Watching the Discovery riding piggy-back aboard an equally ancient 747 over the Potomac River this morning was moving, especially after it was gone. It felt like seeing the last of something. NASA's space shuttle came from the same era as the Concorde and the SR-71, the Discovery's magnificently impractical new neighbors at the Udvar-Hazy Annex to the National Air and Space Museum.
Those three aircraft types were never sustainable -- always too costly and a bit too dangerous for even the diverse appetites of their clients. They were imperfect in all the same ways, and yet somehow also brilliant. For a commercial aircraft industry that now counts a 2% improvement as a revelation, and a 10% jump as a revolution, the Concorde, the SR-71 and the space shuttle are anachronisms of ambition. They come from a generation of explorers, not merely improvers. We may never see their many weaknesses ever again, but we will also never know their greatness -- and that's a shame.