>rockets
>Deep space travel
Your joking right?
Perhaps, i don't know, a trifecta of spinning electro-magnetic generators that have the capacity to warp the electromagnetic field around it that let (micro)gravity to the work for it?
Maybe use an element we can synthesise from another element that was not "officially" known about until the late 90s early 2000s.
How odd that this particular element also happens to be a main part of a fictional storyline where Nazi scientists used it to travel to the moon in a very popular first person shooterfranchise.
The CIA is laughing at you from September, 1958.