Many spaceflight fans struggle to distinguish between F9 and Starship and think success with one guarantees another. Go back and read what Fred Brooks writes ab

Many spaceflight fans struggle to distinguish between F9 and Starship and think success with one guarantees another. Go back and read what Fred Brooks writes about second systems. The super heavy booster is extremely impressive, particularly the raptor engines and control systems. Their engineers need to be commended for that alone. The weight is questionable and it isn't clear how much the performance is compromised but its still a very impressive vehicle and future engine refinements are going to help. The second stage remains a huge concern. The economics of Starship are predicated on cheap, rapid second stage reuse. That huge multi engine second stage is a lot more expensive than the F9's disposable single engine second stage. Creating a robust, rapidly reusable thermal management system for orbital re-entry is an unsolved problem. I don't believe anyone, including SpaceX has a solution. With time and huge amounts of money they can iterate through the other problems and likely do a controlled re-entry and recovery with the second stage but the vehicle isn't going to be close to reusable. It is a massive problem and I think it makes a fiction of the entire program and turns it into a money pit. If you piece the system out though. The engines, the control systems etc, there is a lot of good stuff there for another system. I think the Mars colonisation BS worked well to inspire the troops and raise money and political interest but they seem to be in a corner with this design. It is looking very possible this system will never enter commercial service.