"If, as a result [of deflecting or otherwise rendering harmless a comet, meteor, or asteroid headed for Earth] one city is left undestroyed...
...then wouldn't all the money we have ever spent on space exploration be worth it for that one reason alone?"
-Isaac Asimov (1920-1992)
Not if that same money could have been used to save several cities worth of people from the ravages of hunger or disease.. There's always the conundrum of opportunity cost. With current technology, there's not any benefit to be gained from manned space exploration, except political. I fully expect China will be the next country to send a man to the moon, but the gains will all be political, not scientific.
That said, I wouldn't mind sending some settlers to colonize Mars, but the preliminary exploration, and even a good deal of the Mars base construction should be accomplished by robot.
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