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Subject: 
Re: Spacecraft propulsion (was: Ship Power Core)
Newsgroups: 
lugnet.space
Date: 
Fri, 17 Dec 1999 15:43:03 GMT
Viewed: 
850 times
  
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%.

  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 sources,
and the lack of radiation problems.

--
-Bones-
= http://www.necrobones.com/        = NecroBones Enterprises

Mr L F Braun wrote in message <38597F70.97485FF5@pilot.msu.edu>...


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




Message has 1 Reply:
  Re: Spacecraft propulsion (was: Ship Power Core)
 
(...) Although fusion propulsion is far better than fission propulsion, there are still faster things. For example, light drives. They work by emitting light backward, as so to move foreward, an you know what the specific impulse in that case would (...) (25 years ago, 18-Dec-99, to lugnet.space)

Message is in Reply To:
  Re: Spacecraft propulsion (was: Ship Power Core)
 
(...) 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 (...) (25 years ago, 17-Dec-99, to lugnet.space)

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