Of course they are going to change their minds weekly!
If they come up with a solution now, then their task is done and they will be unemployed sooner. They have to justify spending billions somehow.
Would you come up with a fast solution if it would put you out of work? or would you have fun tinkering with ideas for a few more years and keep yourself employed doing what you enjoy?
*Actually I think they have enough projects to work on for the rest of their lives and soon the next generation of Space-Cadets will move up.