Well I finally get around to replying to the cosmic ray questions and I find that GB has done a fine job already including some good links I'm going to bookmark. They seem nearly as detailed as the two best sources I found in my personal space book collection.

Those of you who had questions might want to check out this page I found linked at one of GB's sites.
http://helios.gsfc.nasa.gov/qa_cr.html

I reviewed Spudis' "Once & Future Moon", Lewis" "Mining The Sky", Miles & Booth's "Race To Mars", Collin's "Mission To Mars", Zubrins' "Case For Mars", and Stine's "Living In Space". The last two were the most informative. Stine had the most general information and Zubrin had the most on how it relates to Mars Missions. The other two Mars Books agreed closely with Zubrin, but had far less detail. The others agreed in general that cosmic rays are indeed charged particles. GB's sources help explain the confusion caused by old terminology.

The only thing I can add relevant to the debate here is that according to several sources cosmic rays are primarily blocked by the atmosphere not the magnetosphere. If I'm interpreting information correctly, (which was not intended to answer the question at hand) the number of particles from the galaxy seem to be low at least in comparison to solar flares but much higher in energy allowing them to punch through the magnetosphere. The fact that the magnetosphere is able to trap solar flares may or may not be relevant. It might be possible for an atmosphere alone to handle it or the high number might mean more solar particles or secondary radiation would reach the surface.

Stine did a fabulous job covering the basics and the effects of cosmic rays. Zubrin does a good job speaking of probabilities and estimated exposure amounts even breaking it down to mission phases. Collin's brief overview estimate was within a factor of two of Zubrin with a very different mission plan.

According to Stine, cosmic rays do not directly cause cancer. They cause secondary radiation when impacting gas liquid and solids. Some of this is X-rays and gamma rays generated from the release of very high kinetic energies when the objects are slowed down. The rest are the typical fission products caused when other atoms are split due to the high energy of impact. This radiation in turn causes the formation of free radicals which can foul up the body's chemsitry in several ways including mutations which can lead to cancer.

Sheilding with metals can actually be dangerous because it increases the chance of secondary radiation from fission. Shielding with low molecular weight water and sand are better.

All of the above is my interpretation of what I read in the last few days. I'm most interested to hear from anyone who has studied these issues in detail or takes the time to read books or links with info on Cosmic rays.

Regards,
Mark