The Shuttle program has alwasy been a boondoggle. There has been not one significant piece of science that has come out of it. Robots are far better at space exploration than humans.
Without the ability to do maintenance on the Hubble Space Telescope it would have been an epic fail from first light (due to how ineptly it was ground and then not properly tested before launch).
The subsequent repair missions have keep it in operation a lot longer than would have been possible otherwise (replacing failed gyros, failed electronics, orbit boosting), plus the ability to put in new technology instruments has to have been very valuable. And the ability to put in instruments for a limited time, i.e. ones that could be justified for a period between maintenance missions but not for the lifetime of the whole thing.
You're shifting your argument: you pointed out correctly that the Shutte is a boondoggle, claimed it provided "not one significant piece of science", and finished by saying "Robots are far better at space exploration than humans."
I pointed out just one example contradicting the last two points. Trying to apply the whole cost of the Shuttle program to just this one project is not to the point, nor is implying that we couldn't have done it in a manner that cost less and was safer.
I still say robots are far better than humans for space exploration. There was even a proposal for repairing the Hubble with them. It would have been better if they had designed it with this type of repair/upgrade mission in mind. But it is always easier for them to justify an incremental cost, along with the romantic notion of humans in space.
It probably wouldn't have worked for the last repair job, where they worked on things that had never been planned for repair (tiny screws and all that).
As an incremental cost, assuming you have a manned space program, you can't justify doing robotic repair due to the extra costs and limitations.
On the other hand the next big telescope project (http://en.wikipedia.org/wiki/James_Webb_Space_Telescope) will be non-repairable, but that sort of goes with its mission, which is to sit at the Earth-Sun L2 point. Design life of 5 years, they hope it'll make it to 10. Note that the Hubble has made it to 20 years and they expect it'll last at least another 4.
And I'll certainly agree with you that if you want to explore beyond Mars for now, do it with robots. And to put humans on the Moon or Mars, send robots first (as we did for the Moon and are doing for Mars).
On the other hand, if I wanted to thoroughly play with an asteroid, I would want to do it with a manned mission (after suitable earlier check-out by robots).
The subsequent repair missions have keep it in operation a lot longer than would have been possible otherwise (replacing failed gyros, failed electronics, orbit boosting), plus the ability to put in new technology instruments has to have been very valuable. And the ability to put in instruments for a limited time, i.e. ones that could be justified for a period between maintenance missions but not for the lifetime of the whole thing.
Robots have their place and so do men.