Prior to Apollo, the value of manned missions to space seemed self- evident, and a space station was considered an obvious first step as an orbiting laboratory, staging area, earth resources platform, zero-G manufacturing facility, and spacecraft service dock. Remember all those wonderful von Braun/Ley concepts, like the wheel in 2001? Robot probes were conceived as just that, quick recce missions to check out potential destinations.

But after decades of Mir, Skylab and ISS, I can't think of any of those ideas paying off, with the possible exception of the space medicine experience made possible by Mir, and that won't be utilized fully until we start having long manned missions. Instead of a foothold in space and a gateway to the solar system, the concept has just sucked up resources that could have been better utilized elsewhere. The benefits of manned missions (such as the servicing of Hubble) simply are overwhelmed by the costs needed to support people in that environment.

I am as supportive about manned missions as any space enthusiast, but I cannot think of anything we have done with then that has had anywhere near the return of our unmanned missions. Spacewalks and a few moon landings almost 40 years ago cannot compare with Hubble, Pioneer, Voyager, Mariner, Galileo, Landsat, Chandra, Hipparchos, IRAS, etc. I continue to support a manned space program, but as long as we can't afford to fund both generously, I think the cost-benefit analysis says clearly, go with the robots.