I thought I'd learned a long time ago that if you're going to write in public, you need to start with a large backlog of already written pieces, so that when a dry spell comes (christmas vacation or whatnot), you can post the prewritten bits and not lose your audience. Well, you have to remember to post those prewritten bits.
I just read Giving future human space explorers the credit they're due. I think it nicely, if accidentally, summarizes the pitiful reasoning behind manned space exploration.
Mr. Kendall's main point seems to be that humans can cover more difficult terrain, and more of it, than robots. Fine, we'll build a rover with legs. This is orders of magnitude cheaper than sending people to Mars. Note that people on Mars are going to need vehicles to get any great distance anyway, so I suspect there is no real advantage for people here.
The Mars rovers have driven only kilometers because they are small, low power vehicles. If we want to spring for more payload for a faster vehicle, we can do that without also spending orders of magnitude more for a person to ride on that vehicle.
Second point: people can be more detailed than robots with the same instruments. Given the vastly superior stay-time of robots, I find this unbelievable. His point about people staying 500+ days on the Martian surface presumes a very expensive mission.
Third point: Excavating partially buried rock, drilling hundreds of meters... These seem like things not done by people but by their equipment, and are an excellent argument for robots.
Fourth point: repairing broken parts, creating new tools. How? With what? In a machine shop? How much will that weigh?
Fifth point: pilots can step in if mission control miscalculates. No way. No pilot is going to override a reentry burn successfully. What data would he base his intervention on, that mission control does not already have?
Sixth point: cultural importance, human triumph. Now we're back to "footprints in the dust". This is bogus. Footprints are symbolically important when they are the first footprints of many. When we have a reason to put people on Mars, the first footprints there will be (temporary, due to wind) symbols of our purpose there. What are the lunar footprints symbols of? Peace?
Seventh point: educational importance. How do we make Mars interesting enough for a fourth grader to pay attention? Step 1: put in a sense of scale by placing a person in the picture. This helps, but it's not worth the money. I have a better suggestion: concentrate on movie cameras that take pictures that people care about. Make sure the mission definition team has an experienced, professional nature photographer with sufficient clout to overrule science goals if necessary and ensure that the mission returns great TV.
I think we're missing movies of robots in action. Taking pictures of the exploration itself is what communicates the triumph to the taxpayers footing the bill. We need movies of rovers drilling rock and driving around. We need movies of assembly robots piecing together large orbiting telescopes. We need movies of Cassini cruising through the rings.
Movies aren't usually included because the bandwidth required is appalling, and wouuld swamp the science returned. This is not a problem anymore. The cameras and recording system can be lightweight and solid state. They should be standard NTSC resolution, and use compression like any non-science TV show uses, as the point isn't to enable some scientist to make verifiable conclusions by closely examining the pixels. Finally, the cameras can shoot dozens of hours of footage, store it locally in a few hundred gigabytes of flash memory (lightweight and cheap nowadays), and the probe can send back a tiny fraction of that selected by a movie director.
The other problem with movies is that there hasn't usually been a vantage point from which to film the robot. But this need not be the case either. The Deep Impact mission actually had two probes. The one that survived could have sent back a nice high-res, slow-motion movie of the moment of impact in the months after the mission was over. The Mars rovers all had landing vehicles that could have shot movies of them leaving the lander. Heck, I think it would be reasonable for the rovers to cart around a monopod with a remote camera on it. Find a nice rock, stick the monopod nearby, then drive over and look at the rock while being filmed from the monopod. When done, pick up the monopod and drive on.