You can store a private key at long distances. You just can’t actively participate in the network when that far away. And you can use custodians for transactions in the meantime, like a checking account.
Discussion
Cashu, for instance, or opendimes, would work just fine, because you're not broadcasting anything to chain necessarily. Both would require trust at that point, as would any other custodial solution. But give them some sort of a seal that can't be broken, and maybe tie in WoT ideas to add in some tamperproofing, and i think given the circumstances you could arrive at something vaguely acceptable.
Still not better than subspace radio, but some science fiction actually tries to be plausible...
As long as all the hashpower is in one place it’s fine, you just wait longer to see the conformations. You can use a local lightning network on the same chain fine. It’s when the hashpower gets distributed that things start to fall apart.
Imagine if all the hash for a galactic currency was tied to one very small solar region.
This would from a pan galactic aggressors point of view be a single point of attack on the network, Satoshi would not be pleased! Space Zionist pirates are out there plotting to retake control always!
What about a galactic wide mesh network using instant quantum comms that combines multiple nodes to a single pan galactic BTC chain. Each star system could have its own sub chain running at light speed locally and obv our SOL system might be famous for being No 1 originating chain, some may call it Satoshis star.
Meh, now i need to shut up and read this book lol