Subject:
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Re: Spacecraft propulsion (was: Ship Power Core)
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Newsgroups:
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lugnet.space
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Date:
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Fri, 17 Dec 1999 00:10:25 GMT
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Viewed:
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814 times
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Bones Dragon wrote:
> > It depends where you want to go, and how fast. Nothing that we have now
> > is remotely capable of interstellar travel on a time scale that we can
> > bear to wait for results.
>
> Cool, thanks for the interesting propulsion discussion. It's been
> a while since I've thought about these things, but it's always been
> an interest of mine. Personally I'd like to see some work being done
> on nuclear propulsion again as well. There were ideas in the works
> for fission-pulse engines prior to the ban on atmospheric nuclear
> testing. The thing is, if the projects are constructed in orbit or on the
> moon, then it could be done safely without risking atmospheric
> contamination.
>
> One of the ideas behind a nuclear rocket is to take fissionable
> material and eject it out the rear of the spacecraft and detonate
> it.. the resulting shock against a blast-plate propels the vehicle
> forward. By sending out a rapid sequence of small fissionable
> pellets, a relatively constant thrust can be achieved. The largest
> problem is how to detonate the material effectively since in
> a conventional nuclear blast, a certain "critical mass" is required,
> and for propulsion you want to use small but frequent bursts.
> An idea that was presented is to use anti-protons as the catalyst,
> which will annihilate in contact with protons contained within the
> nuclei of the fuel's atoms to start a rapid fission process...
Why fission? Just because it's easier for us right now to garner energy from
fissionable heavy minerals rather than the fusion of light ones? The concepts
for nuclear pulse propulsion for fission almost always have to be external to
the ship--radiation and retention of particles, I'd guess, would be the big
problems--but you could feasibly have a fusion "rocket" with a bottle *inside*
the ship. That way, instead of 7-10% of the energy being converted to momentum,
you could get much closer to 100%.
The fusion/pusher concept has been shown to be feasible. Graphite-covered steel
spheres survive fission blasts, making pusher-plates possible. In the 1960s,
using conventional explosives, a small test pusher-plate vehicle was pushed up
into the atmosphere, IIRC about 1000m (not nearly to space--but that wasn't the
goal). The fusion concept, like sustained nuclear fusion itself, is still
something of an elusive beast, despite the theoretical elegance.
-Lindsay
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Message has 1 Reply:
 | | Re: Spacecraft propulsion (was: Ship Power Core)
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| (...) from (...) concepts (...) to (...) *inside* (...) momentum, (...) Why fission? It can be done -now-. The technology exists. :) I agree, in the long run fusion is much better, because of the theoretical effeciency, and the abundance of fuel (...) (25 years ago, 17-Dec-99, to lugnet.space)
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Message is in Reply To:
| | Re: Spacecraft propulsion (was: Ship Power Core)
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| (...) Cool, thanks for the interesting propulsion discussion. It's been a while since I've thought about these things, but it's always been an interest of mine. Personally I'd like to see some work being done on nuclear propulsion again as well. (...) (25 years ago, 16-Dec-99, to lugnet.space)
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