I don't get the fascination with manned space flight. To me it's such an obvious waste of money. I find the robots we send to space a million times more fascinating.
It is about making a future for uncountable trillions of (post-)human beings, instead of the few measly billion our single planet can support.
It is about blossoming new cultures in far off places, instead of stagnation and unity.
It is about expanding the human economy to include effectively limitless new land and resources instead of fighting the same zero sum game.
It is about providing a cosmic lifeboat such that one single catastrophe doesn't wipe out the human race or all life on Earth.
Sorry, I think the burden of proof is on those who say the above is meaningless.
For confirmation just look to NASA's vision, mission, and strategic goal statements, and the report of every blue ribbon commission to have looked at NASA over the past three decades.
[1] https://www.youtube.com/watch?v=WGgtsn9SCkg (in French)
Spaceflight has contributed very, very little technology to earth. The reality is that anything we fly into space is already generations behind the equivalent earth technology.
Put it another way: What were the obvious benefits of the Apollo program?
http://en.wikipedia.org/wiki/NASA_spin-off_technologies
What were the direct benefits of Amundsen's expedition to the south pole? Is exploration a waist even if its results are less than stellar? I would say that by its nature, exploration is a hard thing to waste money on. Necessity is the mother of invention and nothing provides necessity like pushing the envelope. For example, look at the picture that accompanies this article. http://en.wikipedia.org/wiki/Genetic_algorithm
You can't simply say that all exploration gives value for money. With finite resources, we have to direct spending to where it will result in the most benefit. Funding of human spaceflight means that there's less funding available elsewhere. I'm not familiar with who funded Amundsen's expedition, but I'd imagine that it cost a lot less than the trip to the moon did.
There has been innovative developments in the space industry. Some of those spin-off technologies are definitely valid (although the question of whether the return they provide given the absolutely huge R&D budget is worth it) but others are less so. Freeze drying was apparently initially developed in 1938, long before the space program. I find it hard to believe that, in the absence of a space program, nobody would have invented the portable vacuum cleaner.
There are benefits from a space program. Government R&D, when spent well, has a huge impact on technological progress (just look at the absolutely incredible technological step change that wars bring). What I think needs to end is the absolute idolisation of the space program. It's an investment, and one which has often shown a poor return.
There are many reasons for that. For one thing, the environment that it has to operate in is...poor. The "best of breed", most modern technology typically doesn't like that sort of thing. The technology in your automobile's engine compartment is also typically generations behind, as is the stuff in your toaster (for slightly different reasons).
Second, the technology of the manned program (and the same argument applies to a lesser extent to the unmanned program) is "man-rated"---it's specifically tested to ensure that it won't fail in some spectacular fashion and kill everyone. That is expensive, and takes a lot of time. One way to make that cheaper is to maintain a pedigree; what you fly today flew yesterday, or is based on something that you flew yesterday.
And then, of course, at current effort levels, building a new launch platform is mostly a non-starter. So, you might as well go with what's already working.
"Spaceflight has contributed very, very little technology to earth."
You need to keep a distinction in mind: manned vs unmanned. Unmanned flights are plenty competitive in terms of basic research.
Further, many people, before the Internet Boom, got into science and technology because of the manned spaceflight program. To an extent, some of those that went into spaceflight-specific programs were lied to. But still, they have made some contributions, somewhere.
While the knowledge will hopefully be useful in the future, and we can spread humanity to more than one relatively small, condensed point, at present it's not really helping us, and was pretty much a waste of money. At present.