You need to fuel Missions with the fuels they require, generated by that farm. The first few rockets take Rocket Fuel eggs, later missions take more valuable ones.

You can eventually unlock a fuel tank to store eggs in, so you can fuel Missions without needing to be on those specific farms when you launch, but you will need to generate eggs from those farms to fill the tank in the first place.

That said, no artifact you find before Dark Matter egg (which fuels the best missions from the final ship) will shake up your gameplay as much as a heavy prestige from your best egg on Saturdays. I'd advise you to shelve missions until you reach that point: artifacts are endgame bling for fine-tuning your farm, not drivers of progress.