So there is late game and late late game. Late game is like where is rocket defense now. But after you research everything there is no use for the labs; consequently there is no use for a big part of your factory. I propose this: in the late late game(where you will build space stuff) before a launch you need to calculate the trajectory (or orbit) and stuff and for that you need labs. So it behaves kind of like research, but it does not end and is not mandatory so the longer you do it the smaller the chance of your rocket crashing gets. If you just launch it, it will almost certainly crash, but if you have been calculating it for long, a bit more time will have a very little effect. I suggest using an equation like this: 1-(1-base)*(1-k)^(units*m) So units is just like research units but calculation units, base is the chance of success without any calculations k determines how bended the graph will be, and m how stretched it will be. So increasing base will increase the values in the beginning, but it has little to no effect later, decreasing m stretches the graph horizontally and the interesting part: increasing k bends the graph, the more bended it is the bigger is effect in the beginning and the smaller it is later.
0<k<1
0<m
0<=base<1
P.S. If you want the Excel file (Koub added the formula that allows estimation of units needed to achieve any percentage) and experiment, here is a link to download it: P.P.S I know I'm a nerd.