Let see...

- Kerosene engines

- Small maneuvering engines

- Something to calculate the orbital maneuvers

And so on.


Personally, I think that technologies probably already existed in the
1930's, and perharps even before it. By the 1940's, nuclear engines
probably is much prefered than kerosene engines, just like in Herge's
"Objectif Lune" (which I suspect was done with help from outside
sources, it's just too detailed for a comic book).


Though it should be noted that there were ancient batteries and ancient
clocwork type devices already existed thousands of years ago, so it
could have happened thousands of years ago.