During the two years I worked on the shuttle program, the biggest problem I found was that United Space Alliance (USA), the Boeing-Lockheed conglomerate tasked with keeping the shuttle flying, has converted the program into nothing but a revenue stream, and resisted all change. We were attempting to design a better launch-control software system, and the existing employees fought us at every step, because the new system would invalidate decades of their archaic experience. They were reluctant to share details of the current system, every requirement was like pulling teeth, and in the process we discovered that they did not know the system very well at all, were just following scripted operations manuals. Engineering knowledge and innovation has left the shuttle program DECADES ago, leading to the decay of human spaceflight as a whole. When USA needed to fill a slot, they would just move a person from another position, regardless of their qualifications - many of the "software engineers" they assigned to work with us had NO software knowledge at all, were there just to provide a warm body and allow USA to bill more hours.