A more challenging, yet vanilla feel to make space science more of a unique craft like the other introduced science packs. It helps integrate uranium mining into the tech path and gives uranium more utility I guess.

Making space science packs require uranium processing to discovered. I tripled the yield and made it only craft-able in a centrifuge.
15 Space Science Packs are made with:
1x non-enriched uranium
1x ice
1x carbon

Other than having to discover uranium technology, the real challenge is that you can only fit 20 uranium into a rocket, and that the centrifuge can only have 2 module slots. This is why I increased the science pack yield from 5 to 15. Let me know if this is too harsh in the early to mid game. I'm testing it now.

From the future here: Testing works great! but the true late game is crazy when it comes to rocket launches. A user 'Elocutiona' mentioned that 1000 science should come from a single rocket launch which is not possible with uranium-238 having 20 rocket capacity which I totally agree with.
Changing the recipe from 10 to 15 (as of 0.0.3) allows 50 empty fuel cell to achieve this. The end game goal is to build a platform that can produce an empty fuel cell a second in space or a base that launches empty fuel cells.

The calculations is assuming for 2x legendary quality modules in each step. (+50% prod bonus). 50 empty fuel cells > 45 uranium-238 > 1012.5 Space science.

anyway its something to do with uranium in the late game :)