NASA Researching Antimatter Engines

dbolger writes: "CNN has a story about how scientists at NASA's Marshall Space Flight Center in Huntsville, Alabama are researching ways to use antimatter to fuel missions to Mars and beyond within the next 50 years. It very light on technical details, but does give an interesting look at current and future potential uses of antimatter."

Comments

antimatter versus antiatoms; containment

[bcrowell]

The article doesn't distinguish between antimatter and antiatoms. Antimatter is easy to produce, and even occurs naturally in cosmic ray events and the decay of natural radioactive substances. Antiatoms are a different story. The simplest antiatom is an antiproton plus an antielectron, which makes an antihydrogen. Last I heard, only about 10 antihydrogen atoms had ever been made. The article refers to antimatter being made in microgram quantities; if so, then this is a /major/ advance over the state of the art ~5 years ago.

Containment depends on what form it's in. Slashdotters have been referring to Penning traps here. Well, a Penning trap only works for charged particles, not neutral atoms, and it only traps one sign of charge -- you can't trap both + and - particles in the same Penning trap. Therefore, I don't think a Penning trap would be suitable for storing even microgram quantities of bulk matter; if you have matter or antimatter in bulk quantities, it has to be electrically neutral. I think the posters were confused between containment of plasma and containment of antimatter.

Containing antimatter, if you had it in bulk quantities, would be much easier than containing a plasma, since it doesn't have to be superhot like a plasma. You have to have an extremely good vacuum, however, because any matter that finds its way in will annihilate with the antimatter. I doubt that even the vacuum of interplanetary space would be good enough.

Devil is in the details

[StefanJ]

Antimatter is a very efficient way of storing energy, but using that energy to power a rocket won't be easy.

The job of a rocket is to create a stream of really fast particles moving in a particular direction. The faster, the better. Newton's Third Law and all that.

Those particles could be gas, accelerated with good old heat, ions accellerated with an electric field, or plasma.

Here's the rub: matter-antimatter reactions produce really energetic particles. Gamma rays, like. They kind a whiz right through the fuel you want to heat up. And the "combustion chamber." And the crew, and . . .

I read up on antimatter and fusion propulsion at grad school. (There's a suprising amount of good material out there; do not rely solely on the word of popularizers like Robert Forward!) The most-fully-realized antimatter rocket was kind of clunky. In the middle of the "combustion" chamber would be a cylinder of dense tungsten alloy full of tubules. A slow but steady stream of antiparticles are shot into the cylinder, which heats up. Hydrogen in pumped into the tubules; it heats up and "whoosh."

The disappointed bit: The specific impulse would "only" be about 5,000 seconds. This is about ten times what a liquid-fueled motor is capable of, and about 50% better than the little ion motor tested out on Deep Space One, but it's not amazing.

The most promising use for animatter: Using it as part of a fusion drive. A antimatter-catalyzed fusion drive described in the text I read was predicted to have a total impulse of something like 130,000 seconds. THAT is impressive. The thrust wouldn't be high, but you could keep it up for months and months.

What we might see are ships that use the direct-thermal sort of antimatter motor for getting a ship going (e.g., reaching escape velocity out of the Earth / moon system), then the fusion drive would be used to provide constant acceleration to speed up the trip.

Stefan

Sorry, you're just wrong.

[RobertFisher]

I would also say, however, that I think the days of NASA are numbered and I wouldn't mind the complete dismantling of the entire agency. They are too stuck in the past (reliving the glory days of Apollo), and are actually doing more harm than good now for giving me or my children the opportunity to work and live in space.

First, you seem to have the misconception that NASA is entirely devoted to the manned exploration of space, and that moreover, they haven't done anything new since Apollo.

You are simply misinformed. You're just plain wrong.

Take a look at some of the projects that NASA has been up to recently, and then see if you can still claim they are "living in the past" :

Space Observatories
Chandra X-Ray Observatory

Hubble Space Telescope
Earth Observatories
Advanced Spaceborne Thermal Emission and Reflection Radiometer"
Solar System Missions
Mars Rovers
Astrophysics Research
Origins Program
And a sampling of the slate for future missions :

The Terrestrial Planet Finder

Deep Impact Comet Mission

Dawn Asteroid Flyby"

As you can see, NASA is not just about flying shuttle missions. They are actively sponsoring research in the space sciences and astrophysics across the board... from the study of our own planet, to the solar system, other stars and galaxies, and the cosmos as a whole. Their missions support the development of new technologies (which, unlike the previous poster seems to believe, are not limited to propulsion technologies, but include a wide array of telescopes and detectors across the entire spectrum). And NASA also actively supports scientists at all levels -- from graduate students through postdocs and faculty.

I think we live in a unique time where we as a species are really beginning to understand what makes up the universe, and how it works. I'm quite
confident that when the history of science of the 20th and 21st centuries is written, NASA will have played an enormously significant role in that process of discovery.

Bob