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Originally Posted by shakran
just out of curiosity. . .What is this doing in Paranoia?
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I figured since discussion would eventually veer off into the theoretical, and possibly even discussions of aliens and government conspiracis here would be the best place. If mods still feel knowledge is the best place for this (have gotten a couple PM's from some folks) then feel free to move it, its fine with me
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Originally Posted by Augi
Also I have seen a different style of light craft, where the large sail was parabolic and not panelled. To accelerate it there would be a large array of lenses in Earth orbit to focus sun light to propel it. ObieX, have you seen this one?
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I've seen a few designs so far, but not that kind of setup (focusing of solar light with lenses from earth) however i have seen similar ones, like one where a beam from a satelite is fired toward earth, then intensified on earth, returned to the satelite, and then dedirected toward the solar sail craft. The collection of solar light would probably be pretty efficient energy-wise compaired to the current methods because lasers take a ton of energy. Then again different forms of light/energy produce different effects so its hard for me to say. A setup like that may require huge orbital platforms and lenses. Something orbital would be used since night time would suck for the beam, and the lenses would have to be in the most efficient position to get the best use of the sun's light. Maybe having the lenses float in orbit around the sun, but trailing behind or ahead of the earth.
Annihilation Engine (aka Matter-Antimatter Engine) :
One idea for a matter-antimatter engine (from Time Life Voyage Through the Universe "Spacefarers"..description of a diagram): In a matter-antimatter engine, a frozen crystal of antihydrogen is levitated within an electromagntic field. Ultraviolet light knocks free a stream of antiprotons, and the magnetic coils guide the antiparticles toward the nozzle. When the beam meets a stream of regular hydrogen, the two annihilate eachother, creating energetic subatomic particles and gamma rays. The particles rush out the nozzle at 94% light-speed, flinging the craft in the opposite direction and eventually accelerating it close to the speed of light.
Since this type of ship would spew out so much gamma radiation the crew quarters would have to be pretty far fomt he engine, and would require a butt-load of shielding. Also creating hydrogen crystals was a problem currently iirc, let alone antimatter hydrogen crystals.
Here's a link to some information that is too technical for me if anyoneis interested:
http://www.stw.tu-ilmenau.de/~gm/maars.html
Also here's a couple diagrams, though they're not in english and, oddly, they seem to have holes in them lol.
Nuclear Pulse Propulsion
This type of engine uses "small" pulsed nuclear explosions to create a plasma for thrust. The problem with this is that it is currectly not legal to test/use nukes of really any kind in space. A couple projects are listed and explained here:
http://www.all-science-fair-projects...lse_propulsion
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Project Orion
The first serious attempt to design a nuclear pulse rocket was Project Orion, carried out at General Atomics in the late 1950s and early 1960s. Orion used large bombs, which was all that we knew how to build at the time, to react against a large plate attached to the spacecraft with shock absorbing systems. Careful explosive design maximized the momentum transfer, which led to specific impulses in the range of 2,000 seconds (about four times that of the SSME) to a theoretical maximum of 100,000. Thrusts were in the millions of tons, allowing very large spacecraft to be built.
A number of engineering problems were found and solved over the course of the project, notably related to crew shielding and pusher-plate lifetime. The system appeared to be entirely workable when the project was shut down in 1965, the main reason being given that the nuclear weapon test bans made it illegal to explode bombs in space.
Project Daedalus
Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society (BIS) to design a plausible interstellar unmanned spacecraft that could reach a nearby star within one human lifetime (set to be 50 years). A dozen scientists and engineers led by Alan Bond worked on the project. At the time fusion research appeared to be making great strides, an in particular, inertial confinement fusion (ICF) appeared to be adaptable as a rocket engine.
ICF uses small pellets of fusion fuel, typically Li6D with a small deuterium/tritium "trigger" at the center. The pellets are thrown into a reaction chamber where they are hit on all sides by lasers or another form of beamed energy. The heat generated by the beams explosively compresses the pellet, to the point where fusion takes place. The result is a hot plasma, and a very small "explosion" compared to the minimum size bomb that can be created using conventional means.
For Daedalus, this process was run within a large electromagnet which formed the rocket engine. After the reaction, ignited by electron beams in this case, the magnet funnelled the hot gas to the rear for thrust. Some of the energy was also collected to run the ship's systems and engine. In order to make the system safe and energy efficient, Daedalus was powered by a Helium-3 fuel that would have had to be collected from Jupiter.
Medusa
The "Medusa" design is a type of nuclear pulse propulsion which shares more in common with solar sails than with conventional rockets. It was proposed in the 1990s in another BIS project when it became clear that ICF did not appear to be able to run both the engine and the ship, as previously believed.
A Medusa spacecraft would deploy a large sail ahead of it, attached by cables, and then launch nuclear explosives forward to detonate between itself and its sail. The sail would be accelerated by the impulse, and the spacecraft would follow.
Medusa performs better than the classical Orion design because its "pusher plate" intercepts more of the bomb's blast, because its shock-absorber stroke is much longer, and because all its major structures are in tension and hence can be quite lightweight. It also scales down better. Medusa-type ships would be capable of a specific impulse between 50,000 and 100,000 seconds.
The Jan 1993 and June 1994 issues of JBIS have articles on Medusa. (There is also a related paper in the Nov/Dec 2000 issue.)
Project Longshot
Project Longshot was a NASA-sponsored research project carried out at the US Navy Naval Academy in the early 1990s. Longshot was in some ways a development of the basic Daedalus concept, in that it used magnetically-funneled ICF as a rocket. The key difference was that they felt that the reaction could not power both the rocket and the systems, and instead included a 300kW conventional nuclear reactor for running the ship. The added weight of the reactor reduced performance somewhat, but even using LiD fuel it would be able to reach Alpha Centauri in 100 years.
Antimatter catalyzed nuclear pulse propulsion
In the mid-1990s research at the Pennsylvania State University led to the concept of using antimatter to catalyze nuclear reactions. In short, anti-protons would react inside the nucleus of uranium, causing a release of energy that breaks the nucleus apart as in conventional nuclear reactions. Even a small number of such reactions can start the chain reaction that would otherwise require a much larger volume of fuel to sustain. Whereas the "normal" critical mass for plutonium is about 26 pounds, with antimatter catalyzed reactions this could be well under a gram.
Several rocket designs using this reaction were proposed, ones using all-fission for interplanetary missions, and others using fission-fusion (effectively a very small version of Orion's bombs) for interstellar ones. See antimatter catalyzed nuclear pulse propulsion for details.
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More coming soon!
