pft, planetary defence. What a crook of shit.
Ok, right now we haven't made it past the moon, and your thinking about extracting gold, silver, hydrogen from a moon millions of miles away? We have the biggest sorce of hydrogen right here in our own oceans. The earth is 75% water (i believe) and there is plenty of hydrogen floating around just waiting to be harnessed.
Also, there is enough gold floating around in the ocean (in little particles) that if all collected will equal 10-20 million lbs.
We can not do anything to protect our planet from a meteor. What are we going to do, an Arrmegedon style exicution? Hardly. All we will have to do is sit back and wait.
It can make us billions and billions, but right now it's probably costing us billions and billions.
NASA should be scraped. Its useless. Or atlest till we have the means to support it.