Professor Reynolds is optimistic about NASA, and particularly about the prospects for space elevators and solar power satellites. I certainly agree with him that prizes are much more promising than NASA's past approaches, but it's discouraging to see the huge ratio between funds expended for traditional ways of doing business and those used for prizes. Still, at least the ratio is no longer infinite, as it has been in the past. If the prizes are successful, it should (at least in theory, though bureaucracies and politics can be perverse) make it easier for their proponents, like Brant Sponberg, to expand them in the future, and carve out a bigger budget for them.

As for the prospects for space elevators and SPS, I'm a little less sanguine. Successful prizes will move us closer, but it's still not clear that SPS will ever make sense compared to terrestrial alternatives (e.g., fusion, or nano-assembled solar-powered roads and clothes, or even nuclear if we can come up with more sensible reactor designs and attitudes toward waste). The inefficiency issues with power beaming are never going to go away, though advancing technology may mitigate them. I think that this will be a technology race, and it's not at all obvious to me what will ultimately win.

But because we can't know that, it also isn't to say that it's not an avenue that should be pursued, and perhaps even more vigorously than it has been. It's certainly been underfunded relative to those more conventional solutions. And if it is going to be pursued, as Glenn says, it's certainly better to do it via a technology prize route.

"The inefficiency issues with power beaming are never going to go away"

huh, from what i can recall, some japanese researchers have demonstrated microwave beaming over long distances with like 10% power loss quite some years ago already. What inefficiencies ?

They didn't demonstrate it over thousands of miles, but even with 90% efficiency from transmitter to rectenna (which is what I assume you mean), there are still the conversion inefficiencies of going from solar to DC, then DC to microwave. You have to make some really heroic assumptions for it to make sense relative to ground-based systems.