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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.
yes you can.
.... bang!
Anti-protons (say) are just as real as protons and weigh the same. It's just that you have to be really careful because if an anti-proton meets a proton
Hogsback
im pretty sure it means measure of mass since the wieght depends on the gravity. And antimatter has mass.
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
I'm assuming (and only that) that 1g of antimatter would be inversely identical (?!) to 1g of matter.
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
Yes, but you need to be careful to only weigh it with scale made of antimatter. Or at least indifferentmatter.
Error: PANTS NOT FOUND. Press <F1> to continue.
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 ?
All the more reason to get our asses into space, so we can set up automated plants to manufacture anti-matter far away from inhabited areas...
Besides, free power (solar), free reaction mass (with sufficient heat, we can liberate volitiles from moon rock, asteroids, etc), and we're already outside of the gravity well... lots of advantages to doing space-related research, while actually in space. We just have to make like we want to stay there, instead of making very expensive vists all the time.
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
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.
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.
That's the least of your worries. Live anywhere near a gas storage facility? Toxic dump? Or even a gas filling station? How about within several states of a nuclear power facility?
The slightest thing going wrong with the containment at any of these places and you can kiss your ass goodbye.
Now we all know that these things don't blow up every day but - broadly speaking, scientists in a lab type environment take far more sensible precautions over the storage, use and containment of potentially hazardous materials than people in the real world.
That's because the scientist's priority will invariably be safe, repeatable research carried out in baby steps whereas the real world corporations will always weigh risk against profit.
And, personally speaking, I don't think that a bean counter focused on the fiscal bottom line is the best person to trust when it comes to safety.
"Accept that some days you are the pigeon, and some days you are the statue." - David Brent, Wernham Hogg
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
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
I don't know if you can weigh antimatter in the traditional sense, but since mass is proportional to the amount of force required to accelerate a body a given amount (or something like that), I would say that if you can move antimatter, you can figure out its mass.
Yes, magnetic fields. Anti-matter is affected by magnetism. You just need to make sure that your storage chamber has a very hard vacuum, unless you want a stray dust molecule running into a bit of antimatter.
Vote monkeys into Congress. They are cheaper and more trustworthy.
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.
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"
Actually, only some of it is crap.
That thing about the "crystalline structures" thing is how I would say dilithium crystals work (from Star Trek), if they actually did work. Totally my theory.
As far as the warp theory idea, its a natural (and probable) consequence of the theory of curved space. Its all dependant upon the what-if: "What if I could spontaneously create and destroy massive amounts of matter at will?"
And the last bit was from the movie "First Contact."
Mod me down and I will become more powerful than you can possibly imagine!
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
... it gives a whole new meaning to the term "vaporware."
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!
There's other types of nuclear propulsion systems, but this is the simplest.
I'm wondering what the 'Anything Nuclear = Bad' crowd would think about antimatter. Too deep for them to comprehend, much less complain about?
Dyolf Knip
Backflushing the bussard collectors messed up your phase discriminator calibration? Reverse the polarity! Pattern buffer's isolinear chips not working with the biomatter resequencer? Reverse the polarity! Isomagnetic disintegrator fried the power transfer conduit to the main deflector, making it impossible to reroute warp power to the tractor beam emitters? Reverse the polarity!
But if your self-sealing stem bolts break, you're completely screwed.
Bugrit! Millenium hand and shrimp!
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.
Or were you thinking it was like Ghostbusters where they were about as big as a backpack?
Who did what now?
On the contrary, the gamma-rays (even when they are not energetic enough to cause fission) will merely be absorbed by the high-Z nuclei, knocking them loose to rattle around the spacecraft (kinetic energy), or alternatively raising them to an excited state, after which they will relax by emission of one or several gamma-rays in random directions (isotropic distribution). Since you will have absorbed the momentum of a gamma-ray that was going in the wrong direction, you will end up with a net loss.
If it were that easy to "reflect" gamma-rays, believe me, gamma-ray astronomers would have been doing it a long time ago...
-Renard
No, I do know how big a typical particle accelerator is. I was personally thinking a cyclotron would be better. They don't have to be 1 mile in diameter, they just use that for really energetic stuff. To produce antimatter AFIAK you only need a cyclotron around 50 metres in diameter. IIRC some universities have small units for this purpose.
I'm unaware of any principle of physics which says that mass must always be positive. Look at either Newton's or Einstein's laws of motion, for instance--in F=ma, you can plug in negative numbers for mass just as easily as positive numbers. You get answers which are self-consistent (if sometimes counterintuitive) and which maintain the beauty of the mathematical system. These are tantalizing hints--and that's all they are, hints--that negative mass is permitted by the universe.
:)
We have no idea how to make it, but we know what it would look like, how it would interact with positive mass, and how forces would act upon it.
I was personally thinking a cyclotron would be better. They don't have to be 1 mile in diameter, they just use that for really energetic stuff. To produce antimatter AFIAK you only need a cyclotron around 50 metres in diameter.
The thing about a cyclotron is that it's a solid device (magnets, vacuum chamber, etc) so one that's "only" 50 metres in diameter would still be a helluva lot of material to haul around. TRIUMF's magnet is 18m in diameter, and it's the world's largest.
You also have to specify what type of antimatter you want to create. TRIUMF has a beam energy of about 500 MeV, so it cannot create antiprotons (which have a mass of 938 MeV, but which according to this page need 6 times that much energy to satisfy the necessary conservation laws when creating them). However TRIUMF has no problem creating positive muons or positrons (which still qualify as "antimatter").
A local company, Ebco Technologies, sells small cyclotrons for the production of medical PET radioisotopes. These aren't quite backpack sized, but they would easily fit into an apartment (provided the floor was strong enough and you had 80kW of electrical power available).
If you make anti-hydrogen you are able to store it in normal gas storage cyclinders.
No, you are not able to store anti-hydrogen in a (normal matter) gas storage cylinder. Kaboom, unless you have some way to prevent it from coming in contact with the cylinder walls (and electromagnetic fields won't work well on neutral atoms).
Same goes for any anti-atom. anti-matter only annihilate's when if touch's its couterpart. Simply(in theory) keep them apart.
Are you under the impression that an anti-hydrogen atom will annihilate with an atom of normal hydrogen, but not (e.g.) a normal iron atom? If so this is wrong; the annihilation takes place at the level of individual electrons and protons.
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
Live today, because you never know what tomorrow brings
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
Wouldn't it be possible to make it go around the main loop several thousand times before going out? I'd imagine a beam of antiprotons would be needed to do anything useful. It's gunna take a heck of a lot of power though.
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.
The law of conservation of matter has been merged with the law of conservation of energy, and the two are now the law of conservation of matter-energy. All Einstein's fault. It's the famous E=mc^2 equation, that tells us that the conversion ratio between matter and energy equals c^2 [m^2/s^2]. That's a rather high number (~ 9*10^16 m^2/s^2), so we don't really notice the disappearing matter in real life. In other words, yes, matter is annihilated (destroyed), but we rarely notice. Note that this does not just apply to matter/anti-matter reactions, "ordinary" nuclear and chemical reactions obey the same law.
It has been demonstated in lab experiments that the opposite also holds. Given the right conditions and the right amount of energy, you can actually make particle/anti-particle pairs pop up out of nowhere!
MSN 8: Now Microsoft even has bugs in their ad campaigns.
So how do you keep the protons and the anti-protons from meeting?
You had me at "dicks fuck assholes".
I wonder what cnn reporters smoke.
Gentlemen, you can't fight in here, this is the War Room!
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.
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.'
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.
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.
As I write this, an electron gun 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, 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.
Wouldn't it be possible to make it go around the main loop several thousand times before going out?
It already does that. The way a cyclotron works is that charged particles in a magnetic field move in circles. It turns out that the radius of the circle increases as the particle's energy increases, but the time for one period remains constant. A cyclotron injects charged particles near the center, and they start moving in circles. Every time they cross the mid-line of the device, an AC field gives them an energy boost and moves them to a slightly greater radius (the field reverses polarity every half-orbit, so the field is always pushing the particles along their direction of travel). When the particles have gained enough energy to reach the outer edge of the device, they are extracted and sent down the beamline.
Cyclotrons are good at producing a very high number of particles per second (so they're great for isotope production), but they don't easily scale to the energy levels needed to create antiprotons.
howstuffworks.com has a bit more information.
Physicist Robert L Forward wrote a popular science style book, Indistinguishable From Magic. The first chapter is titled Antimatter, discussed what antimatter is, how we storeit, produce it, how we could produce it econmonically, how to use it more space travel and more mundance applictions.
He also wrote a book specifically on antimatter, which he renamed "Mirror Matter." It's an utterly ridiculous book that has us all jetting to the moon for weekend vacations in our antimatter-fueled cars by 2005. Yes, that's right, three years from now. Mind you, the book was not science fiction -- it purported to be hard-headed prediction. Among other fascinating revelations: There is actually no possibility of dangerous radiation from antimatter propulsion, because it would only produce harmless pions. (And what do the pions turn into, Bob?) We could reach the nearest star in only forty years with a few hundred kilograms of antimatter, but even though one gram of antimatter is equivalent to a Hiroshima bomb, we don't need to worry about weapons proliferation, because while it could obviously be economically feasible to produce antimatter by the kilogram, it never could be feasible to produce it by the gram! Etc., etc. The sheer idiocy of the book is staggering, and only more so because it seems as if the writer must have known better.
Tim
The key advantage is that it allows problems to be fixed a lot easier.
Yes but you use the antimatter beam to destroy their ship. The shields would be impractical to protect the entire earth, they only protect the ship.... :-P
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.
It was also used in the drop tests. The very first flights were on top of the 747 to test basic aerodynamics, later tests used explosive bolts to separate from the 747 and simulate the final stages of reentry.
Remember - up until this time every spacecraft went "splat" when it landed. Americans landed in the water, Soviets landed in farm land... and according to the standards boards Yuri Gagarin was *not* the first man to pilot a spacecraft in orbit since he bailed before the capsule even got back to earth. (The standards require the pilot remain with the craft from stationary start on ground to stationary stop on ground.)
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
I haven't been following it closely, but apparently some early experimental work has shown some exotic particles with imaginary mass!
You find yourself in this rather unusual state of affairs because the mass isn't measured directly. What you can measure works out to m^2 and it's always been a positive number. Until recently, when the number works out as a negative number. Hence negative numbers.
This would mean that gravity is repulsive between two objects of the same imaginary mass. But what's the attraction/repulsion between normal mass and imaginary mass?
Newton's laws get even weirder. Negative mass is annoying - if I push on it, it doesn't push back. It actually pulls me towards it. Push on imaginary mass and you get... what? Maybe it only responds to imaginary accelerations... and that answers the questions about gravitational attraction as well.
This is probably some subtle experimental error, even if the results have been verified at several sites. More data will show positive m^2. Or a subtle error in the design of the instrumentation.
Yet....
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
If you ever followed the research of Richard P Feynman and his like it's interesting to note that a matter/antimatter annihilation could simply be viewed as ordinary matter travelling normally one way, emitting huge amounts of energy, then travelling back the other way but backwards in time. It is well established that subatomic particles pay no attention to time whatsoever. We know matter contains lots of energy anyway. [E=mc^2, where c is lightspeed. Lightspeed squared = lots and lots of energy.]
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.
It's 10 PM. Do you know if you're un-American?
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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My apologies; I thought you were arguing that negative energy cannot exist, which is what I was taking exception with. :)
... because although its observable behaviour would be opposite, the effects on spacetime curvature would be exactly the same as positive mass
:)
:) Keep in mind that it's a first approximation meant to illustrate the point, nothing more.
So therefore it is always some positive value somewhere in the system right?
Not necessarily. The system is allowed to be at a zero-energy state. A lot of people believe that, from whatever point within the cosmos that you observe the cosmos, the net energy of the cosmos is zero. I'm not certain I buy this, but not because the idea is bad--just because I haven't seen evidence to directly suggest this.
My arguement is that "negative" energy, as you put it, would have the same effect within the universe as positive "energy"
You seem to be conflating mass and energy here. An equivalency exists between the two, but they're not strictly speaking identical to each other. A photon, for instance, has no mass--but due to its energy level, it can be treated as if it possessed mass. Discussing this more would quickly get extremely arcane, but a good astrophysics text should explain it much better than I can.
First, in many instances you're right. Whenever you see an energy-squared term, the cosmos doesn't care whether the sign is negative or positive--the squaring means the result is always positive.
But that doesn't mean in all instances you're right. As a very quick and primitive example, look at E = mc**2. Let's say you're watching a spacecraft zoom by at relativistic speeds. Its energy content is equal to its mass times the square of c.
Now let's say you slow down that spacecraft somehow. You reduce its kinetic energy content by applying an acceleration opposite to its direction. You're diminishing the energy--or, not to be too mathematical about it, applying negative energy to the system. You apply so much energy that you bring the spacecraft to a crashing halt. Before, it had E energy, and now you've applied -E energy.
Well, how do you get -E energy? -m times c**2, of course. So as you apply negative energy, you also confer a negative mass... so as the spacecraft slows down, its relativistic mass vanishes (negative mass applied) and it returns to its conventional rest mass.
Professional physicists will undoubtedly want to crucify me for this example.
Short version: negative energy levels are known to exist. Negative masses are necessary in order to make some of the equasions work out properly, but we don't know whether (a) negative masses can exist on their own, or (b) whether it's just an illusion created by the mathematics we use to describe the system.
As an illustration of (b), imagine a square-shaped yard that's a hundred square meters. How long is each side? Well, ten meters, of course. But the square root also means negative ten meters would give us the same answer. In this instance, the negative result is discarded as an illusion of the mathematics. The same basic principle might apply to negative mass--necessary to make equasions work, but doesn't really exist.
I suspect the answer is (b), but I'm not willing to make any wagers on it. The cosmos can be a really weird place.
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