> It's not fair to compare the cost of something that is an incremental improvement on a huge body of engineering knowledge to what NASA is doing, here. Just t

> It's not fair to compare the cost of something that is an incremental improvement on a huge body of engineering knowledge to what NASA is doing, here. Just to be perfectly clear, are you saying SLS development also results in a lot of engineering knowledge? If so can you highlight what that knowledge would be -- propulsion, material, efficiency, avionics, manufacturing?