How about space science is still obtained by launching a satellite, but the victory screen is triggered by launching another Spidertron to colonize yet another planet?

Nice idea, but I don't think that it really makes sense gameplay-wise? What would the incentive be for launching a Spidertron?

I think I like the idea of infest other planets. Have some kind of extra reward. Maybe new OP spidertron upgrades

Would make more sense if combined with those space mods that allow you to send, trade or travel to other planets.

Well I think that the idea is that the spidertron that you send is infesting other planets and doing research in space, sending back its knowledge/spoils of war as science packs :)

Space exploration integration would be nice but I've never played it so I have no idea about balancing and I don't really want to modify the space science stuff in that because that would probably wreck the intended balance/progression.