There's an old saying in the space community: 'If God wanted us to be a spacefaring species, he would have given us a moon'.

If humans one day become extinct from a catastrophic collision, there would be no greater tragedy in the history of life in the universe. Not because we lacked the brain power to protect ourselves but because we lacked the foresight. The dominant species that replaces us in post-apocalyptic Earth just might wonder, as they gaze upon our mounted skeletons in their natural history museums, why large headed Homo sapiens fared no better than the proverbially peabrained dinosaurs.

We went to the moon and discovered earth

I agree that we should go back to the moon and on to Mars. We should treat all objects in the solar system, including comets and asteroids, as exploration targets.

There are countless space activities that would be no less exciting than the moon missions were, I have no doubt. The search for life on Mars, for example.