I don't think the space conquest spirit was ever lost. It seems to me that science-fiction is still largely dominated by space tales. To the extent that enthusiasm has declined, it is largely a product of the stagnation in the technology. There is only so much you can do with chemical rocket engines, and anything beyond LEO (or, at best, the moon) is going to be massively expensive with little real-world payoff. The technology that could take us beyond the moon and inspire people to believe in space travel again would require nuclear engines, which are limited by a strong taboo and international and national regulations against fission devices in orbit.
You'd think the safest place for nuclear engines would be in space... But of course, "nuclear" is a boo light.
This article http://www.huffingtonpost.com/andrew-kessler/why-you-should-be-more-interested-in-mars-than-the-olympics_b_1712462.html -- ok, I admit, I read Slashdot sometimes, no one is perfect ;) -- made me wonder why the awesomeness of space conquest stopped motivating people.
I remember the tales of my parents at the time of the Apollo landing, it was indeed instilling awe and wonder in the minds of people. It was followed by people like the Olympics or the football competitions are. And nowadays, NASA about to send a nuclear-powered rover to Mars, in a very delicate mission requiring the best of human engineering and scientific skills, and not in line in most media, most people not even aware of it? How did we fall that low?
Sure there was the Cold War. It definitely played a role, in the amount of resources invested by both sides in space conquest, and in the way the media broadcasted the news.
But here in France, a country that was mostly neutral during the Cold War (slightly west-aligned, but not part of NATO for most of the Cold War), the interest of people for space was not really partisan. People who were pro-USSR were amazed and cheering for the Appolo mission, people who were pro-USA were amazed and cheering for Gagarin. My brother and I played with (USSR) Sputnik as much as with (USA) space shuttles. We praised equally Neil Armstrong and Yuri Gagarin. I don't think the lack of Cold War explains it all.
So what happened to the space conquest spirit? How did it disappear? I notice a blank spot on my map (well, not totally blank, but still very fuzzy) of reality, do some of you have clues for how to fill it?