What happens to Bitcoin when we achieve interplanetary travel?

The thought occurred to me in the shower. What happens once humankind spreads across the stars, how would something like bitcoin work? Do we have the technology or the know how currently to communicate between planets? Is it even physically possible (I don't know any of this is, if some one does). If we can't does that mean each planet would become its own side chain? like BTC earth, BTC mars ect? Or would it be fine and work as per normal?