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Space Science

NASA Researching Antimatter Engines 385

Posted by michael from the improbability-drive-coming-soon dept.
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."
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NASA Researching Antimatter Engines More

NASA Researching Antimatter Engines

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  • There Something Wrong With This picture! (Score:5, Funny)

    by msolnik ( 536110 ) on Saturday January 12, 2002 @11:52PM (#2831123)
    There is something definately wrong with the picture on cnn.com. This picture [cnn.com] looks very wrong someone must have been thinking bad thoughts at the time.

  • How to contain it? (Score:3, Interesting)

    by Mnemia ( 218659 ) on Saturday January 12, 2002 @11:56PM (#2831146)
    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?

  • From nasa (Score:5, Informative)

    by hogsback ( 548721 ) on Saturday January 12, 2002 @11:56PM (#2831152) Homepage
    There's an older (1999) article [nasa.gov] on nasa's site with a bit more technical detail.
    • for instance ...

      Is antimatter really being used for medical imaging? Considering the trouble it is to make, it seems like antimatter wouldn't be cost effective for this kind of use, and would be overkill for the cancer treatment proposed in this article. I could use a reference link here if anyone knows of one.

      I can see the advantage in propulsion since so much of the weight of our current rockets is fuel, and most of that fuel is spent lifting other fuel.

      However, if we have to create our own antimatter from scratch, the amount of fuel needed to travel to the nearest star (a common goal for which anti-matter is often considered a solution) would probably overtax our planet's energy resources. (This is presuming we don't just find a huge supply of antimatter hiding behind Saturn or something -- which isn't likely from what we think we know about the universe.)

      So antimatter, like wormholes, would probably become just a plaything for the rich. I predict it will be used for the ultimate in opulent jewelry.

      • Is antimatter really being used for medical imaging?

        Absolutely. Positron Emission Tomography [biomed.org] (a positron is an anti-electron)
        • From that page:
          Through surgical removal of this area of the brain, the patient is rendered "seizure-free".

          Yikes! =)
        • I think we have to distinguish between antiparticles and antimatter, just as we distinguish between particles and matter.

          As I write this, an electron gun [techtarget.com] is spewing streams of electrons directly at my face. Yet I don't feel the slightest urge to duck. Nor do I hear little clicking sounds as the electrons impact on my monitor screen. I don't expect any of the things that happen when matter is about, because electrons aren't matter. They're a constituent of matter.

          The anti-electrons used in PET scans are the same, only more so. Nothing remarkable about having them around [optusnet.com.au], but they're extremely transient entities. So accumulating them in large quantities is a lot harder than this article, in the gee-wiz style NASA PR bozos are so fond of, suggests.

          • ...distinguish between particles and matter...
            As far as I know, this is not the case. Given your statement, hydrogen ions (say, in a plasma) would not be matter because they would be naked protons. I don't think anyone would agree with this.

            Yet I don't feel the slightest urge to duck. Nor do I hear little clicking sounds as the electrons impact on my monitor screen.
            Well, of course you don't. Electrons are smaller than visible light wavelengths, so you can't see them--hence scanning electron tunneling microscopes. You also don't hear the occasional proton or neutron that races down from the heavens and through your body, but that doesn't mean anything either. The total energy of these particles is too small to cause the gross physical movement that we would perceive as sound.

            I have never understood there to be a quantitative distinction between particles and matter. I can certainly see a qualitative distinction--we are used to defining "matter" as the stuff we directly interact with day to day.

            But, barring a more formal definition (the existence of which I admit I am ignorant), it seems that "matter" is adequately defined as an entity with rest mass, and electrons have rest mass, albeit small. Admittedly, it's not intuitive to think of the current from the battery running my laptop as "matter", or as a "matter" flow, but this doesn't dissuade me from using that definition.

  • Yes, but ... (Score:5, Funny)

    by J.D. Hogg ( 545364 ) on Sunday January 13, 2002 @12:03AM (#2831179) Homepage
    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 ?

  • It's not as cool as it sounds (Score:3, Interesting)

    by anonymous loser ( 58627 ) on Sunday January 13, 2002 @12:08AM (#2831195)
    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.
    • Yeah, well.. When I write code I assume there will be a database that meats spec, an interface that meats spec, a server that meats spec, etc. I write the libs to my spec which is compatible with everything else.

      If I were to do it all (including building the transistors on the chips through installing the OS through everything else) it would take me a couple of lifetimes.

      It's called building a component. Sure it's a little easier when you have the actuals to work with, but thats why you make test jigs and other stuff to try out what you've done without relying on anything else.
      • lol.. Sorry about all the misuse of meat.

        Cooking steak for lunch and I guess I must be more hungry than I thought.
      • That is true, but I don't think you quite get my point, which is that there really isn't anyone at NASA actively developing an engine according to the "specifications" they are using.

        Basically they just say "hmm...let's just assume it weighs X, delivers power Y, and has lifetime Z" and see what vehicle design is possible.

        The folks I talked to basically flat-out said they (NASA) don't do much research into that kind of stuff, and they mostly leave it up to the universities and private industry to come up with the technology. Of course, NASA does shell out mucho $$$ every year to fund research, but they don't participate directly.

        If you're interested in what kind of research NASA and other government agencies are funding, you can head over to FirstGov [firstgov.gov] and do a search on SBIR [firstgov.gov]. That doesn't cover ALL of the research or development projects, but there are plenty of cool ones in there (stuff like using mech-like tech to enhance human capabilities).

  • Gene Roddenberry (Score:3, Interesting)

    by Sivar ( 316343 ) <charlesnburns[@]gmail . c om> on Sunday January 13, 2002 @12:09AM (#2831199)
    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?

    • Re:Gene Roddenberry (Score:2, Funny)

      by Anonymous Coward

      > Was this guy good or what?

      What.

      Aliens = humans with lumps of rubber glued to their heads. (More recently evolved species sometimes have patterns of tatooing as well.)

      Spaceship = flying palace with hallways wide enough to make the owners of a luxury liner jealous, but no spares for parts on critical pathways. Also, lots of ways for enemies to take over some vital system and lock out access by the crew, rather than vice versa.

      Tactical Doctrine = if the air is breathable then send down the captain, the first officer, the science officer, the ship's doctor, a helmsman, the security chief, and one expendable crewman, to see what destroyed the colony and left no survivors.

      Plot = an intelligent * takes over the * because it wants *, and the crew would have all *ed if * hadn't figured out that * would make it go away without killing anyone.

    • Cell phones = communicators

      Try walkie-talkies. I used to play with them back when the original series was on.

      Babelfish = universal translator

      Which, I think, must show that you have never actually tried to use Babelfish to translate a web page.

      Taser(tm) = Phaser on stun

      Very true, except that it isn't that at all. It's not a ray gun, it has a short range, and it often doesn't work.

      2-way videophone = Screen on the bridge

      Two-way videophone prototypes were being built back in the 1960's. We had one in our science museum in Columbus, Ohio.

      PC = Enterprise computer terminal

      Computers in Star Trek have always been comtemporary with the computer technology at the time of production. In the 1960's, they were room-sized or refrigerator-sized. Later they became portable, achieving a laptop form factor during TNG, and a palm form factor in the 1990's. There's no prediction there at all.

      Now antimatter propulsion.

      Now, not. NASA is not saying this could come on line in less than about a century, and nobody is talking about using it for space warps. Yeah, it may be useful for jetting around the solar system in 2100, maybe even an unmanned long-haul star probe or two around 2150 or so, or maybe not, but it's nothing at all like warp drive.

      Was this guy good or what?

      Not.

      Tim

  • Cost (in energy) to produce (Score:3, Insightful)

    by jdavidb ( 449077 ) on Sunday January 13, 2002 @12:11AM (#2831206) Homepage Journal

    Am I the only one thinking antimatter costs more energy to produce than you get out of it?

    • Re:Cost (in energy) to produce (Score:5, Informative)

      by RevRigel ( 90335 ) on Sunday January 13, 2002 @12:23AM (#2831231)
      You don't understand thermodynamics. Of course it takes more energy to produce than we get out of it. 2nd law of thermo. For spacecraft, small and light is better. Antimatter, per joule, is the smallest and lightest allowable by the laws of physics as we currently understand them.
      The idea is that we can use wind power, solar power, or crude oil generated power to make the antimatter here on Earth, and then take antimatter into space with us. None of those other types of power exist in space (except solar, which doesn't exist for any practical purposes if you start using antimatter propulsion to go to other stars..which is entirely possible when you have an exhaust velocity equal to the speed of light..well, almost, since matter and antimatter produce neutral and charged pi-mesons when they annihilate. the neutral pi-mesons decay into gamma rays that spray in random directions very quickly, but the charged pi mesons don't. so the idea is to shape the exhaust flow by moving the charged pi mesons when an electrostatic or electromagnetic field before they decay).

      You're a victim of the same mistaken thinking that the comments about the hydrogen power generation story a few days ago were saturated with.
      • 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.
    • I'd rather only have to pack a kilogram of antimatter on my space ship than a moderately sized inland sea's worth of chemical fuel.

    • Am I the only one thinking antimatter costs more energy to produce than you get out of it?

      It's not about cost to produce. It's about how much usable energy you get per pound of fuel that you have to carry with you. It's worth it to spend the energy up front in order to make the trip through space feasable.
    • The clue here is efficency. Here on earth energy exists in massive amounts compared to in space, the problem is bringing it up there.

      Lets say anti-matter has a 1:10 efficency (with engines and all, just as an example). Say you want to send 1 ton of payload into space. This takes 100kg of fuel. But in order to make room for those 100kg, and fuel to put that up there, you need another 10kg. And to put those up there you need even more room and fuel, say 1kg and so on, a total of 1111,11... kg. Only 1/9th of the payload.

      Now take a conventional rocket at 9:10 efficency, still 1 ton payload. But now you need 900kg fuel to get it up there. And to make room and bring fuel for those 900kg fuel you need another 810kg. To make room and bring fuel for those 810kg you need 729kg more and so on. In total, you need to send up a rocket weighing in at 10 tons, 90% of which is fuel, fuel tanks, engines and other costly but not value-adding components. All together it's 9 times the payload.

      So a 9:1 improvement in efficency is a 81:1 improvement in size of the non-valueadding parts. Parts of it will be fuel, part fuel tanks, part engines, none of which are cheap and that all take a lot of energy to produce and use.

      Kjella

  • antimatter versus antiatoms; containment (Score:5, Interesting)

    by bcrowell ( 177657 ) on Sunday January 13, 2002 @12:17AM (#2831218) Homepage
    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.

    • The article doesn't distinguish between antimatter and antiatoms.

      You're right. An older NASA article [nasa.gov] mentioned by an early poster (above) gives more details. Basically they are talking about using antiprotons as rocket fuel. These are stored in a fairly gargantuan Penning trap (active volume one millimeter in size... well these things are relative, don't you know!).

      Antiatoms are discussed in the article as well; easier to store but much, much harder to make than plain old antiprotons.

      You have to have an extremely good vacuum, however

      When you're dealing with antimatter of any sort you have to have a very good vacuum regardless. Happily, this is not very hard, we can make the best vacuums in the known universe right here on Earth, much less in space...

      -Renard

      • From the article you referred to:
        • A trillion antiprotons is the maximum that can be stored under those conditions. More could be held if they were turned into anti-hydrogen, anti-protons plus positrons.
        A trillion antiprotons is about 10^12 GeV=10^21 eV=100 J, which is less than the calories in a bowl of cheeries.
  • I would be rich... (this abused phrase notwithstanding).

    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 /. readers) would consider archaic. I mean, 16 bit processors are finally being used for many missions and 8 bit processors are still common.

    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}
    • I mean, 16 bit processors are finally being used for many missions and 8 bit processors are still common.

      It's very costly to mathematically prove that a program has zero errors (which is presumably what NASA does -- the data they input is another story). Once you've proven a given program works perfectly, there's no reason to "upgrade" it. Besides, most things would be simple physics calculations (trajectories, fuel consumption, etc), which don't change very much over time, so, again, there would be no need to re-invent the wheel.

    • I mean, 16 bit processors are finally being used for many missions and 8 bit processors are still common.

      Yes, but a) they are cheap, b) they are known to be reliable, and c) they are plentiful and easy to get radiation hardened versions of.

      Most embedded processors don't need to be more complex than that... it just adds unneeded complexity.
    • ...and even the robotic probe missions are using what most geeks (and /. readers) would consider archaic. I mean, 16 bit processors are finally being used for many missions and 8 bit processors are still common.
      You don't want 256 bit, billion gate gamma-ray lithographied GaAs processors in space.

      You'd rather have something reliable whose traces will not be overwhelmed by particle bombardment in Space.

      That's why NASA uses prehistoric microprocessors (when it uses any).

      And commercial Clarke-Orbit communication satellite are even more "primitive": no microprocessors at all. Just discrete wired logic.

      Because it's a fucking long way to press the "reset" button if the processor hangs...

    • Sorry, you're just wrong. (Score:4, Interesting)

      by RobertFisher ( 21116 ) on Sunday January 13, 2002 @06:44PM (#2834054) Journal
      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 [nasa.gov]
      [nasa.gov]
      Hubble Space Telescope
      Earth Observatories
      Advanced Spaceborne Thermal Emission and Reflection Radiometer" [nasa.gov]
      Solar System Missions
      Mars Rovers [nasa.gov]
      Astrophysics Research
      Origins Program [nasa.gov]
      And a sampling of the slate for future missions :

      The Terrestrial Planet Finder [nasa.gov]

      Deep Impact Comet Mission [nasa.gov]

      Dawn Asteroid Flyby" [nasa.gov]

      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

  • A nuclear engine seems more practical for now (Score:5, Insightful)

    by Zergwyn ( 514693 ) on Sunday January 13, 2002 @12:20AM (#2831226)
    When evaluating the usefulness of a potential fuel, one of the most important things is how efficiently that fuel can be converted to energy, and in engines the heat differential between the coldest and hottest parts of the system. Matter-Antimatter is very efficient, as there is direct mass->energy conversion. Combustion is very inefficient(a lot of burned fuel, not much energy).

    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.

    • Nuclear efficiency is in between. While there is not complete conversion, there is some mass going to energy, unlike in chemical rockets.

      Err, no, that is wrong. Chemical reactions transform mass into energy just as nuclear reactions do. It's just that chemical reactions transform a far smaller percentage of mass into energy. So, as you correctly point out, it's an efficiency thing. The reason is that chemical reactions work on the binding energy between electrons, whereas nuclear reactions act on the
      atom's nucleus, where energies are magnitudes higher.

      It's all rather confusing, since the number and type of particles are the same before and after the reactions, both for chemical and nuclear reactions. However, the assembly of particles have different masses before and after reactions. So where did the mass that was converted come from? Well, just as mass is equivalent to energy, so is energy equivalent to mass. The binding energy in atoms is mass, obeying E=mc^2. And that is the energy/mass that is freed during a reaction, be it a chemical or nuclear reaction.

      Hope that didn't confuse things any further...

  • Antimatter in a nutshell: (Score:3, Insightful)

    by Nindalf ( 526257 ) on Sunday January 13, 2002 @12:27AM (#2831239)
    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.

  • To get an idea.... (Score:3, Interesting)

    by Restil ( 31903 ) on Sunday January 13, 2002 @12:29AM (#2831250) Homepage
    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

  • Devil is in the details (Score:4, Interesting)

    by StefanJ ( 88986 ) on Sunday January 13, 2002 @12:36AM (#2831276) Homepage Journal
    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

  • Energy is only part of the problem. (Score:3, Insightful)

    by KFury ( 19522 ) on Sunday January 13, 2002 @12:50AM (#2831315) Homepage
    The article, as written, is pretty shoddy, and looks similar to articles written 70 years ago touting how everyone would eat pills for food and fly personal jetpacks.

    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.

  • ... it gives a whole new meaning to the term "vaporware."

  • A good place for info... (Score:3, Informative)

    by Graff ( 532189 ) on Sunday January 13, 2002 @12:58AM (#2831328)

    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 [robertlforward.com].

  • Just(!) a gram of antimatter required to get to Mars? Anti-neutron and "corresponding anti particle for all particles"? With a gram of antimatter I can get you to Alpha, fire those Nasa engineers who can only get you to Mars and hire me. But don't give me a gram of those anti-neutrons, I can't even get you to grocery store with those.

    I wonder what cnn reporters smoke.

  • Antimatter is the most efficient energy storage possible. 'E = mc^2' tells us that annihalating it with an equal mass of matter produces 9*10e16 joules of energy for every kilogram of mass thus reacted.

    That's the instantaneous production of 90,000 terajoules - on the order of the amount of energy expended by all the world's industry in a day. Impressive? Certainly.

    However... to accelerate a mass to the near-light speed necessary to take advantage or relativity (very useful in an interstellar voyage if you want to get there in a reasonable fraction of a human lifetime), you need... E = mc^2!

    That means that to get to near-light speed with a 100%-efficient antimatter engine, you need to have almost as much matter/antimatter fuel as the 'dry weight' of the vessel, including storage tanks. The dry weight of the Space Shuttle orbiter is about 80 tons... so to get a shuttle to those kinds of speeds would take 40 tons of antimatter and 40 tons of ordinary matter.

    AND... you have to slow down again at the other end. So you have to take the 160 tons of your decel mass, and get THAT up to light speed with another 160 tons of fuel (again, half matter, half antimatter). So the launch breakdown on your itty bitty 80-ton eight-person spacecraft is: 80 tons spacecraft, 120 tons matter, 120 tons antimatter - 320 tons!

    It's just like rockets and gravity. Most of your launch mass is wasted on fuel. And we can't beat these numbers with our current physics.

    None of this would be a problem if we could make a LOT of antimatter... like a ton a day. But that has its own problems. Like, where to put it.

    Let's assume that breakthroughs in nanotech and fusion physics allow us to build reactors that are one millimeter across and turn hydrogen into antiprotons at the rate of 1 particle per microsecond. To produce just 120 tons of antimatter per year, the factory would form a cube 200 meters on a side (Borg, Anybody?). I don't know what such a thing would be made of, but an equivalent volume of water would weigh 8 million tons.

    The 4H2 -> He2 fusion reaction releases approximately 1/140th the mass-energy of the original hydrogen as a side-affect of the fusion reaction (go ahead, look up the relative masses of H and He on your periodic table and plug it into E = MC^2, you'll see what I mean). That means that a 100% efficient 'factory' would burn 140 times the mass of hydrogen to produce one unit of antimatter... or 16,800 tons of hydrogen per year.

    So is it impossible?

    No.

    IF we had the fusion physics and the nanotech, we could put a self-assembling factory into orbit in the upper atmosphere of a gas giant. Feed it a large iron asteroid for raw materials, and allow it to grow slowly, adding a 1mm layer of fuel reactors at a time. The size of the thing would grow at cubic rates (since it grows in three dimensions) and even though the initial fuel output of the thing would be trivial, it would quickly grow to a size where it was producing tons of fuel a year.

    And THEN we can start sending people to the stars on a regular basis. First a dozen, then hundreds, then thousands, at a rate that grows as fast as we can produce the fuel.

    Like JFK said... We choose to do these things 'not because they are easy, but because they are hard.'
  • When a matter particle comes into contact with an antimatter particle, they annihilate each other and produce kinetic energy.

    Actually no. Kinetic energy is an abstraction related to momentum. When matter and anti-matter collide they produce photons, gamma particles, according to the formula E=MC^2.

    But because no one knows where to find the antimatter, it has to be created.

    It's not that it's lost and nobody knows where to find it. Anti-matter is pretty uncommon, at least in our pocket of the Universe. Anti-matter in tiny quantities is always being produced by nuclear decay, but since it's surrounded by regular matter, it annihilates very quickly producing gamma rays.

    I know it's CNN, but c'mon -- if you're doing a piece on antimatter, at least have a scientist look it over before you publish it.

  • NASA has also revealed that it is researching ways to use magic as the next generation spacecraft propulsion. One scientist was quoted as saying: "With magic we could, for example, twitch our noses and *wish* the spacecraft to be at it's destination" "However," he cautioned, "magic is not known to exist. Nor may it ever". NASA has reportedly employed a young new scientist by the name of Harry Potter to aid in its newest research project.
  • from the article:

    The world's largest maker of antimatter...

    I never thought I'd read this sentence in my lifetime!

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