I really thought the article was a pretty interesting read. Okay, it might not be something for the near future, but I can definitely appreciate the thinking behind this.

It would actually make a lot of sense to use some form of cryptocurrency on interplanetary settlements. I think your idea of using lightning network for quick transactions, while relaying the transactions to the mainnet afterwards (slow), really makes a lot of sense.

I do really wonder how long it would take us to build a fully functional settlement on the moon for example. I would think that's where we'll start, seems a bit more reachable than immediately going to Mars.