How would you colonise space?

[lawcat]

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[Moontanman]

I'm not sure what you mean lawcat, how does this equate to colonizing space or space travel?

[GAHD]

Originally Posted by Moontanman

The nuclear light bulb rocket does not release radioactive material into it's exhaust...

I have read this particular site (I think it was a few years ago actually). For sake of argument I have re-read it, and my original point still stands.

You may want to take a look beyond this one source. Lucky for me Wiki does have a quick gloss-over on the particular area I refer to(italicized and bolded by me for emphasis of important points)

"The fuel, evaporated by the heat produced by fission, is surrounded by liquid hydrogen. The gas core is contained by magnetic fields in a similar way to a tokamak. With such an arrangement, very high flow-out rates can be obtained, at the cost of massive radioactive contamination of the environment. Unfortunately it is not likely that this arrangement will actually work to contain the fuel, since the ratio of ionization to particle momentum is not favorable. Whereas a tokamak would generally work to contain singly-ionized deuterium or tritium with a mass of two or three daltons, the uranium vapor would be at most triply-ionized with a mass of 235 dalton (unit). Since the force imparted by a magnetic field is proportional to the charge on the particle, and the acceleration is proportional to the force divided by the mass of the particle, the magnets required to contain uranium gas would be impractically large; most such designs have focused on fuel cycles that do not depend upon retaining the fuel in the reactor"
-Gaseous fission reactor

If you want I can go dig up some articles from Arxiv regarding this specific subject, but I recommend you take some time yourself to dig around a familiarize yourself a little more with the subject area.

The rocket proposed by the site you link neglects that the rocket requires even more powerful magnetic fields to keep the gas from "falling" and burning right through the bottom of the reaction chamber during acceleration, or even while attempting to turn the vessel.

This is the very reason that most nuke bulbs do not separate fuel and propellant and the reason I in a broad sense say they would be too polluting.

It is a beautiful pipe dream but not practical IMHO.

[Moontanman]

I have wondered about the magnetic fields required but in this article the fusion gas is held behind a fused silica glass and does not contact the hydrogen. Unless the silica glass is compromised there is no reason for the uranium hexafluoride gas to leak into the exhaust.

[GAHD]

Originally Posted by Moontanman

...the fusion gas is held behind a fused silica glass and does not contact the hydrogen. Unless the silica glass is compromised there is no reason for the uranium hexafluoride gas to leak into the exhaust.

As long as the gas can be contained properly and kept from burning through it's confinement, yes this holds true. This leads back to the magnetic fields and their strength vs. acceleration, gyroscopic force(the gas is moving), tensile strength of the glass involved, contraction/expansion through heat, etc...

I'm not saying it's impossible, just highly impractical and dangerous for an Earth to orbit or reentry vehicle. The stresses on such craft are enormous. Once IN space it's a different matter, but I still say running a liquid lead or other metal as coolant for a "hot" reactor, and then using the coolant flow to preheat and ionize the propellant for an Ionic drive is much more safe and practical.

[Moontanman]

Actually the magnetic fields have been bothering me a little bit in another way as well. How do you generate a magnetic field without having the plasma surrounded by various wires and such that would not be transparent to the UV radiation given off by the gaseous core? to me this would seem to be a big problem. I love the concept but concepts are not always doable.