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NASA to Research Antimatter Rocket
Fraser Cain writes "One of the dozen technologies selected by NASA's Institute for Advanced Concepts (NIAC) this year is Positronics Research's ideas for an antimatter rocket engine. Instead of 3100 kg of propellant on board Cassini, the spacecraft could get by with just 310 micrograms of electrons and positrons. Of course, making the antimatter can be expensive."
If they could make this work it would cut down the size of the object to be launched drastically. That would be a great thing, which in itself would make spaceflight more profitable. No more 3T fuel, fuel tanks, etc.
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Work out the chemistry on it. The simple truth is that unless there is a fundamental change in energy density of chemical reactions, there just isn't a lot more to ask of chemical storage. That's why there is the shift towards "power generation." This is really just a fancy term for changing from where there is a chemo-eletrical differential (i.e. positive/negative sides) to actively causing a chemical reaction that provides electricity; however, there are two problems with this approach. First, it is usually easier to ask the device to use less power. Second, power generation at a minimum produces heat, sometimes violently and excessively. Batteries are nice because they are generally quite safe, reliable, and (most importantly) currently mass-produced.
On a side note, super atoms seem to be a possibility on "rewriting" our understanding on chemical reactions.
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How much antimatter would it take to wipe out all human life on earth? My guess is in the 20g - 5000g range, depending on how it is "deployed". Anyone else have a better clue?
Why do I ask? Think about nuclear power. We are now worried about radioactive material falling into the wrong hands. Fortunately, we have some detection methods to make it a little harder to deploy. Now if antimatter becomes a common battery source (say SUV's have 1 millionth of a gram to make it run for the week), how hard would it be to make the ULTIMATE terrorist act?
Granted, the availability of antimatter on this scale won't happen for a few decades, if not centuries. But when it does... it will be interesting...
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Without so much more technological breakthroughts (who will of course make that whole project pointless, because totally new options would arise), building a antimatter rocket will be impossible.
First: containment-> Its hard getting long livetimes in a nice good storage ring that doesnt suffer massive accelerations and other nasty stuff launching from earth brings with itself.
Second: containment part two: To power it, you would need a energy source of such capacity that could feed an ion drive or equivalent just fine without the need for antimatter.
Third: containment part three: if it fails it will give the a real nice flash. ok, with such a small one this doesnt matter (a normal rocked exploding is also devastating, but a bigger one would be like a nuke on steroids).
Fourth: Production of anitmatter: current efficiency of antimatter creation is somewhere around absolute zero... dont know the the exact numbers (the article was a few years old), but with current technology it could very well take the energy production of the whole USA to create that much anitmatter... for a year or so...
All those points dont mean that it wont be possible (or even desirable) to build an antimatter engine, but the needed advancements are THAT far away, that every kind of basic studies now are pointless.
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ZPE is what they think is forcing the galaxies apart.
seems like lots of power to me.
BTW, purely empty space is not empty. there are constant creations of particles and their anti particles (thus servicing thermodynamics) popping in and out of existence in empty space. this causes a pressure to form and this pressure causes a force which can be used to extract energy.
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Humans like to find new territory and conquer it. We currently have exhausted the Earth's surface, except for the submerged and frozen parts. So we have to go somewhere.
That said,
Space propulsion may end up being a two-fold operation, with a rocket or rail gun used to break free of the earth or moon's gravity well and a deep-space propulsion unit used for the long haul.
Something like a solar sail or ion drive might fill the bill. An ion drive is relatively inexpensive, but doesn't give much push. If a chemical rocket or magnetic accelerator gets you started, an ion drive could work nicely.
You still need "HUGE" amounts of power for a rail gun or rocket, though.
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The upper end of your scale, 5 kg, amounts to E = m * c^2 = 5 * 9e+16 = 4e+17 Joules.
The Russian Tsar Bomba ---the World's largest nuclear weapon ever detonated on Earth--- yielded 50 Megatons of energy, or about 50e6 * 4e9 = 2e+17 Joules.
That bomb didn't kill us, so 5 kg of antimatter won't kill us all.
To put things in perspective, the Hiroshima bomb (15 kton) destroyed about 1.5 grams of matter. The Tsuami quake on the Pacific, last year, yielded about 30 Gigaton, or 6.4e+19 Joules. That amounts to about 600 to 700 kg of destroyed matter.
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But you have to keep in mind that these facilities weren't designed to create anti-matter... I'm sure that these facilities can be modified/upgraded to produce anti-matter in a more efficient manner, maybe even increase production by several folds....
Also, energy released from antimatter annihilation doesn't come out in a very usable form. From this article it looks like most of the energy comes out as neutrinos. Space is full of neutrinos zipping around, but they're pretty useless for energy because they don't interact with matter to any significant degree.
It sounds wonderful to have some bit of matter that can be fully converted to energy but I think we'll have commercial fusion power sooner than this can happen.
Maybe they could figure out how to make smaller, safer fission reactors for these types of missions? Maybe they could focus on fuel efficiency, perhaps even making small breeder reactors for space use?
After years of thinking I knew rocket propulsion -- via SF novels and popular works and, well, building small ones -- I took a policy course on space travel at CMU. Professor Morel (sp?) insisted that we learn the science first. I got all sorts of good stuff, and started poking around the engineering library for more.
I found, while researching my term project, a great book on advanced propulsion topics. This wasn't some popular work, but a collection of hard-core equation-filled research papers. There was stuff on what could be the next generation of fission drives, various fusion drive concepts, and antimatter propulsion.
Beyond the obvious containment issues, there is a BIG problem with antimatter propulsion:
The problem of opacity.
Antimatter / matter reactions produce gamma rays. These are extremely energetic and readily penetrate many materials.
This means that they are very inefficient when it comes to heating up a working fluid. The detail -short linked-to article glibly talks about shooting gamma rays into propellant. They will heat up the hydrogen or water or whatever you are using for a working fluid, but a lot of the energy will simply keep on going, and whiz right through the outside wall of the "combustion" chamber.
The one research paper which described a "pure" antimatter rocket heated the propellant indirectly. The positrons would be shot into a block of tungsten alloy dense enough to intercept an appreciable amount of the energy produced by the matter / antimatter reaction. Working fluid passed through channels in the block would heat up, turn to gas, and produce thrust.
The rated Isp was, as I recall, about 5,000 seconds. This is way more than conventional fluid / chemical rockets (500 seconds) and fission rockets (1,000 seconds) but only a little higher than existing ion thrusters (3,100 seconds for that solar-powered testbed that ran a few years back).
The one advantage this rocket would have over ion thrusters would be the amount of thrust. Ion rockets produce just a trickle of thrust. The antimatter thermal rocket would probably produce a fair amount of thrust, although probably not enough for a ground-to-orbit booster.
Stefan
Well, antimatter is pretty new stuff. We don't really know how hard it would be to produce if someone (a government or brilliant scientist) actually made a concerted effort to reduce production to an industrial process. Nukes are pretty hard to make since you need to get ahold of enriched uranium somehow. Presumably antimatter could be made without exotic, traceable materials.
Oh, and I'm not too worried about lost Soviet nukes. You need the same infrastructure you used to make them if you want to keep them working for any length of time. After fifteen years "in the wild", I doubt a lost nuke would actually work.
The antimatter must be one a hell of a job to handle safely. I don't see the future of antimatter fuel in a little light spaceships. Because of all the risks, only the large and heavy space vessels can be include all the necessary technology.
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