The Cans don't have to come back. It is overwhelmingly cheaper to leave them there and build more. (Scrap value of a Can on Earth is somewhere <$50k. On Mars, p

The Cans don't have to come back. It is overwhelmingly cheaper to leave them there and build more. (Scrap value of a Can on Earth is somewhere <$50k. On Mars, probably rather more.) You might gather up the Raptor engines and ship them home (with their bells cut off). It is the only export from Mars that could conceivably be worth the bother, and then only if you had a Can returning for other reasons.