[mr_crankypants]

I honestly think that both of those are weak reasons. The first is a problem for other generations; on our own time scale we should focus on the problems that affect us on our own time scale. The second is just not compelling; space exploration is hardly the only endeavor that produces spinoff technology, and it's far from certain that it's the best or most productive way to do so.

There has only ever been one goal that has actually driven us to push our horizons further out into space, and I think it's the only one that really makes sense: We do it for the challenge and for the adventure.

As John F. Kennedy so famously put it, "We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills."

[cr0sh]

I honestly think the first one mentioned will become a "primary" reason as soon as the first largish "came from the direction of the sun" doomsday asteroid slams into us, and makes us rethink some of our priorities.

Assuming we survive the event - and assuming it isn't "The Killer Event".

You know - something largish that takes out 3-4 major cities, and we didn't see until much too late (like the near-space flyby we just had - though it was smaller).

Then again - we are talking human society here - so even that probably wouldn't cause us to sit up and think "you know, we're kinda sitting ducks here" and do something about it collectively.

I mean, look at the number of natural disasters that happen all over the world virtually every year in the same spots, yet do people really do anything to improve their chances next time, or do they say "it won't happen again next year" - and it doesn't, until a few years later when it does.

We're such a short sighted species for these kinds of things, and the dumb thing is, we know for absolute certainty that these events will happen, but because we don't know when, for some reason we decide to put off what we should be doing NOW, because when it happens, we'll either not survive the event (and everything we have ever done was all for naught - a footnote at best), or what remains won't have the means, perhaps ever, to rise to a similar level of technology to prevent it happening again.

[microtherion]

It's really hard to conceive of any disaster which would leave Earth less habitable than Mars.

[Vi0]

Why does propagating human genetics to a different planet/solar system give human existence meaning?

[dahdum]

> There has only ever been one goal that has actually driven us to push our horizons further out into space, and I think it's the only one that really makes sense: We do it for the challenge and for the adventure.

Individuals may think like that, but I think you're downplaying the Space Race. There was immense fear of the Soviet space domination, it was seen as an existential threat. If there could be only one goal driving us to those furthest horizons, it'd have to be conflict.

From the same speech as your quote:

"For the eyes of the world now look into space, to the moon and to the planets beyond, and we have vowed that we shall not see it governed by a hostile flag of conquest, but by a banner of freedom and peace. We have vowed that we shall not see space filled with weapons of mass destruction, but with instruments of knowledge and understanding:

JFK to Congress

"If we are to win the battle that is now going on around the world between freedom and tyranny, the dramatic achievements in space which occurred in recent weeks should have made clear to us all, as did the Sputnik in 1957, the impact of this adventure on the minds of men everywhere, who are attempting to make a determination of which road they should take. . . . Now it is time to take longer strides—time for a great new American enterprise—time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on Earth"

[nolok]

Challenge ? For the individual and its patrons, sure.

The country or company ? Its lured by the competition and wanting to be the one winning the prize.

But as a society ? When the inevitable "why fund space travel / fundamental physics / ..." question is asked ? Side gains is where it's at.