So that part of the industry has gone pretty well. Every day we use GPS and DirecTV and get the weather , and that sort of stuff. But human flight has just been totally crimped. The number of people going to space, and the missions they were doing, went down. The Space Shuttle was so much over budget that it just was impossible for us to really do any real exploration. That's a long-winded answer, but yes: There's every reason for people to be disappointed with where we are now, particularly with regard to human space flight.

JF: Why should people be excited about what lies ahead?

EA: In the next generation or two—say the next 30 to 60 years—there will be an irreversible human migration to a permanent space colony. Some people will tell you that this new colony will be on the moon, or an asteroid—in my opinion asteroids are a great place to go, but mostly for mining. I think the location is likely to be Mars. This Mars colony will start off with a few thousand people, and then it may grow over 100 years to a few million people, but it will be there permanently. That should be really exciting, to be alive during that stage of humanity's history.

JF: I have to ask—really? This will really happen?

EA: I really do believe it will. First of all, the key to making it happen is to reduce the cost of transportation into space. My colleague Elon Musk is aiming to get the cost of a flight to Mars down to half a million dollars a person. I think that even if it costs maybe a few million dollars a person to launch to Mars, a colony could be feasible. To me the question is, does it happen in the next 30 years, or does it happen in the next 60 to 70 years? There's no question it's going to happen in this century, and that's a pretty exciting thing.

JF: Apart from the cost of transport, what are the challenges in making that a reality? Are they cost and engineering challenges, or are they basic science problems?

EA: I think it's all about the economics. There is no technological or engineering challenge.

One key to making all this happen is that we need to use the resources of space to help us colonize space. It would have been pretty tough for the settlers who went to California if they'd had to bring every supply they would ever need along with them from the East Coast.

That's why Planetary Resources exists. The near-Earth asteroids, which are very, very close to the Earth, are filled with resources that would be useful for people wanting to go to Mars, or anywhere else in the solar system. They contain precious resources like water, rocket fuel, strategic metals. So first there needs to be a reduction in the cost of getting off the Earth's surface, and then there needs to be the ability to "live off the land" by using the resources in space.

JF: Again—really? To the general public, asteroid mining just has a fantastic-slash-wacky connotation. How practical is this?