It is an interesting (and also important) line. Generally, it is services that fall under the category of "public good" that are provided by government (in a ca

It is an interesting (and also important) line. Generally, it is services that fall under the category of "public good" that are provided by government (in a capitalist nation anyway). These are things that, by their nature, a) must be afforded to everyone for them to be effective, and/or b) for which there is no (or little) commercial incentive to produce. ... You know, I was going to write a lengthy explanation of what that means for your examples, but I'm late for work, and it's on Wikipedia: http://en.wikipedia.org/wiki/Public_good http://en.wikipedia.org/wiki/Public_good But suffice to say, there's no natural monopoly in space flight, and they're getting paid (by both the private and public sector) for their services, so space flight isn't a public good (anymore at least).