Earlier this month, while the Space Shuttle was still in orbit, Idle Words posted a long article on the history and controversy over the Shuttle entitled A Rocket To Nowhere. Although it is definitely a somewhat biased view of the Shuttle's missions and capabilities, I agree with a lot of the points made in the article. Here are a few notable ones:

Sinking half the NASA budget into the Shuttle and ISS precludes the possibility of doing truly groundbreaking work on space flight. As the orbiters age, their upkeep and safety requirements are becoming an expensive antiquarian exercise, forcing engineers to spend their ingenuity repairing obsolete components and devising expensive maintenance techniques for sclerotic spacecraft, rather than applying their lessons to a new generation of rockets. The retardant effect the Shuttle has had on technology (like the two decades long freeze in expendable rocket development) outweighs any of its modest initial benefits to materials science, aerodynamics, and rocket design.
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For all the talk of building a culture of safety, no one has pointed out the inherent contradiction in requiring that a program justified on irrational grounds be run in a rational manner. In an atmosphere where special pleading and wishful thinking about the benefits of manned flights to low earth orbit are not just tolerated, but required of astronauts and engineers, how can one demand complete integrity and intellectual honesty on safety of flight issues? It makes no sense to expect NASA to maintain a standard of intellectual rigor in operations that it can magically ignore when it comes to policy and planning.

I disagree with the assertion that most of the Shuttles' missions (summary here; details starting with STS-1 here) are worthless demonstrations of "ants sortings screws in space" (a Simpsons quote, not the article's), as the program on the whole has developed and refined many technologies that have yielded practical breakthroughs and benefits. Still, I have to admit that boondoggles like John Glenn's return to space are highlights of some of the program's more wasteful moments.

There is no question that the Space Shuttle program is the jewel in NASA's crown, and a lot of prestige would be lost if it were prematurely retired. As much as I would like to see it continue to support the operation of the International Space Station (and to keep alive the long shot of rescuing the Hubble Space Telescope), I think it's time for NASA to take a long, hard look at whether its funds are best spent just keeping up with an obsolete design and "trying to keep its participants alive" rather than truly innovating and developing the next generation platform for space exploration.