In Jules Verne's "From the Earth to the Moon", written in 1865, the travelers encountered a problem and calculated a path to slingshot around the moon and return successfully to Earth. Apollo 13 used the same maneuver. A quick look at wikipedia shows that the knowledge to calculate this was known by 1777, maybe earlier.Agreed, the first manned flight to the moon, Apollo 8, was just over 55 years ago. They achieved Earth orbit, then relit the Saturn V's 3rd stage at the right time and for the right duration so as to achieve escape velocity and be pointed not at the moon but at where the moon would be several days later. Then they burned the Service Module's engine to drop into lunar orbit, and later to break out of lunar orbit to return to Earth.
NASA had also pretty much mastered orbital rendezvous three years earlier with Gemini 6 and 7.
Amazing to think so much of the calculating was done with slide rules (which are only good to three significant figures).
What Jules Verne's travelers didn't understand was the vacuum of space and the nature of gravity. Gravity is still a mystery.
Ed
