Excellent source on Cosmic Rays (updated often)
http://helios.gsfc.nasa.gov/qa_cr.html

NASA on using PLASTIC to shield astronauts from high energy radiation due to solar flares, etc. (2005)
http://science.nasa.gov/science-news/science-at-nasa/2005/25aug_plasticspaceships/

Super old but interesting
Apollo astronaut report on radiation (1973)


Old but good article on Cosmic Rays (1996)
http://www.srl.caltech.edu/personnel/dick/cos_encyc.html

Gamma Ray bursts
http://w.astro.berkeley.edu/research/grbs/grbinfo.html