> downplaying the difficulties of on orbit refuelling. Every single person I've heard say this hasn't given a reasonable reason why it's difficult other than

> downplaying the difficulties of on orbit refuelling. Every single person I've heard say this hasn't given a reasonable reason why it's difficult other than "we've never done it before". Also on-orbit refueling has been done, just not with cryogenics. Additionally it's only been done in zero-G with bladders. A slight vehicle spin to settle tanks seems like it would be sufficient to feed some low speed pumps without bladders.