Orion
Once you're in space, Orion isn't an issue. It's just the pesky part about getting past the atmosphere and all that biological stuff which poses a problem.
Freeman Dyson calculated that the cumulative cost of an Orion launch was 1-2 extra deaths per year due to fission products in the atmosphere and concluded this was too high a price to pay for a launch. Compare and contrast with most companies which would happily let hundreds of people die as long as their product is sold and marketshare increased.
FWIW one of the things which killed Orion was presenting the concept to JFK as a launching a multithousand ton "space forttress" into orbit capable of lobbing nooclear weapons at any location on the planet and dodging whatever was fired at it thanks to the manouevring capabilities inherent in the propulsion system. He was horrified by the concept and reportedly ordered it shut down the following day.
Biting the hand that feeds IT
