science fiction proportions.

Space & Technology

"Out of all the things we've got ... antimatter is the only one capable of providing true high-speed, interstellar-type flight," said Jim Martin, an aerospace engineer at Marshall's Propulsion Research Center. "But it's with one caveat: you have to have a lot of it." Every thing we touch or use is matter, Martin said. "Everything around us is regular matter," he said.

Antimatter is the same as matter, but reversed - like looking in a mirror, Martin explains. On the atomic level, antimatter has an opposite charge and opposite spin. When the two collide, they destroy each other and create energy.

Antimatter is scarce. Other than labs, it's usually only created when cosmic rays collide with particles floating in space.

Martin and other Marshall researchers are working on an antimatter storage system.

One theory of why antimatter is so scarce is that, at the time of the Big Bang, a bit more matter than antimatter was generated, Martin said.

The annihilation of matter and antimatter is the most energy-dense reaction known in modern physics, Martin said.

Antimatter packs 10 billion times more energy than a chemical rocket system such as the space shuttle, Martin said. "It packs 1,000 times more energy of a fission system, and 100 times that of fusion," he said.

For example, 42 milligrams of antimatter - about the size of a BB - is equivalent to all the energy of the fuel carried in the external tank of the space shuttle, Martin said. "It packs a heck of a punch."

Rocket engines using only matter and antimatter as their fuel could propel spacecraft to speeds approaching 40 percent of the speed of light - or about 75,000 miles per second.

But getting the hundreds of pounds to tons of antimatter required for such a system poses a major obstacle.

Because there's so little of it left in the universe, antimatter has to be created in labs. There are only two U.S. labs where antimatter can be created - Brookhaven National Laboratory in New York and Fermi National Accelerator Laboratory in Illinois. They produce it in large particle accelerators for use in physics experiments.

The two labs produce tiny invisible traces of the stuff each year - a whopping total of about two billionths of a gram.

At that rate it would take centuries and cost about $6 billion to produce just one microgram, Martin estimated. That amount would still be invisible to the naked eye.

So what looks to be the most likely near-term solution is a hybrid engine that uses a tiny amount of antimatter to spark a fission/fusion-based engine.

That would involve adding a small amount of antimatter - tinier than the tip of a pin - to the fission/fusion fuel mix, Martin said. The antimatter would add enough energy to initiate a fission reaction, which heats the fuel, sparking the more powerful fusion reaction, he said.

Such a hybrid system could propel a spacecraft to speeds ranging up to 558 miles per second, Martin said. That's like going from Huntsville to Mobile in less than a second, to the moon in 7.5 minutes, or to Mars in 1 day - depending on Mars' orbital position.

In comparison, chemically fueled propulsion systems such as those on the shuttle can propel spacecraft to speeds of 24,000 miles per hour. At that speed, it would take days to reach the moon and months or more than a year to reach Mars.

Before antimatter can be used for propulsion, however, key technological breakthroughs have to be made, Martin says.

One is the production of antimatter. It would take tens of billions of dollars to build a facility dedicated solely to producing enough antimatter - milligrams a year - to operate a hybrid system, Martin said. Difficult to store

But perhaps the biggest technological challenge is capturing, storing and preserving densely packed antimatter in a small container and then extracting it at the right time and in the right amount for the engine, Martin said.

Storage is what Martin is concentrating on in his Marshall lab. He is the principal investigator for the High Performance Antimatter Trap (HiPAT).

The HiPAT storage system basically has a small electromagnetic bottle where chilled antimatter can be suspended to keep it from touching the walls or banging into anything and annihilating itself.

Marshall is spending about $100,000 a year on hardware for the system, plus the salaries of the researchers.

Martin hopes HiPAT will be ready to go to one of the U.S. labs - possibly Fermi - next summer to corral its first antimatter and bring it home.

At Fermi, the antimatter is speeding around inside a rin g that's about 1,000 feet in diameter, Martin said. "You have a swarm of these things going at the speed of light (186,0000 miles a second) and you've got to slow them down and not kill them," he said.

The antimatter will have a short shelf life - about two weeks - so HiPAT would have to make a number of trips to the lab to get more. Marshall researchers have plans to build a transport system on an 18-wheeler for HiPAT so it can be easily transported.

The goal after experimenting with HiPAT is to make a better trap - one that preserves antimatter longer, increases its density, and can be used as the fuel tank for a hybrid engine, Martin said.

"The next 10 to 20 years we'll probably prove the theory ... and we'll get to the point where we can build higher density systems," Martin said.

"Then we can take it on for development of real missions."

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