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Antimatter Propulsion
er333 writes "A group at Penn State is building prototypes of antimatter storage for space applications, and makes a good case that with the amount of antimatter that will be produced in a few years, "omniplanetary" missions will become practical, including manned missions to Jupiter.
They have some images describing possible missions and a concept craft design called the ICAN II."
A decade ago, I worked as a lowly graphic artist at a nationally recognized think tank. I was looking for some Apache helicopter clip art in some files (paper files) when I came across some misfiled documents with the "Antimatter" heading. (These files were intended for graphics only, but someone had left the text on these particular docs - a security breach).
:-D
Anyhow, the documents matter of factly listed current positron output of the nation's accelerators, and output when taking into account accelerators coming on line in the next few years. They did mention antimatter as a fuel source for spacecraft, but more ink was devoted toward offensive weaponry.
Unlike some of the posters here, the military was not interested in creating antimatter bombs that could crack open the planet. Rather, they saw antimatter as a means to create extremely small devices with great destructive power, for "stealth" attacks. Imagine mailing an atomic-level letter bomb to an enemy leader! Actually, don't bother- someone already has imagined it.
Posting anonymously for obvious reasons
Looking back to the past from the present, we tend to forget the psychology of the day, instead seeing events through a filter of modern opinion and judgement.
:/
The Japanese (at least their military) were fanatical. Their country had never been successfully invaded by a foreign nation. They had the samurai mindset of death before dishonor. Even the Mongols who terrorized Eurasia couldnt do it: They sent the largest force of soldiers over water in the history of the world (unbeaten until WWI) and what happened? The Japanese gods intervened, sending a "Kamikaze" or "divine wind" that wrecked the Mongol ships after the first few battles. (And since the Mongols made the error of sleeping on their ships rather than making camps on the shores, they were all killed.)
Thats why in the end of the war they had suicide pilots (named after the supernatural forces they believed defended them). They were training civilians, women, to fight the Americans when they came. Running out of metal, they resorted to building balloons out of cloth and wood with incendiary payloads, and tried to float them over to North America to start massive forest fires. In short, they were doing absolutely everything they could to win. The Emperor knew things were lost, but go read what he said he was dealing with in the end: A pack of generals who were still adamant that they would WIN the war, not just successfully defend Japan.
But by dropping the atomic bomb, a weapon of unforseen destructive power, their mindset was broken: They realized that if they persisted in fighting, it wouldnt matter how hard they fought, they and their land and everything they were would be obliterated for all time in an atomic blast. Like a slap in the face to wake someone up from a delusion. So whenever you weep for those slain by the bomb (and you should), dont forget that it likely saved a lot more human life on both sides of the conflict, by bringing a swifter end to the war. (I admit though that I dont know why the second bomb was dropped.)
Sorry for the offtopic post.
Yes, many have noted that, including myself who is not an American and not as prone to many of their delusions. (Sorry guys.) Youll find the argument for the dropping of the bomb not only made by American historians, but by British and others if you look.
While you cant ignore the subjectivity introduced by the background of the person making an argument (or that of the sources they use), but also do not throw aside a persons argument in the hasty thought that they are not intelligent enough to make an effort at objectivity themselves.
It's funny how when this trait is present in our armies, we call it "courage" or "tenacity" isn't it?
Except that the level of fanaticism, or "courage" or "tenacity" or whatever else you wish to call it, wasnt there in, say, the European theatre. Theres a difference between fighting courageously and fighting a completely hopeless cause.
See the contradiction? If they were training all of these suicide pilots, what were they going to suicide in?
Planes that were already built, and modified to be packed with explosives perhaps? Those modified planes were extremely good bang for the buck: If one got through, you scored one sunken ship. All it took was one hit. Simple economics when youre in dire straits.
Ah, they were suicide balloonists, trained to float through the skys like a deadly horde of jellyfish, waiting for the chance to swoop down on helpless American fighters and explode.
Well, more details just to be serious: The balloon idea depended on the time of year: summer. During that time, prevailing winds blew from west to east, and also, the American west coast was experiencing a drier than normal summer, so their forests were like a tinderbox. The balloons were given enough helium to make it to North America, where they would run out and descend. When they got below a certain altitude, the charge would go off and an incendiary burst would result. No really expensive components, no fancy guidance systems. Did they work? No. :) Some balloons DID make it to the states, but most failed to detonate. I think one DID detonate, but it landed in the middle of a ploughed field and caused no major damage. At the time, the farmer and authorities had NO IDEA wtf was going on. :)
Along with a fair old chunk of the civilian population.
Regrettable, but as I said, perhaps that loss of life prevented even greater losses. Just something to consider.
Oh, further: Although some American generals really did just want to "blow stuff up" Im sure, they WERE considering it as a psychological weapon and not just a physical one. They were planning to blow up Kyoto (Japans former capital, and a spritiual center, it wouldve been like dropping the bomb on the Vatican) to really send a message to Japan but recalled that idea, fortunately for us all.
I wont deny that Hiroshima was a test. (It was selected since it hadnt been bombed much until then and would reveal best the results.) But I wont accept that it was only a test. The drop had a purpose, and that was to end the war. That was by far the primary reason for its use.
It's fairly clear why the second bomb was dropped, although these reasons don't stand up brilliantly in hindsight.
The Japanese civilian leadership wanted to surrender after the first bomb was dropped, but the more powerful military leadership refused. One of the reasons for this was that news didn't get from Hiroshima to Tokyo for at least a day after the first bomb was dropped, something that the american leadership failed to predict. The americans were therefore surprised that the Japanese didn't sue for peace immediately.
Another reason for dropping the second bomb was that Stalin declared war on Japan just after the Hiroshima bombing, and immediately attacked Japanese positions on mainland Asia. The Americans didn't want Stalin to win too much against Japan (the mindset of the cold war had already started at this point), so it was deemed necessary to get the Japanese to surrender immediately.
Throughout this you have to remember that six months earlier, the allies had won a war against Germany, with German divisions generally surrendering or retreating after 30% casualties. When the Americans invaded Guam and Saipan, the Japanese troops didn't surrender at all, and after ~90% losses, forced Japanese civilians on the islands to commit suicide rather than be captured, before committing suicide themselves. This event appeared in the American press, and the feeling was that if the Japanese defended a captured territory that strongly, then there was no chance of invading Japan.
A blockade on Japan would have hurt even more civilians, as food and fuel would have been cut off. Japan gets very cold in winter, and civilian deaths from a blockade would have been much higher than from the two atom bombs.
Most of this view is explained in "The Making of the Atom Bomb" by Richard Rhodes, which I admit takes an American viewpoint for most of the book, but I would say is fair at explaining the reasons the Americans had for dropping the two bombs.
In 3001, Clarke writes about an eerie explosion destroying an entire civilization due to mishandling of an extremely powerful energy source 500 lightyears from earth. Contextually, I think that was one of the few bits of the book that moved me much.
-l
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Yeah, I should've been more clear. I'd trailed off from the measly 1kg, thinking of larger bits, and didn't type all that out. Oh well.
-l
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Yes, antimatter as it is currently produced is quite inefficient. However, it is the most compact fuel that exists (in fact, it's the most compact fuel that can exist), so you don't need a whole lot of it. Since your efficiency starts going down exponentially once the mass of fuel is similar to the mass of the payload (and all current rockets are way beyond that point), even a very small amount of antimatter can replace an awful lot of fuel. Of course, what we really ought to be doing is to work for better antimatter manufacturing techniques -- now there is an example on what until recently was nothing but "pie in the sky" basic research now having an obvious application.
Antiprotons are currently created by slamming a proton beam into a fixed target (Beryllium, IIRC), which creates a shower of hadronic junk. A very small fraction of that is antiprotons. The junk is filtered to keep the antiprotons, and dump the rest. It's an extremely inefficent and expensive process.
--Bob
1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 1=0.
Or, there's the California definition:
For what it's worth, all full-auto weapons (capable of firing multiple bullets in sequence with a single trigger-pull) have been heavily regulated in America since the 1930s.
Clary, I guess this just means I'm agreeing with you...
Jon Acheson
All opinions expressed herein are my own, and not those of my employers, who are appalled.
According to our current base of knowledge of physics, antimatter is the end all of power generation. As far as propulsion goes, the biggest, baddest anti-matter drive that we can build can would only theoretically be able to travel us just shy of 1/2 the speed of light.
Actually, you can get to as high a speed as you like, just like with any other reaction drive. It just takes exponentially more fuel (the 1/e point for the cargo:total mass ratio happens when your ship momentum per unit mass equals the exhaust momentum per unit mass ("momentum per unit mass" is just velocity, for non-relativistic speeds)).
As for being the "end all of power generation", you're ignoring efficiency of power capture. Most of the energy from matter/antimatter annihilation comes out as gamma rays. You can't focus or reflect gamma rays. The best you could do for an antimatter rocket would be to use a big block of concrete to absorb all of the gamma rays going in one direction, pushing the block (and ship) in the other direction. This is far from being perfectly efficient.
Some proposed schemes use the mesons and other crud produced by proton/antiproton annihilations as reaction mass, directing them with magnetic fields, but most of the annihilation energy still goes into gamma rays, so you're only capturing a small fraction of the energy for useful thrust.
According to my own calculations, you *just might* be able to build a fusion drive that's more efficient in practical use than an antimatter drive (because it's not stuck with the very low thrust per unit energy of a photon drive, and can divert most or all of its exhaust in useful directions). Regardless of which is more efficient in practical use, fusion drives will be much, much, much cheaper (production efficiency for antiprotons is *extremely* horrible, and won't be getting much better).
All of this is ignoring drives that use an external power source, like laser sails or the Bussard ramjets mentioned by another poster.
Found this late while browsing through your comment history for signal processing posts. Hopefully you check for replies now and then. A couple of pieces of relevant information:
Indeed, its manufacture is highly inefficient. In fact, its maximum possible manufacturing efficiency is a mere 50% yield, and such a yeild is beyond the wildest expectations of most scientists. But, there is a much greater inefficiency involved here (actually two of them): acceleration energy and relativistic effects.
The problem is that antiproton production is something like a million-to-one inefficient. You could still do it, but it would cost far less just to build a laser array to remotely propel a solar sail (for interstellar travel), or to use fusion or fission drives (for interplanetary travel).
Assuming 100%-efficient magical synthesis of antimatter from electrical energy at 10 cents per kW/hr, it would cost $2.5 trillion per tonne. An antimatter-powered ship capable of interstellar flight within a lifetime would need to have about half its weight as fuel. Antimatter drives have great mass efficiency, but horrible energy efficiency. They work as photon drives; most of your momentum comes out as gamma rays, even with meson production from the antiproton reactions.
This gives a fuel cost of about $1.25 trillion per tonne of unfuelled craft weight (only half of the fuel is antimatter).
Plugging in realistic numbers for the cost of antimatter production gives quintillions of dollars. An array of lasers the diameter of Neptune still costs less.
Re. relativistic effects, you can avoid most of them by limiting your craft velocity to, say, 0.7-0.8c. That gives you a factor of about 1.5 mass increase and time dilation, which doesn't throw off your numbers much.
Re. carrying your reaction mass with you, you do indeed require exponentially more mass to gain velocity once your fuel mass dominates craft mass. What this in practice means is that instead of picking a speed and finding the required fuel ratio, you should pick a feasible fuel ratio and then find the resulting speed.
It turns out that a really-well-engineered fusion drive could give you tolerable interstellar travel times (a few generations), for far less cost than an antimatter drive. Or, you could use externally powered systems like solar sails or Bussard ramjets and still save money. The laser sail, at least, could be built with current technology (though it's still expensive as heck).
For interplanetary travel, a fission or fusion drive is more than adequate.
Thus, I don't think that antimatter will ever be a practical spacecraft fuel.
Now, a real issue to be investigated from the sun is (and, please, all ye experts on particle accelerators and animatter production, step in and comment (probably badly, sure, but its an idea)) whether or not you could produce antimatter from solar rays, which travel at a good percentage of the speed of light (sorry, no numbers on me right now). Most high-energy particle emissions from the sun are light nucleii, such as hydrogen and helium, but the sun does eject some denser nucleii. It'd be a free source of high-energy collisions, and you might be able to filter anitmatter from that in a fairly simple, low-weight, free-power (the main reason), low maintinence method, if you could set up simple automation.
The problem is that in order to produce antiprotons, you need particle energies greater than twice the rest mass of a proton - i.e. greater than about 2 GeV. The particles in the corona and solar wind are almost all of far lower energy, if I understand correctly.
I've never heard of lunar mass drivers before, but I'm quite interested :) Care to elaborate?
A mass driver is a ground-based device that accelerates cargo to escape speeds. Usually they're based on electrical, magnetic, or electromagentic principles (configured as giant railguns, coilguns, or other such devices).
The advantage to this is that you don't need to carry any fuel at all with your cargo, so the only energy consumed is that imparted to the useful cargo. This would be atou 60 MJ/kg launching from Earth, or about 3 MJ/kg launching from the moon.
On Earth, you'd have to worry about heat shielding on the cargo, keeping a barrel around the launch path so you can take out the air or otherwise reduce turbulence, powering the device, and just finding somewhere to put it. On the moon, you have no atmosphere to interfere with things, lots of space to build, and lots of space for solar power generators of various types. Sending material from the lunar surface to lunar orbit or interplanetary space is beautifully easy. This is why the moon is often proposed as a source of raw materials for space-based construction.
Moving material in from the asteroid belt would be expensive, because there's a great difference in gravitational potential energy between the belt and earth's orbit. You could use a near-earth asteroid to reduce this problem, but the moon's in a very convenient location and facilities there would be useful for many purposes, so IMO it's probably the best choice to supply any construction near Earth.
Re. mining, it would actually be pretty easy to attach a mining facility to an asteroid, either on the surface or inside the asteroid itself.
If the asteroid is in danger of crumbling, you can always turn some of its material into fiberglass rope and wrap the asteroid in webbing to keep material from drifting.
The weak gravity of the asteroid itself is still enough to cause most crumbled material to return eventually (a few hours for a medium-sized asteroid).
Stop crying about antimatter for chrissakes. It would take beaucoup amounts of it to turn into some sort of continent destroying weapon. And a funny thing about particle annihilations is THE VAST AMOUNT OF GAMMA RADIATION RELEASED which basically ionizes just about everything. High energy gamma rays can cause stuff to start transmuting, one caveat of antimatter ractions setting off lithium hydride fuel pellets is the lead shielding slowly starts transmuting into gold after a while and you also end up with fucked up equipment do to the Cherenkov effect. So anyways, antimatter bombs would cost upwards of a hundred billion dollars to produce just one. Even if AM production increased tenfold the price wouldn't drop too much. So a hundred billion dollars for a 40Mt bomb thats not quite as useful as a clean fusion bomb? Yeah right.
Aside from it not being used as a bomb, antimatter is a very good idea for use in spacecraft. It is the only way to get the energy you need for really long distance travel. And of fucking course any long term exploration projects will have AM production facilities in orbit, not because they're afraid of blowing themselves up but because its more efficient to not have to drag a heavy AM containment bottle up through the atmosphere. I think this will probably take around 50 years even if you account for increased levels of technology. The transition manned orbital stations to high tech production facilities on an extra terrestrial body is very large and requires a good deal of infrastructure to be built up. Before you have regular lunar travel you need craft capable of cheap hypersonic flight; this is the first step which gets alot of mass out of the signifigant part of the atmosphere. Once we're regularly scheduling flights from New York to Tokyo that take under two hours we'll have the capability to start building permenant and industrialized lunar bases. This is still 15 to 20 years off. We're well on our way but it will take time because there is little driving need to enter space in any hardcore fashion; political pressure got us to the moon. In an era of cooperation in space we'll be hard pressed to launch any crash space development projects in the near future. By the way a Saturn-V rocket carries no typical propellent, merely a pressurized container filled with hot air collected from the general hubub caused over the soviets beating the Americans into space.
I'm a loner Dottie, a Rebel.
It's those pesky social engineering issues again. If people are apt to go critical over nuclear power (like I mentioned in comments to the Mars and coffee story a couple weeks back), just think how they'll react to a proposal like this after decades of science fiction and Star Trek conditioning them to think of antimatter as insanely dangerous.
--
Editor Emeritus and Senior Writer, TeleRead.org
It's worth noting that an antimatter drive would be efficient in the same way that an electric car is a zero-emission vehicle.
Once the electricity is in the car or the antimatter in the spacecraft, the system is very efficient/nonpolluting, but the preparatory process of making the electricity/antimatter is still fraught with regular industrial-age inefficiency and pollution. Of course, for a spacecraft this is ideal, as it's a lot more effective to have all the hardware on the ground instead of carrying it with you. I only say this to forestall people talking about such a drive as an ecologically friendly alternative.
Kevin Fox
--
Kevin Fox
Despite a 100% matter to energy conversion rate antimatter has got to be one of the most inefficient fuel sources out there when you look at the entire picture! We'd be conserving resources by making coal-powered spaceships...
:-)
But when you think of the sheer amount of fuel necessary to brute force REALLY long-distance missions, the numbers quickly expand exponentially. I keep thinking how big a rocket would be required to lift a saturn-5 into orbit.
However with antimatter, a kg of antimatter would take you virtually anywhere in the universe and back. Some missions would never be achievable within a human lifespan without antimatter, but with antimatter, high acceleration could be maintained for long long periods of time, significantly shortening the journey.
So looking at the entire (long-term) picture, antimatter seems like the answer.
Of course, if we can find replenishable sources of coal on other planets, maybe we'd better go that route...
Paul
You are lost in a twisty maze of little standards, all different.
There are other sides to this though. Eventually, as time and technology progresses, it will become a lot cheaper than it is today to produce anti-matter in quantities sufficient to fuel huge numbers of missions to Mars, Jupiter and beyond. Such technology shouldn't be ditched because of expense when it's potential is so huge.
As regards the potential use to the military, increased fuel economy in motor vehicles is also beneficial to the military... but because it benefits everybody else also, work in this area continues apace. Nuclear power, much as I dislike it, is clean and efficient and yes it produces a byproduct that can be used in weapons of mass destruction.
We can't really complain about the potential military uses of new technologies when assault weapons are on sale to Joe Soap in the worlds more powerful country.
Bzzzzzt..."AAAAaaaaarrrgh!!!" Thud.
"civilian deaths from a blockade would have been much higher than from the two atom bombs."
Except of course for the effects of radiation that we probably didn't anticipate (there wasn't enough time to bomb Native Americans in New Mexico over several generations to see the effects, oh well). So AFAIK we basically doomed several generations to all sorts of f*cked up genetic problems.
It's 10 PM. Do you know if you're un-American?
"The balloon idea depended on the time of year: summer."
Don't forget, us Americans had some pretty cockamamie ideas too. For instance, taping explosives to bats...yes *BATS*...and sending them over to Japan. The idea was that since most Japanese buildings were made from light wood and paper, that we could burn them down easily.
It's 10 PM. Do you know if you're un-American?
While we're all talking about potential military misuse of the technology and the destructive power of antimatter, aren't we overlooking one of the coolest things about this research? The second page of the article talked about one of the side-effects of antimatter production was the creation of O-15 which is used in PET scans.
Storage of antimatter is a challenging task, but reaps several benefits. One of which is the generation of O15, a radioisotope used for Positron Emission Tomagraphy (PET) of the human brain. Currently, only certain research hospitals across the world have the ability to create Oxygen-15. Due to its portability, a "radioisotope generator" antimatter trap may be transported to more remote areas for patients who cannot reach these hospitals. A second medical application concerns antiproton radiotherapy of tumors. The NASA Penning trap is being designed with these medical applications in mind.
This fact would potentially offset some of the negatives that antimatter has.
It amazes me the wonderful side-benefits we get from basic research and space research sometimes. Who would have thought that research on propulsion would provide an alternative means to create a rare but medically necessary element in significant quantities?
at least it's a 43 Megaton CLEAN explosion, vs a glow-in-the-dark-til-Y3K explosion.. Still a problem, but at least it's over in a few milliseconds :)
//rdj
No one can understand the truth until he drinks of coffee's frothy goodness.
--Sheikh Abd-Al-Kadir, 1587
According to our current base of knowledge of physics, antimatter is the end all of power generation. As far as propulsion goes, the biggest, baddest anti-matter drive that we can build can would only theoretically be able to travel us just shy of 1/2 the speed of light. This assumes the fuel to generate the acceleration is carried by the drive. Obviously, we'll need to cheat relativity somewhere to get around this little problem or devise methods of acceleration which don't carry fuel.
Someone you trust is one of us.
One other thing to consider is that if you just drop a 1 kg ball of antimatter onto the ground, the entire mass of antimatter isn't going to all annihilate simultaneously, since the outer layer is going to come into contact with matter before the inner part of the antimatter ball is. For the maximum yield, the idea would be to have every particle of antimatter contact an equal-mass particle of matter simultaneously, but that's clearly not a trivial task (if it's even feasible).
:) Sort of like a gigantic sparkler...
:)
Eventually all of the antimatter in such a "ball" would annihilate with regular matter, but certainly not all at once -- the initial contact with, say, the atmosphere would cause maybe the outer 5% of the antimatter ball to annihilate "simultaneously", however, this would cause a gigantic enough explosion, and the rest of the antimatter would be dispersed into a cloud that, shortly thereafter, would start reacting with atmosphere. It would be an explosion that would take 10-15 seconds to actually occur!
My numbers are probably off but I think my theory is correct. I *think*.
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
An antimatter explosion would probably look more or less identical to a nuclear explosion. In fact, any sizable explosion in atmosphere will produce a mushroom cloud; the particle mechanics involved with nuclear and antimatter explosions differ, but the large-scale effect is the emission of lots of EM radiation (light and heat and all across the spectrum), as well as a great deal of kinetic energy (the shockwave). A 20 megaton hydrogen bomb explosion and a 20 megaton antimatter bomb explosion would probably be mostly indistinguishable.
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
Anti-matter propulsion, neural-nanonics, h4wt habitat chyks, Norfolk tears... Bring it all on! Except for the undead. They might ruin it for the good kids.
The opinions contained in this document are in no way expressed.
I think you'll find that you are out by a factor of 1000. The post said 10nano-grammes - not 10nano-kilos. The other point is that should it not be 2x E=mc^2 for AM conversion - as there is 10^-9 grammes of anti-matter and the equivalent matter converted to energy.
The opinions contained in this document are in no way expressed.
Penning trap + diagram
Ok, first off, a number of people seem to be missing the point on this article (largely because most of them read little more than the introduction, if they made it through that), so I figured I'd cover some of the details better.
:) ). In a chaotic sea of reactions such as the sun, yes, you'll get a little antimatter, and it'll go away just as quickly. Of course, you could harness solar energy to produce antimatter by having a manufacturing station near the sun, but you could harness that energy for a lot of other things too, and we get to the economic feasability issue discussed in the last paragraph.
:) I don't see economic viability in bringing it into space at this point.
Misconception 1: Antimatter is a poor choice for a propellant because its manufacture is inefficient.
Indeed, its manufacture is highly inefficient. In fact, its maximum possible manufacturing efficiency is a mere 50% yield, and such a yeild is beyond the wildest expectations of most scientists. But, there is a much greater inefficiency involved here (actually two of them): acceleration energy and relativistic effects. Picture a system where you have 10% of the mass as propellant. Then, you're wasting 10% of your energy merely accelerating the propellant (roughly - the propellant, naturally, will decrease in volume). Now, picture a system where 99% of the mass is propellant. That's a 99% energy loss. Well, even at those weight levels, the best chemical propellants can't get you very fast. To make matters worse, we have relativistic effects which, the faster you go, the larger portion of energy it takes to accelerate you. At 1/2c, energy requirements are doubled. So, mass is an incredibly critical thing. In addition, the speed exhaust particles are propelled is, if anything, more critical, because it sets a maximum theoretical speed for the craft - and for chemical rockets, it is incredibly slow. And to get close to that speed requires massive waste.
Misconception 2: Antimatter is a great concept for a weapon.
In actuality, no. Due to the huge manufacturing difficulties mentioned before, it is a poor weapons concept. Even with the proposed efficiency increases, manufacture is expected to cost several billion per gram (a gram of antimatter has roughly the energy potential of 27 of the space shuttle's solid booster rockets). This level of explosive power doesn't really compare at all to a boosted thermonuclear weapon, which isn't that incredibly expensive to build (U235, for boosting, is incredibly cheap, and the rest is a standard hydrogen bomb core). It isn't even that good of an idea for a small stealth weapon, given our current scientific knowledge. Containment for an amount of antimatter that would be enough to take out merely a building hasn't been developed; the smallest containment systems we have for antiprotons are roughly 2m by 1m by 1m. You'd be better off with conventional explosives.
Misconception 3: Antimatter storage is dangerous
Not with the amount we're dealing with. The mars mission proposals were planning to use 100 micrograms of antimatter, to start fission/fusion in tiny spheres. If it were to detonate, it'd be a smaller explosion than the challenger had, to say the least. The real worry would be the fissionable material causing a chernobyl-like effect apon a small area (this has happened in the past when we've had nuclear weapons accidentally "detonate" - not a nuclear explosion, of course, but a conventional explosion which scatters the radioactive material around). There'd be no need to do anything like "hiding it behind the moon". We don't worry about space shuttles and satelites blowing up many miles above us. We need to worry even less about this.
Silly Misconception Someone Made: Antimatter should be manufactured in space so we don't have to ship it up.
The main concern with shipping things up to space is the mass requirement. The antimatter we're dealing with has almost no mass, relatively - only its containment units do, and they'd need to be brought up even if the antimatter was being produced in space - in addition to *an entire antimatter generation facility*, personell to run it and maintain it, power generation, etc... oy, what an economic nightmare! There are much better things to work on producing in space.
As for the issue of "converting solar energy to antimatter", well, that's a tricky question. The sun does not release antimatter; that'd be silly. Antimatter has this lovely habit of detonating virtually instant with regular matter (that's why we love it so!
Now, a real issue to be investigated from the sun is (and, please, all ye experts on particle accelerators and animatter production, step in and comment (probably badly, sure, but its an idea)) whether or not you could produce antimatter from solar rays, which travel at a good percentage of the speed of light (sorry, no numbers on me right now). Most high-energy particle emissions from the sun are light nucleii, such as hydrogen and helium, but the sun does eject some denser nucleii. It'd be a free source of high-energy collisions, and you might be able to filter anitmatter from that in a fairly simple, low-weight, free-power (the main reason), low maintinence method, if you could set up simple automation. It'd need to automatically stabilize its orbit and adjust its distance from the sun according to conditions, to eject containers from earth when its on the right trajectory, etc, but it is doable. But, in reality, I recommend sticking with antimatter production on earth for now
- Rei
Look at me, still talking while there's science to do.
>I've never quite understood this - how can you >store antimatter, why don't the >particle/antiparticle pairs annihilate each >other? I'm grasping at nothingness here, but >I've always visualized antimatter being stored >as a non-gas in a vacuum, out of contact with >the container.
The trick is to use magnetic confinement, don't allow the antimatter to touch the container.
Problem is : antimatter produced in accellerators is insanely hot, so you need extremely strong magnetic fields to confine it, at least until you can cool it down. We'll have "regular" nuclear fusion figured out a long time before we can reliably produce antimatter in significant quantities. I'm not even going to mention the safety issues connected to storing considerable amounts of antimatter. Any failure of the confinement field would result in a big badaboom (making Hiroshima look like a fart in a bottle...) - you wouldn't have to much trouble with radiation afterwards though, but when you're vaporised, you tend not to care too much...
Could you define assault weapon? The US Congress has had a hard time doing it, resorting to listing specific weapons by make and model, or enumerating seemingly irrelevant features like flash suppressors and bayonet lugs.
Hint: If you were going to say an assault weapon is a machine gun, then you miss the point. A military person might expect an assault weapon to be capable of fully automatic fire, but machine guns are not the target of the recent "assault weapon" furor in the US. Fully automatic firearms are already so heavily regulated in the US that it is inpractical for most citizens to own them.
"Rub her feet." -- L.L.
Nope. I think you may have misunderstood what your professor was saying. Total annihilation of 1 kilogram of matter will produce about 8.9E16 Joules of energy (E=mc^2). There are about 4.2E12 Joules in a kiloton of TNT equivalent, so this is roughly equivalent to a 21000 kiloton, or 21 megaton nuclear bomb. A big bang, certainly, but not anywhere near enough to destroy a whole continent. Many nukes of that size (and larger.... 50 MT and up) have been detonated, and as far as I know all the major continents are still here. :-)
Of course, the kilo of antimatter will also wipe out a kilo of normal matter, doubling the yield, but that's still not enough to vaporize a continent.
Well, the last time something was called ICANN, they couldn't. I just hope these guys can...
There are two kinds of people in the world: Those with good memory.
Run the numbers. The amount of energy in any given amount of AM is given by:
E = m*c^2
You have on the order of 10^-9 kilos of antimatter, and c ~= 3*10^8, so c^2 ~= 9*10^16. Therefore, the amount of energy is on the order of 10^(16-9) = 10^7 joules.
So, if you have a spontaneous release of all the antimatter currently in existence, you're talking about the release of a few megajoules of gamma rays. Not too serious, unless you're standing right next to it or are in the immediate vicinity. Certainly not on the order of a tac nuke.
I think you'll find that you are out by a factor of 1000.
Oops. My bad. Should be 10^-12.
The other point is that should it not be 2x E=mc^2 for AM conversion - as there is 10^-9 grammes of anti-matter and the equivalent matter converted to energy.
That shouldn't (generally speaking) affect the order of magnitude of the amount of energy produced. Depending on the exact numbers, you'll only get an increase of a factor of 10.
... that currently, it's really hard to produce - as the article says there are less than 10 nanograms currently produced each year, and the projected yield from Fermilab's new equipment would be no more than 140ng or so. And this requires huge particle accelerators costing billions of dollars.
And even when you've got these going, the cost to run them is prohibitive. And then there's the problem of keeping them stored for long periods at a time and transporting them. Despite a 100% matter to energy conversion rate antimatter has got to be one of the most inefficient fuel sources out there when you look at the entire picture! We'd be conserving resources by making coal-powered spaceships...
So Bush is probably going to love this :)
And an increased capacity to produce antimatter, while way out of our reach at the moment, brings new problems with it. After all, matter-antimatter reactions are far more efficient than even fusion reactions at converting matter to energy, and the military uses for this are obvious, especially to anyone who has read the Night's Dawn trilogy. It wouldn't suprise me if this sort of thing is being investigated somewhere as a speculative new military tool.
Hopefully, I'm just being paranoid. But given the military's obsession with technological superiority, I doubt it...
Well, at least when Penn State implodes in on itself and dissapears, we'll have an idea about what happened.
-S
--- What parts of "shall make no law", "shall not be infringed", and "shall not be violated" don't you understand?
The original CAN was built by NASA in the fifties as the prototype crew module for all of the Apollo missions.
During the late 90s, with the cold war over and budgets dropping, NASA had to make space travel more appealing. As a result, they created the iCAN. Similar to the shuttle, the iCAN's engines, the crew module and all the rest are enclosed in a single module. While it makes upgrading the iCAN harder, it does allow the iCANs to be produced at a lower unit cost. Perhaps the most important advance for the iCAN was the addition of clip on heat shielding that came in a variety of attractive, transulcent shades.
While the iCAN saved NASA at the time, Russia has been coming up with more and more powerful rockets that, while harder to use, have outpaced the once popular iCAN. As a result, NASA have re-released the iCAN in its new iCAN II form. New features include patterned as well as coloured head shielding and the ability for astronauts to listen to and rip MP3s.
Note: You will probably see the iCAN II referred to as the ICAN II. Don't be confused by the capitalisation change, it's simply NASA trying to lose the dated late 90's i feel.
In Peter Hamilton's Night's Dawn trilogy, they make antimatter in small space stations located very close to the sun. Lots of energy there :)
Ok maybe "easy" is overstating it, but anyway..
A much more interesting part of those books is that antimatter is outlawed, due to its potential for mass destruction. I'm no expert on this, but isn't that essentially correct? If larger quantities than a few nanograms are produced, aren't we dealing with something extremely dangerous here?
-- If no truths are spoken then no lies can hide --
HUMOUR TYPE="in-joke" CLASS="slashdot"
/HUMOUR
Hmmm - looks like the ICAN II is not equipped with hexagonal jets. I guess the designers at NASA haven't been spending enough time in 1950s bathrooms to truly understand the subtle complexities of Zarathustra, Odysseyus and why the Trojan horse has "NO MEAT".
There are a thousand forms of subversion, but few can equal the convenience and immediacy of a cream pie -Noel Godin
Just look at Switzerland - the oldest democracy, and they are required to be armed.
Well actually Switzerland is not the oldest democracy. Anyone who's taken a bit of history knows that Athens was the first state to institute democracy. And even the Roman republic held elections. The first 3 Swiss cantons to create the confederation that eventually grew into the country of Switzerland first banded together in 1391, and the vikings had a system of elected chieftains and kings much earlier than this. As for where one draws the line of real "democracy" - the Swiss have always had a tradition of communal consensus in their government - but there was no established or pan-Swiss standards for this until Napoleon came and reformed the country's federal government in the image of the french republic.
As for the military tradition here, you're quite right - every man between 18 and 40 is required to do 2 weeks of military service every year. They are required to keep their military weapons and ammunition in their homes so that they can be ready to go to fight at any time. The Swiss Alps are riddled with bunkers, hidden gun batteries, underground tunnels etc. Also every building larger than a house built since the 1950s has to have bomb shelters in the basement - and the local governments maintain lists of how much bomb shelter space there is and who is assigned to what shelters.
It is interesting to note that the two countries with the lowest rates of violence with firearms in the world are Sweden and Switzerland. Sweden has the lowest personal gun ownership in Europe and Switzerland the highest. Just goes to show what culture does for people.
There are a thousand forms of subversion, but few can equal the convenience and immediacy of a cream pie -Noel Godin
Boss: You've been watching a Star Trek marathon again haven't you? How many times do I have to tell you; you *can't* build anti-matter spacecraft!
Engineer: I can too! Hey that sounds catchy..._ __
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It blows my mind that we're actually discussing putting a man (or woman) on Mars using an anti-matter propelled craft that will be assembled and launched from an orbiting space station. The fact that we're capable of such a thing absolutely amazes me. It's even more amazing when you realize that space exploration is less than fifty years old.
To put things in perspective, my father remembers Sputnik. My grandfather got around town in a horse and buggy. I wonder what my kids will get to see...
This
Ok, what we know about modern physics is solely based on experimentation. We don't know why shit works, we just know that is does. Therefore you guys saying this is unfeasable or shouldn't be done, should stfu. Just accept the fact eventually we will be using antimatter drives and be leaving our solar system. Also whoever said it would take a huge amount of time to reach alpha centauri is an idiot. How can it take more years than miles?? Sure it would take a long time, but not billions of trillion of zillions of whatever years. Given constant acceleration and deceleration, prolly take 10-20 years. Which is a long as time, but still no huge ass number like you mentioned. Anyways, I just thought it was funny when you guys were talking like you know shit when I know nobody here does, including myself.
Well, maybe they're going to search for new domain names on Jupiter when we run out of them here.
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No message.
-- Imperial units must die --
ICANN II just uses 140 nanograms. I wouldn't want it dropped on my house, but it won't vaporize a continent.
I'm the stranger...posting to
ICANN II uses 140 nanograms of antimatter for a thirty-day run, but if we want constant acceleration/deceleleration (and I assume we do, so it can reach the Oort Cloud in fifty years), won't it need a lot more antimatter? 140 times 12 gives you the amount of antimatter used in a year, 1680 nanograms. Multiply that by fifty, and you get 84000 nanograms. That still may not sound like a lot, but that's actually a respectable bang - look at the web page mentioned in this news post. Could someone check me, and see if I'm wrong?
I'm the stranger...posting to
Okay I'm not sure if anyone has mentioned this or not, but Remeber back in, was it 97?, when seemingly the entire universe was just freaking out over the idea of lauching Plutonium into space in the form of Radioisotope Thermoelectric Generators. Now weather or not the risk was worth it is not my point. My point is, Casssini maybe would have caused a couple of thousand deaths from fallout worst case scenerio, and if I read the article right (as in they may need a kilogram of this stuff) then if this probe/ship messed up ANYTIME during shipment, thats a 43 megaton explosion from what i've heard. Now *I* am not saying we should not advance our technology and explore space, all I am saying is if a little plutonium upsets people imagine how they would protest a anit-matter launch that could prolly destroy the state of Flordia.... Just a thought