They are still testing transpiration cooling for potential use in areas of super high heating but I think they decided a long time ago that the mass penalty of

They are still testing transpiration cooling for potential use in areas of super high heating but I think they decided a long time ago that the mass penalty of transpiration cooling was much higher than that of ceramic tiles. Nobody knows the true number of tanker launches yet but it's going to be a lot. The ship holds ~1500 tons of propellant and payload capacity to LEO is ~150 tons, so 10 is probably a decent first guess. Less if it doesn't need to be full, more if there are a lot of losses in the process. But 10 isn't so bad if everything is reusable. It's a different way of thinking about launches. What we really need is a propellant factory somewhere other than Earth. That sounds easier than fusion rockets.