A statement in this post by Clark Lindsey (and a further comment by Gary Hudson) on Hobbyspace reminded me why I’m somewhat uncomfortable with the term “sustainability” as it regards space exploration. I think the danger stems from how ambiguous the term can be. When you say “sustainable space development” to someone like Clark, Gary, or myself, it evokes concepts such as enabling a robust commercial spaceflight industry and acting as an anchor tenant for critical space infrastructure. But NASA uses “sustainability” in a completely different light. Under Griffinomics, ESAS is supposedly “sustainable” because Congress is unlikely to cut NASA’s manned spaceflight program much compared to what it’s getting right now, and therefore even if the architecture they pick is very expensive, it can still be perpetuated indefinitely off of bureaucratic inertia and parochial interests. Inspiring, huh?
A much better metric is the one given in Marburger’s speech: namely is our architecture being developed in such a way as to reduce the risk and cost of future operations? In manufacturing, there’s a concept called “continual improvement”. Basically the idea is that in a healthy system, you should be continually reducing scrap rate, increasing efficiency, decreasing lead time, etc. I think the idea of continual improvement is a good one for space development as well. A healthy and effective national space program would be one that is continually investing a sizable chunk of its public funds into creating or promoting the creation of new technologies, techniques, infrastructures, and markets that make future operations (manned and unmanned) less expensive, lower risk, higher payback etc.
To me the difference between the idea of continual improvement and Griffin’s idea of sustainability is the difference between innovation and inertia.