Slashdot Mirror
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."
There is something definately wrong with the picture on cnn.com. This picture looks very wrong someone must have been thinking bad thoughts at the time.
I've never understood exactly how you would contain antimatter until it is used...Is it contained in some kind of electromagnetic field, or is this all still theoretical? I thought that antimatter was immediatly annilihated due to its inherently volatile nature when it is produced.
Anyone know any more details on how one would actually build up a gram of isolated antimatter?
There's an older (1999) article on nasa's site with a bit more technical detail.
Hogsback
Yes, antimatter has mass just like normal matter. Indeed, this is one of the things that distinguishes gravity from say electric charges. Gravity is always attractive, mass is always positive. With electric charge, positive and negative, and repulsive and attractive forces are possible and seen daily.
One can see this from the fact that matter has energy. E = mc^2 and all that. Antimatter has energy also, meaning you cant 'borrow' energy from the universe by creating some antimatter with negative energy. The flip side of this is that when you bring antimatter and matter together, they annihilate each other, liberating all their energy stored as mass into a burst of radioactivity. This presumably is the source of energy for the engines (or whatever) discussed in the article.
dominionrd.blogspot.com - Restaurants on
I thought you needed a reactor core with dilithium crystal to make a matter-antimatter reaction possible. Can NASA produce dilithium crystals yet ? and visors for the reactor core technicians ?
I was at MSFC on a business trip a while back, and talked to the guys working on Gen2, Gen3 and later RLV design. Basically what the lead engineer told me they do is "assume we have really cool technology that meets certain specifications" and work backward from there to figure out how the rest of the vehicle be designed.
While I'm sure there might be one or two people actually doing research into antimatter, most of the work they do is just assuming *someone* will come up with the necessary technology by the time they have to build something.
Cell phones = communicators
Babelfish = universal translator
Taser(tm) = Phaser on stun
2-way videophone = Screen on the bridge
PC = Enterprise computer terminal
Now antimatter propulsion.
Was this guy good or what?
Computer Science is no more about computers than astronomy is about telescopes. --E. W. Dijkstra
Am I the only one thinking antimatter costs more energy to produce than you get out of it?
Secession is the right of all sentient beings.
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.
Find free books.
I would be rich... (this abused phrase notwithstanding).
/. readers) would consider archaic. I mean, 16 bit processors are finally being used for many missions and 8 bit processors are still common.
Seriously, there are so many futuristic NASA research projects (most of them in the $10,000 to $100,000 range). They cover everything from anti-gravity to blowing bubbles (liquid soap bubbles).
I personally think this is what NASA does best, and the results from these research grants are quite interesting. It is also very unlikely that NASA will ever do anything with most of these research projects.
{Rant Mode On}
Just for an example, there hasn't been a new propulsion technology for manned spaceflight since the 1970's (mainly due to politics... including internal NASA stuff too), and even the robotic probe missions are using what most geeks (and
I would consider myself to be a major NASA supporter, and I do vote for congressmen that are supportive of the space industry. 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.
As a percentage of the US Federal budget, NASA is now totally inconsequential. During the 1960's NASA was second only to the Department of Defense. Now, NASA doesn't even show up except on a list of miscellaneous agencies, and even the Department of Defense now comes in third of fourth (it is grouped with the Department of Veteran Affairs and the State Department to show it as a bigger piece of the federal budget in the 2001 tax booklet from the IRS).
I'm not advocating a renewal of NASA funding to 1960's funding levels (which was about 10% of the Federal Budget), but I am suggesting that it certainly is no longer a national priority, as defined by the United States Congress and the President of the United States.
Unfortunately, with much of the space infrastructure in Texas and strong Republican states (like Alabama, Utah, or swing states like Florida and California), I highly doubt that it could be cut with the current administration either.
{Rant Mode Off}
Nuclear efficiency is in between. While there is not complete conversion, there is some mass going to energy, unlike in chemical rockets. However, nuclear physics is practical and well understood. A system would probably not work just as a bunch of bombs going off(though research was done on that, see The Binding Curve of Energy), instead liquid fuel, possibly liquid hydrogen or ammonia, would be sent through a nuclear core, then expelled. This would allow radiation release to be kept in check pretty easily, and a highly efficient super-heated plasma would propel the ship. In addition, unlike normal rockets the plasma could be controlled with magnetic fields.
While nuclear certainly holds a great stigma to many people, and is not as sexy as advanced antimatter/space warp/whatever systems, it is here and could be turned into a drive with minimal fuss. I could see a single nation/group(of sufficient economic strength, aka US, EU, possibly Japan) or coalition of nations getting behind this and making a ship to do it. The others will be needed, and research should continue, but if we want to go to other planets in the next couple of decades, this is probably the technology to do it with.
Every known matter particle has an antiparticle which has identical mass, but opposite charges (for every kind of charge, including electrical). We don't know why, they just do. There doesn't seem to be much antimatter out there; again, for reasons unknown.
Antiparticles still have positive mass, like every other known particle, and are not repelled by gravity.
When a particle meets its antiparticle, they are converted into their combined mass worth of energy in accord with: E=mc^2 (where E is the energy, m is the combined mass, and c^2 is a ludicrously large number). Hence, antimatter is the most compact form of energy storage theoretically possible.
In other words, pretty good rocket fuel. Antimatter bombs would be rather unpleasant, and any contained antimatter is a potential bomb (there's nothing "potential" about uncontained antimatter for very long).
There is no reliable, efficient way of making antimatter, and no place to just pick it up for free. However, if you smash protons together hard enough with huge particle accelerators, they occasionally spit out highly energetic photons that decay into matched matter/antimatter particle pairs. With luck, you can catch a few in a magnetic field and hold them for a little while. This is about as cost-effective as it sounds.
If you ever meet your anti-self, and he hasn't exploded yet, either he or you will before you have a chance to shake his hand, so don't worry about it.
Despite this title, and the potential benefits of effective antimatter storage, antimatter can not be contained by a nutshell. Don't try.
Of the amount of energy created by matter/animatter annialation, consider the amount of energy that goes into creating the antimatter in the first place. The size of the accellerators and all the energy it takes to operate, just to produce a single particle of antimatter.
What you get out of this, is the energy potential equivalent of accellerating a single particle to near the speed of light. Thats a LOT of energy and it can be stored within two particles. Its no wonder that we need a very small amount of it to accomplish great things.
However, its extremely costly and time consuming to create, and without drastically improving the effiency of the creation process, this is not going to change anytime in the near future.
Also, don't forget about the potential arms race here. Antimatter doesn't occur naturally in nature like nuclear elements (such as uranium) do (at least not in a form that can be collected easily). Right now nobody has the capability of creating enough antimatter to do any significant damage. But if we are able to create enough to be useful, a few grams of antimatter could be used to make a weapon that is significantly more powerful than a nuclear weapon. And although tactical nukes come in briefcases, imagine a bomb of equal power that fits inside a watch.
Another issue to consider is that antimatter needs to be stored. If a chemical fuel tank leaks, no big deal. If a nuclear fuel tank leaks, you might get radiation poisoning, but the effect will be limited. If a gram of antimatter gets loose. WATCH OUT.
Still, if we plan to travel great distances, its a necessary step.
-Restil
Play with my webcams and lights here
Is antimatter really being used for medical imaging?
Absolutely. Positron Emission Tomography (a positron is an anti-electron)
Hogsback
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
You could probably engineer something like a constant inflow of anti-matter to make for continous thrust. The only problem is the back flow on the fuel lines. this would be a lot easier than having a continous atomic fission explosion for thrust.
Strangely enough, this also works as a method fo moving asteroids around, since you could have atomic fuel lines running to a convenient crater. A trickle feed would create a continous nuclear reaction that would push the asteroid to a new course.
Alot of this stuff would need to be NOT engineered in low earth orbit, for obvious reasons.
"It is a greater offense to steal men's labor, than their clothes"
The problem that's not addressed in the article is that sure, antimatter is small, light, and excellent for storing energy with little mass, but what does that energy get you? Every spacecraft we've ever designed uses a reaction drive (and yes, solar sails are reaction drives too. They just use external sources as propellant.). The article doesn't address how we tackle the problem that for reaction drives to work we need to have something to throw behind us at high speed.
Not to say NASA isn't working on it. I'm sure they're looking at Bussard Ramjets or some other mechanism for using this tremendous energy to snare interstellar particles and throw them behind the ship. In fact, NASA has a few projects on the books for exploring exactly where the barriers between stellar and interstellar wind lay, and what the particle densities are really like. I guess this sort of detail is just too much for the average CNN reader.
The article, as is, doesn't provide any reason for being written now, other than a 'gee whiz the future's out there' fluff piece.
Hey, at least it's not about Afghanistan or weapons development.
Kevin Fox
Robert L. Forward covers the topic of antimatter and some of its uses in his book Indistinguishable From Magic. You can find some information online about him and get some links to his ideas at his website.
Sapere aude!
Star Fleet entrance exams may say this is a "trick question," but you really don't want to use a 1:1 matter/antimatter mixture.
The core issue is that energy, per se, is irrelevant in spacecraft propulsion. What matters is momentum transfer.
Kinetic energy scales as mv^2/2. Momentum scales as mv. So the "ideal" system would make a lot of mass move slowly... but that would require you carry around a lot of mass so you can throw it overboard.
Matter/antimatter is on the other extreme. Lots of energy, very little momentum transfer. If it were a sports car, the driver would be spinning his wheels and burning rubber, but barely moving because the tires aren't gripping the road.
I vaguely recall ideal matter/antimatter ratios being something like 10:1 to 20:1. If you assume the amount of junk thrown out goes up by a factor of 16 or so, the velocity will drop by a factor of 4. However the momentum transfer will be bumped by a factor of 4. You have to carry more reaction mass, but if you're talking about a less than an ounce of antimatter, a 16:1 ratio means a whopping pound of reaction mass.
A more advanced version of this gives you variable thrust engines. If you're in a deep gravity well, you toss in more mass so you burn more consumables but have better momentum transfer where it's critical. When you're in deep space, you use less reaction mass for the same amount of fuel.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
Surprisingly enough, no, this is not a problem.
Let's make a few assumptions:
The distance to Mars would be 55*10^6 km = 55*10^9 m.
We use a 1 g accelleration all the way. That's the same as on earth. We turn the ship when we're halfway there and start braking with 1 g, so we can actually stop and do some sightseeing on Mars.
Now, assuming we start with a velocity of zero, the equation relating distance and accelleration is:
s(t) = 0.5*a*(t^2),
Where s = the distance in meters, t is time in seconds, and a is accelleration in m/s^2.
One g is approximately 10 m/s^2. s(t) is our halfway distance, or ~ 27.5*10^9 m. Substituting all that results in:
t^2 = 55*10^8, so t ~ 74000 seconds ~ 20.5 hours. That's for the trip halfway, so the total travel time would be around 41 hours = less than 2 days!
The top speed would be an impressive 740 km/s, which is high, but not nearly high enough to get in trouble with Einstein's relativity laws.
So, a few weeks doesn't seem that unreasonable. It's more the anti-matter thing that seems to be the problem.
Btw., let me know if I miscalculated anything....
MSN 8: Now Microsoft even has bugs in their ad campaigns.
What about the theoretical exotic matter?
Antimatter is matter with a reversed charged.
When matter meets antimatter, both are annihilated and energy is released (a lot of it, based on E=mc^2).
Exotic matter, which isn't generally considered possible under Newtonian physics but which might be possible under quantumn physics, is matter that has a negative mass, and negative energy density. It has the opposite gravitational effect in relation to normal matter. A body of exotic matter would repel other bodies of both exotic and normal matter, AFAIK. Exotic matter, if it could really exist, would probably spread out equally across space, since it repels, rather than attracts other matter. If it came in contact with normal matter, it would annihilate it, but, unlike antimatter, it would release no energy whatsoever.
In general, the idea of exotic matter is very appealing, because it allows:
1.) The stabilisation of Einstein-Rosen gates, allowing an effective portal to another universe, should one exist. An Einstein-Rosen gate can be created by a spinning black hole, but is extremely unstable, to a point where even a boson would cause it's collapse.
2.) Construction of wormholes. (You need a great deal of exotic matter for this one, probably more than is practically attainable, even with very advanced technology)
One design suggests a wormhole that creates it's own exotic matter, eliminating the need for it's production.
3.) Construction of 'warp drives'. Alcuberre's warp drive (do a search on Google if you want to know what that is) violates certain conditions of quantumn physics and required an absurdly large quantity of energy. However, Chris van den Broeck, suggested an alteration of the design, whereby the 'warp bubble' would be extremely small (smaller than a proton) and the starship/object to be warped would be in another bubble which a larger internal volume than it's external volume. In principle possible, perhaps, but it's not known if the idea would work in reality, especially since the author of the paper has since published another paper listing problems with his proposal.
Still, the idea is kind of interesting.
Nobody knows if exotic matter is possible at all, let alone whether it's mass production is feasible.
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
Science, like Nature, must also be tamed, with a view turned towards its preservation.