Dr. Zubrin: As I see it, there are three reasons why Mars should be the goal of our space program: and in short, it’s because Mars is where the science is, it’s where the challenge is, and it’s where the future is. It’s where the science is because Mars was once a warm and wet planet, it had liquid water on its surface for more than a billion years, which was about 5 times as long as it took life to appear on Earth after there was liquid water on here, so if the theory is correct that life is a natural development from chemistry, where if you have liquid water, various elements and enough time, life should have appeared on Mars even if it subsequently went extinct, and if we can go to Mars and find fossils of past life, we would have proven that the development of life is a general phenomenon in the universe. Or if go to Mars and find plenty of evidence of past bodies of water but no evidence of fossils or the development of life, then we can say that the development of life from chemistry is not sort of a natural process that occurs with high probability but includes some freak chance and we could be alone in the universe. Furthermore if we can go to Mars and drill, because there’s liquid water underground on Mars, reach the ground water, there could be life there now. And if we can get hold of that and look at it and examine its biological structure and biochemistry we could find out if life as it exists on Mars is the same as Earth life because all Earth life at the biochemical level is the same—we all use the same amino acids, the same method of replicating and transmitting information, RNA and DNA, all that---is that what life has to be, or could life be very different from that? Are we what life is, or are we just one example drawn from a much vaster tapestry of possibilities? This is real science, this is fundamental questions that thinking men and women wondered about for thousands of years, the role of life in the universe. This is very different from going to the moon and dating craters in order to produce enough data to get a credible paper to publish in the journal of geophysical research and get tenure, okay? This is you know hypothesis driven, critical science. This is the real thing. Second, the challenge. I think societies are like individuals, we grow when we challenge ourselves, we stagnate when we do not. A humans to Mars program would be tremendously bracing challenge for our society, it would be tremendously productive particularly amount youth. Humans to Mars program would say to every kid in school today, “Learn your science and you could be an explorer of a new world.” We’d get millions of scientists, engineers, and inventors, technological entrepreneurs, doctors, medical researchers out of that, and the intellectual capital from that would enormously benefit us. It would dwarf the cost of the program. And then finally, it’s the future. Mars is the closest planet that has on it all the resources needed to support life and therefore civilization. If we do what we can do in our time—we establish that little Plymouth rock settlement on Mars—then 500 years from now, there’ll be new branches of human civilization on Mars and I believe throughout nearby interstellar space, but you know, look: I ask any American what happened in 1492? They’ll tell me, “Well Columbus sailed in 1492,” and that is correct, he did. But that is not the only thing that happened in 1492. In 1492, England and France signed a peace treaty. In 1492, the Borgias took over the papacy. In 1492, Lorenzo De’Medici, the richest man in the world, died. Okay? A lot of things happened, if there had been newspapers in 1492, which there weren’t, but if there had, those would have been the headlines, not this Italian weaver’s son taking a bunch of ships and sailing off to nowhere, okay? But Columbus is what we remember, not the Borgias taking over the papacy. Well, 500 years from now, people are not going to remember which faction came out on top in Iraq, or Syria, or whatever, and who was in and who was out and you know….but they will remember what we do to make their civilization possible, okay? So this is the most important thing we could do, the most important thing we could do in this time, and if you have it in your power to do something great and important and wonderful, then you should.
Robert Zubrin - Wikipedia