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Radiation a Mars trip hazard?



 
 
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  #31  
Old February 12th 04, 04:24 PM
Mike Miller
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Default Radiation a Mars trip hazard?

Brian Trosko wrote in message ...

Won't effect neutrons, won't deflect high-energy photons. High-energy
photons hit the ship, you get a cascade of other high-energy particles.


Do you mean photons or protons cause cascades? I know protons do.
They're being looked at as sources of spallation neutrons in some
"waste burning" nuclear reactors. But photons?

Mike Miller, Materials Engineer
  #32  
Old February 13th 04, 12:37 AM
Paul F. Dietz
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Default Radiation a Mars trip hazard?

Mike Miller wrote:

Do you mean photons or protons cause cascades? I know protons do.
They're being looked at as sources of spallation neutrons in some
"waste burning" nuclear reactors. But photons?


Photons produce an electromagnetic cascade by pair production
and bremsstrahlung. There are also photonuclear reactions, but
these are relatively less important.

Photons do not make up much of the cosmic ray load, though.

Paul
  #33  
Old February 14th 04, 03:12 AM
Christopher M. Jones
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Default Radiation a Mars trip hazard?

Brian Trosko wrote in message ...
Toprope wrote:

What about making a large magnetic field by creating a large cage
around the ship? Doesn't use much mass and you get a large field. But
it would need to be strong enough to maintain shape while the ship
accelerates. A large magnetic field could use little energy to deflect
radiation and create a radiation free area.


Won't effect neutrons, won't deflect high-energy photons. High-energy
photons hit the ship, you get a cascade of other high-energy particles.


As Paul pointed out, photons with sufficient energy
to do this do not constitute a hazard on their own
(since they make up such a small fraction of cosmic
radiation). Additionally, neutrons won't be much
of a problem either since they are a very low
proportion of the cosmic radiation (effectively
zero). Solitary neutrons have a half-life of only
a few minutes, so they don't tend to get very far
away from their source at sub-light speeds.
  #34  
Old February 14th 04, 05:13 AM
Gordon D. Pusch
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Default Radiation a Mars trip hazard?

"Paul F. Dietz" writes:

Mike Miller wrote:

Do you mean photons or protons cause cascades? I know protons do.
They're being looked at as sources of spallation neutrons in some
"waste burning" nuclear reactors. But photons?


Photons produce an electromagnetic cascade by pair production
and bremsstrahlung. There are also photonuclear reactions, but
these are relatively less important.

Photons do not make up much of the cosmic ray load, though.


....However, solar flares _do_ produce a respectable burst of hard X-rays
and soft gammas, exposure to which is not particularly good for one's health...


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

  #35  
Old February 14th 04, 02:20 PM
Paul F. Dietz
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Default Radiation a Mars trip hazard?

Gordon D. Pusch wrote:

...However, solar flares _do_ produce a respectable burst of hard X-rays
and soft gammas, exposure to which is not particularly good for one's health...


I believe these will also be a small fraction of the radiation dose from
the flare. Most will come from charged particles.

Pul
 




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