Space Exploration

So what does everyone think of it? Months ago I had a Facebook status questioning its worth. Unfortunately FB statii are not searchable and I can't be bothered trawling through yonks worth of statii to find it.
So... A program on the other night where James May got ridiculously excited about Space Exploration reminded me of it.

What IS its value?
All of this is framed by the fact I think exploration for exploration's sake is worthwhile. Surely, or you and I would be ignorant about a lot of the planet we live on.

But on the other side, there is still some of this planet to be explored, particularly its deep oceans. New species of life are being found in all sorts of envronments to this day. Surely tat is more relevant than anything in space?

On the other side again, we didn't know that we would find little of use in space until we went there. Rocks and dust.
We now know what the composition of the moon and Jupiter is. Great! Is it useful to us? I can't see how other than to make us sure we probably don't want to live there.
I'm not the best informed but it seems most of what has been useful from space exploration has been peripheral such as the invention of pens that write in zero gravity. Much better than the Russian's solutions of pencils. Though who knows - if they had developed Zero G pens, they may be a world superpower right now.
Also, discoveries in the area of particle physics that is useful up to a point, then very theoretical and not so useful... but potentially useful. Maybe. Or just interesting. Is knowledge for knowledge's sake valid? Or only if it's applicable practically?
The exploration of space has cost billions! Those billions could be spent right here on helping Earth's citizens much more directly. The obvious ones are things like finding cures for cancer, more efficient fuels or more efficient ways of using existing ones, ending poverty etc... but any number of causes could be helped by turning this wodge of funding directly on helping people. I'm not naive enough to think it WOULD be, but it COULD be. Then again, til we look, we don't know that the cure for cancer, a remarkably effiecient and eco-friendly fuel and end to poverty won't be found on Neptune or beyond... but what are the chances? Maybe the answer to all these three lies in the particle physics, providing the proof of the God Particle doesn't implode Earth in th process.
The push to explore has led to developments in propulsion and heat-proofing and other things all useful on Earth. But the difference from the days of the great explorers exploring Earth seems to be that we are now developing these technologies solely to go and explore against all odds, rather than the technology developing naturally from a necessity to travel for survival and then getting curious. We are now spending vast amounts on overcoming ridiculous odds. We are sending people to places where they would naturally asphyxiate, burn, freeze, and explode simultaneously and instantly. Do we need to? Or are there more worthwhile endeavours?

I want to know what y'all think?