Musk: Yes in fact I'd go a little further and say that it has to be "fully and rapidly" reusable. There are two problems with the space shuttle. It is not fully reusable and it is not rapidly reusable; even the bits that are reusable. But if you think of something like an airplane, an airplane is fully and rapidly reusable. Or if you consider what did the Wright Brothers invent? They actually did not invent powered flight. They did not invent controlled flight. They invented controlled, powered flight. That was important.