It will be done with settlements and in large quantities/bulk if at all.
This is how most intercontinental shipping works. The products are made on another continent but when we purchase it, for the most part the stuff is already waiting at local warehouse ready to be shipped. But a lot of this shipping between continents is subsidized in various ways so in an ideal universe most things and resources will probably be produced/extracted locally.
But it seems there is room for delay in payment settlements for the large bulk interplanetary orders if it comes to that, but then locally the transactions will be more instant. Maybe off chain
(searching for container rocket didnt yield any results. but i assume there will be built some really big ones that can transport a ton of cargo if/when the penny for space travel drops)
That's how it's going to work for sure, but managing the cargo is no the problem, not even the delay of transactions themselves. The problem is about the delay of a full sync round, because it could allow for a lot of damage to be done, for even if it's reverted at the end in the blockchain by then such a large time-window could allow many other exploits.
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