It's slightly less cynical than that - it takes about eight years to design a space mission and rocket, but doing the detailed design is expensive as hell, so i

It's slightly less cynical than that - it takes about eight years to design a space mission and rocket, but doing the detailed design is expensive as hell, so in order to meet a budget, they then change the mission, so they can go back to the vastly more affordable task of talking about doing work, vs doing work