No, we would just keep beating on it until it works. It's a myth that science always precedes engineering. It's a very regular drift, and worst case scenario, if they just couldn't work it out, they'd build several ground stations in known locations, derive corrections as those drift, and upload corrections into the system periodically. (Similar things are done today: https://en.wikipedia.org/wiki/Differential_GPS )
Even with the science that we have, there's still fudge factors and empirically-determined values we have to use anyhow, because the Earth is not homogeneous and we have to take its slightly-lumpy gravity field as a given, not something we can "scientifically" determine. (Of course we "use science" to determine the lumps, but the lumps themselves are simply a given.)
That's not the question; the question is, are we forced to give up engineering if we don't have "the science" yet?
And the answer is an objective "no", from abundant past human history. There's this myth sold that science always precedes engineering that is very, very popular. I'm not even sure where it's coming from. Oral history in primary education, maybe. But it's a myth that engineers themselves can ill afford.
The vast majority of practical programming is programming running way, way ahead of the "science", which occasionally takes point samples of how 10 college sophomores behave under a certain limited experiment.
I don't understand why would you come up with such "objective" statements unless you really think it's not necessary to know anything about the history of science and engineering to have a strong opinion about them.
Well, humans have been crafting optical lens way before Maxwell ;). And even way before [1] Descartes and Newton decided to study light.
For everything out of reach of our senses, like the examples you gave, we need formal science. But for everything humans can see, smell or touch, we're pretty good with empirical observations : chemistry, fluide dynamics, genetics and mechanics where comonly used way before formal science was even a thing.
Possibly amended to include "to a degree that justifies the spending"
Fascinating to wonder how modern physics community worldview would be different, if GR had gone [empirical anomaly -> new theory], and ended up in the same place rather than [thought experiment -> empirical proof]. (IAN a historian of physics - forgive me if I have that wrong.)
> Alternatively (and more likely) we would have decided the idea simply doesn't work.
I don't think that's true. Consider the Bell Labs guys who won the Nobel Price for Microwave Background Radiation, who were just trying to remove the noise their antenna was receiving.
And hence have discovered GR in the process. Alternatively (and more likely) we would have decided the idea simply doesn't work.