No, I'm not saying that as an insult, but just to get your attention.

The "engineering perspective" too often confuses "this is possible" with "this is likely". Sure, we could have been much further in space now if we had really been properly motivated (for example, by asteroid belt equivalents of El Dorado or the Fountain of Youth). But the point I'm making is that economic and political constraints are much more effective than purely technical ones. And when we do initiate really big projects, the major obstacles are not the science, its the administrative and organizational ones.

Over a century ago, America built the Panama Canal, a massive multi-layered project comparable in scope and expense to an Orion interstellar probe today. We hardly broke a sweat doing it. It was an effort which was a welcome challenge to an aggressive and rambunctious new player on the world stage--an effort which had defeated France, a technical and economic giant of the 19th century. And France in the Gilded Age had lost its élan vital while we were just finding ours.

Maybe China could pull off a Ceres Canal project today. But I don't think we can. We blew our wad in the 1980s. You were there too, Robert, I'm sure you sensed it too.