Reply to post: Re: Radiation effects methinks

I studied hard, I trained for years. Yay, now I'm an astronaut in space. Argggh, leukemia!

bombastic bob Silver badge

Re: Radiation effects methinks

"Just wondering if we could create an artifitial magnetic field arround our interstellar spacecraft to mitigate the radiation issues"

That would help against charged particles, but not neutrons nor gamma. For it to work against those, you'd need a lot of other particles trapped in there, too. That happens to be the case with the Van Allen belts, though.

Neutrons are particularly bad in that they case things to _become_ radioactive, or change the atom into something else (even if temporarily, like Nitrogen 16 from Oxygen in water that is exposed to a high neutron flux, as in a nuclear reactor, which after a few seconds, turns back into Oxygen 16, but you can easily measure the additional radioactivity just from the decay of N-16 to O-16).

High energy gamma radiation can disassociate chemical bonds, effectively 'cracking' them, or cause oddball recombinations of chemicals that would otherwise not form [this is, I believe, the mechanism by how radiation kills a living cell]. Anything that's considered "ionizing" will do this, more or less.

The best way to shield against gamma radiation is mass. Gamma interacts with atoms of high mass by ionizing the electrons, 'exciting' them, and they either absorb it [heating] or spit out lower energy gammas [scattering]. Other particles like free electrons, protons, and alpha, will be shielded by relatively thin layers of material, so you won't need a magnetic field at all - just need a decent hull on a ship, or a suit made of some kind of thick material for those.

Neutron shielding needs to scatter the neutrons and possibly absorb them. Materials that absorb neutrons are well known, boron and hafnium being two of them [used in nuclear reactors to control reactions, for example]. These materials deplete as they absorb neutrons, though, so they have finite life. And you might have to 'scatter' neutrons to bring the energy level to the right point to be absorbed. This means hydrogenous material to maximize the energy decrement per collision with a neutron.

Anyway, the magnetic idea isn't bad when you consider the Van Allen belts, but it's the ions they trap that are doing the shielding, and not the actual magnetic field. Actually, though, if a nuclear rocket had water as a propellant, and you could keep it from freezing, the water would be really good radiation shielding from the sun [and the rocket engine itself] - just keep it oriented 'that way' while coasting. actually liquid H2 would work the same way more or less for neutrons, but you would need something a bit denser to help shield gamma.

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