An additional reason is that expertise died out with the end of funding. We had exactly one generation that tackled this problem - there has been no opportunity

An additional reason is that expertise died out with the end of funding. We had exactly one generation that tackled this problem - there has been no opportunity for them to hand down their experience. We're not starting from scratch, but we're certainly worse-off than we were at the end of the space race - scientists and engineers will have to learn from books and papers, rather than having an expert around to guide them.