Originally Posted by pilotbob
It is interesting because these books were all written fairly recently...
1. The Time Traders 1958)
I thought it was strange that space travel was described as impossible; that would have been shown to be wrong within a couple of years of publication.
But the Van Allen belt was discovered in early 1958 - so maybe, at the time, it was considered an insuperable barrier to manned missions, and Norton was incorporating that idea.