If we are to "conquer the space" we better come up with a near-instant communication system. Otherwise there will be a lag of ~4.6 hours in our coms being just as close (in space scale) as Pluto - if we use laser beams or other light base coms. That might be OK for exploration, but not really suitable for space colonization. Unless the plan is just creating unconnected colonies, at which point every colony can run their own fork and nobody would give a fuck about what the others are running.

Once you solve that problem, you've solved the 10 min/block problem, since you can use the near-instant system to keep the blockchain in sync all the time.