I agree, Space Exploration needs to be one of our major priorities especially with the Chinese getting into the game.
Really, the problem here is that the US hasn't been nationalistic enough, and all of the left wing stuff about how "oh the Ruskies and Chinese are our friends" has detracted from the reality of the situation and how far behind we've been getting. To a liberal, why does it matter if we give Russia space if they are our bestest buddies in the world?
Given the things China has been doing to our satellites (do a search for China, Satellite, Lasers, it's been an issue since like 2006) I think one way to justify the spending would be to do what few people have wanted to support before... and fold The Space Program into the military officially, and task the military with coming up with obtaining domination over space as well as land, sea, and air. While boats, Jets, and Tanks are all important, I think folding the money being used to develop some of that stuff into spacecraft could achieve the same or better results.
The way I look at it is that being #1 in defense spending, but having pathetic funding for The Space Program, if we combined the two NASA and the Air Force could more officially pool their resources towards developing something like Air/Space superiority craft, rather than just pumping the money into new fighter craft or whatever. If we could build say a space shuttle that is also a stealth bomber armed with WMD, while keeping most rival space programs landlocked without our direct approval... well guess what, that guarantees American primacy for a long time to come. Even if we never actually use it, if we're ruthless enough we won't have to.
The way I see things is that if we don't develop that kind of tech someone like The Chinese are going to, and from that point on guess whose mercy we'd be at when it comes time to exploit the astroid belts for minerals, or put science stations on Mars? Yeaaah, not a pleasant thought is it?
Basically I agree with our Astronauts more or less, but in their case they are short on solutions or direct justification. Me, I have no real problem with saying that The Chinese and Russians are NOT our friends, and that like it or not we're in a very real space race again, one that already has military aspects to it, yet we're refusing to even get off the starting block due to naive politics and being overly moral.