No evaluation of risk-managing the nation's infrastructure would be complete without an examination of air—that we breath, we fly through in aircraft—and the solid earth over which and onto which that air or craft returns. Exploring the air and outer space takes us full circle to the first of this series and the discussion of clean energy, if our earth is to survive, we must have fresh, clean and healthy air. 

But along with an unpolluted atmosphere, we must have the ability (since the early 20th century) to move safely through the air in something faster than a balloon—and, in the latter half of that century and the remainder of the current one—the ability to move through our solar system. It is all infrastructure, from the trees that convert carbon dioxide (CO²) to oxygen, and the scrubbers on power plant smoke stacks to the luxurious jetliners that fly us over the nation and to foreign lands, to the rocket ships that will one day carry us to Mars. All of it is expensive and at great risk, and that risk must be managed.

Man has always yearned to fly. Icarus didn't make it. Leonardo da Vinci designed a helicopter of sorts. As this column was taking shape, Felix Baumgartner, a sky-diving dare-devil, jumped out of a balloon up in the stratosphere and became the first human to break the sound barrier without a plane. I once met Chuck Yeager, who broke the sound barrier in a Bell X-15 Rocket. I also met one of the Apollo astronauts who'd been around—but not on—the moon. Even that had become so commonplace back in the 1970s that I have since forgotten his name, though it might have been Frank Borman.