Lately I've read discussions that the deadly effect of radiation in space may be the ultimate barrier to mankind voyaging between the planets. It is said that the sheer mass of the shielding required to protect astronauts from months and even years of exposure during a mission would make the trips impossible. They say even if it doesn't kill them immediately, they'll all get cancer.
Tell me it ain't so! Are all our dreams of space exploration to be dashed by cosmic rays? Will we be limited to sending out robots instead of going ourselves? Please discuss just how much of a hazard space radiation is, and whether it will keep us Earthbound or not.