Why is there so much radiation in space?

Chris - The answer is that in space there's nothing to stop the radiation and so there's a million mile an hour maelstrom of cosmic radiation which is streaming off our own sun. If we didn't have the magnetic field of the Earth to deflect it away then it would be basting us in radiation. It would also be plucking away our water and our gases on our planet and we'd end up like Mars ultimately did. It isn't a safe and nice hospitable place in space. It's not just because of the use of fusion.