I agree. I'm not an expert but the heat shield looks to me like the most uncertain thing about the project. I'm sure they can do better than the Shuttle, especi

I agree. I'm not an expert but the heat shield looks to me like the most uncertain thing about the project. I'm sure they can do better than the Shuttle, especially since stainless steel can go much hotter than aluminum, but I don't know if they can achieve reliable reusability without refurbishment. Heat tiles were part of ITS though, and Dragon has them, so SpaceX has been thinking about them a long time.