Joe Carroll is giving a talk on some long-shot “wild cards” that could have a high payoff. One of them is aerosnatch of first stages, which could simplify launch system design by eliminating the need for flyback, and has such a high payoff in performance, that he suggests we understand it better before making any decisions on heavy-lift design, because it may set an upper limit on economical launch vehicle size.
Another is recycling aluminum on orbit, as a first step toward processing true extraterrestrial materials. He points out the bizarre (and typical of a government) situation in which everyone agrees that orbital debris is a problem, but there is no budget for it anywhere in the federal government. Also discussing slings and elevators, propounding the advantages of the former over the latter. For people to an from LEO, elevators, but for a lot of payload beyond, slings are the way to go. Makes an analogy of going from ships to railroads. Rockets are the ships, slings are the railroads (the latter requires an up-front infrastructure, and is limited in destination, but very efficient once in place). Thinks that the first sling will be at 51.6 inclination, second at zero.