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A very interesting article in the May 31 2013 issue of Science, "Measurements of Energetic Particle Radiation in Transit to Mars on the Mars Science Laboratory".

There are some assertions that the results agree with earlier predictions. I took a quick look at the attached document, but I am not sure that they agree that much. Has anyone else looked at it, and if so, would you care to comment?

Although the subject is of extreme interest to me, I am not an expert of space shielding and they keep talking about cosmic ions that they cannot shield against (they do not know how). So, what are these ions? And, how is it different shielding against them versus shielding against other particles?

Fedya, I also quickly browsed the Science article. I think the information given in the few opening paragraphs should answer some (many ?) of your questions. Here is my understanding of it. The Galactic Cosmic Rays (GCR) vary in species and intensity according to the solar cycle. The energy spectrum also varies from ~ 1 GeV for protons (which make about 85% of the species) to 500-600 Mev for heavier ion nucleons. About 1% of the particles are due to HZE (High Atomic number and high Energy), and their biological effects are very different and not understood very well. Then, there is also exposure to Solar Energetic Particles (SEP, produced by solar flares), which are protons of a few MeV but at *much* higher fluxes. So, they can shield against SEP much easier than they can shield against GCR, because of the energies involved with these particles.

Not an expert, either, and I hope I didn't confuse you even more