What I'm going to say will probably not be very popular but I believe that NASA is an organization that has out lived its usefulness. Back in the 50' and 60' when NASA was first formed it had a goal, to get us to the moon. An it did that goal very well.
But since then it hasn't really had a goal. It has had projects of which most of them it has pulled off spectacularly. The hunt for extra solar planets, probes to the outer planets, and rovers on Mars. But it hasn't had an organized goal for the whole organization. With out a clear and visible goal nobody cares. People lose interest, and without the people having interest congress starts looking for other places to send money.
I believe its time for NASA to be repuposed from a active research and exploration to a regulatory agency. Much like the FAA They set the regulations for safety in manned space craft like the FAA does. Nasa should also be in charge of tracking satellites and setting orbits for them.
Most of its former duties for space exploration could be handed over to private industry now. NASA could keep a small hand in exploration I believe but most of that could be handed over to private universities.