I am also a strong supporter of unmanned astrophysical research.

So I fully agree with your point. The payback in knowledge from microlensing research, the major NASA observatories, LIGO/VIRGO, etc has been very impressive. On the other hand, manned interplanetary missions would probably be very costly in terms of lives and money given present technology. A manned Mars mission, poorly motivated and rushed, would be a crap shoot.