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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."
im pretty sure it means measure of mass since the wieght depends on the gravity. And antimatter has mass.
There's an older (1999) article on nasa's site with a bit more technical detail.
Hogsback
Yes, antimatter has mass just like normal matter. Indeed, this is one of the things that distinguishes gravity from say electric charges. Gravity is always attractive, mass is always positive. With electric charge, positive and negative, and repulsive and attractive forces are possible and seen daily.
One can see this from the fact that matter has energy. E = mc^2 and all that. Antimatter has energy also, meaning you cant 'borrow' energy from the universe by creating some antimatter with negative energy. The flip side of this is that when you bring antimatter and matter together, they annihilate each other, liberating all their energy stored as mass into a burst of radioactivity. This presumably is the source of energy for the engines (or whatever) discussed in the article.
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When antimatter is made in the lab, it is stored in something called a "Penning Trap". Indeed, it is a type of magnetic confinement.
More info, here
You don't understand thermodynamics. Of course it takes more energy to produce than we get out of it. 2nd law of thermo. For spacecraft, small and light is better. Antimatter, per joule, is the smallest and lightest allowable by the laws of physics as we currently understand them.
The idea is that we can use wind power, solar power, or crude oil generated power to make the antimatter here on Earth, and then take antimatter into space with us. None of those other types of power exist in space (except solar, which doesn't exist for any practical purposes if you start using antimatter propulsion to go to other stars..which is entirely possible when you have an exhaust velocity equal to the speed of light..well, almost, since matter and antimatter produce neutral and charged pi-mesons when they annihilate. the neutral pi-mesons decay into gamma rays that spray in random directions very quickly, but the charged pi mesons don't. so the idea is to shape the exhaust flow by moving the charged pi mesons when an electrostatic or electromagnetic field before they decay).
You're a victim of the same mistaken thinking that the comments about the hydrogen power generation story a few days ago were saturated with.
Is antimatter really being used for medical imaging?
Absolutely. Positron Emission Tomography (a positron is an anti-electron)
Hogsback
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!
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....
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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!
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Nuclear efficiency is in between. While there is not complete conversion, there is some mass going to energy, unlike in chemical rockets.
Err, no, that is wrong. Chemical reactions transform mass into energy just as nuclear reactions do. It's just that chemical reactions transform a far smaller percentage of mass into energy. So, as you correctly point out, it's an efficiency thing. The reason is that chemical reactions work on the binding energy between electrons, whereas nuclear reactions act on the
atom's nucleus, where energies are magnitudes higher.
It's all rather confusing, since the number and type of particles are the same before and after the reactions, both for chemical and nuclear reactions. However, the assembly of particles have different masses before and after reactions. So where did the mass that was converted come from? Well, just as mass is equivalent to energy, so is energy equivalent to mass. The binding energy in atoms is mass, obeying E=mc^2. And that is the energy/mass that is freed during a reaction, be it a chemical or nuclear reaction.
Hope that didn't confuse things any further...
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The first shuttle was the Columbia, there is no shuttle enterprise. Learn the facts. Look through the NASA launch schedule and tell me if you see an Enterprise. Maybe you meant the Aircraft carrier. Oh wait the first aricraft carrier was not Enterprise and was certainly well before Star Trek.
The first shuttle to be launched into space was the Columbia, but the first shuttle actually was the Enterprise. The shuttle was used for research prior to the first real launch, and was flown by being attached to the top of a 747.
Basically they just say "hmm...let's just assume it weighs X, delivers power Y, and has lifetime Z" and see what vehicle design is possible.
The folks I talked to basically flat-out said they (NASA) don't do much research into that kind of stuff, and they mostly leave it up to the universities and private industry to come up with the technology. Of course, NASA does shell out mucho $$$ every year to fund research, but they don't participate directly.
If you're interested in what kind of research NASA and other government agencies are funding, you can head over to FirstGov and do a search on SBIR. That doesn't cover ALL of the research or development projects, but there are plenty of cool ones in there (stuff like using mech-like tech to enhance human capabilities).