Those first steps on the moon 40 years ago in many ways marked the U.S. at a peak. By conquering the Moon, America vanquished its Cold War foe, the U.S.S.R., in the Space Race. It demonstrated the supremacy of U.S. science, engineering and manufacturing might. And it captured the imagination of people around the world.

Now as the U.S. marks the 40th anniversary of the Apollo 11 landing, many things are different. The Cold War is over, supplanted by the threat of terrorism. And with the nation mired in recession, there s a heated debate over the role of huge federal spending the kind of big government dollars that fueled Apollo s flights.

Buzz Aldrin, who walked on the moon with Neil Armstrong on that historic Apollo 11 flight, is a vocal advocate for expanding America s space ambitions. In his new book, Magnificent Desolation, Aldrin, 79, recalls the experience of flying on Apollo 11 and treading upon the moon s surface. He also discusses his struggles overcoming depression after the mission. Aldrin looks forward as well, outlining his vision for Mars exploration.

SmartMoney recently spoke with Aldrin about exploration, aerospace, America and taking a long view. Here are selected highlights:

SMARTMONEY.COM: WHAT WILL BE THE NEXT BIG MILESTONE IN SPACE EXPLORATION?

BUZZ ALDRIN: My big concern is to hopefully follow the Shuttle [program] with the early introduction of a U.S.-developed international lifting-body runway lander that will operate to and from low earth orbit. There is a wonderful economic opportunity for the country to take advantage of all the studies that have been done about bringing spacecraft back that are not anywhere near as large as the Shuttle, and returning them to a precision landing--landing on a runway.

There are two things that the public are not fully aware of and may not appreciate when they think of U.S. leadership. One is for us to have to rely on the Russian Soyuz spacecraft for five years or more to take our astronauts up to our over $100 billion investment in the space station. Also I think the American people and the people of the world appreciate the fact that once into the atmosphere, below the speed of sound, below Mach 1, all the landings of the Shuttle have been rather successful. To revert back to Mercury, Gemini and Apollo--to landing in the ocean or on the desert somewhere that s not controlled or precise--will be a disappointment to people .

I think that maybe it is a time for reevaluation [of focusing on a return to the moon]. Is that really what we want to do when we would be going there 50 years after we went there before? Is the purpose of human spaceflight to just entertain a new generation that comes along 50 years after? Or is it to make significant progress in our expansion of human capabilities, to begin to visit and settle much more hospitable places than the surface of the moon?

SM.COM: YOU HAVE TALKED ABOUT THE POTENTIAL FOR A SPACE RENAISSANCE. ECONOMICALLY WOULD THE MAIN BENEFICIARIES OF THAT BE BIG AEROSPACE COMPANIES? OR DO YOU SEE OTHER INDUSTRIES THAT WOULD ALSO BE TIED INTO THESE KINDS OF PROGRAMS?

ALDRIN: The beneficiaries I think would be the next generation of young people, and the nation as a whole as it attempts to hold on to the investments that we so satisfactorily and proudly made in the 60s and 70s to establish the United States as a significant leader in space activities, particularly human space activities. Right now the Russians have scheduled for October a mission called Phobos-Grunt. Phobos is a moon of Mars and what I consider to be the strategic location for expansion outward.

So you can say the aerospace companies would benefit. It is, I think, a little regrettable that there have been so many reductions in the number of companies through mergers and acquisitions. I think we ve been left with less innovation, competitiveness and specialization.

SM.COM: YOU MENTIONED YOUNG PEOPLE. DO YOU HAVE ANY THOUGHTS ON WHAT A YOUNG PERSON TODAY MIGHT STUDY, OR WHERE OPPORTUNITIES MIGHT BE? IN ENGINEERING, OBVIOUSLY, THERE ARE CONCERNS ABOUT MAKING SURE WE RE GETTING PEOPLE INTO THAT AREA OF EDUCATION.

ALDRIN: I am dismayed that our education system seems less competitive in comparison to the rest of the world. We ve identified the key areas, STEM science, technology, engineering and math.

We don t really make those professions attractive to people when there s such a focus on earning rather large sums of money that can come from other businesses. Having dedicated my life to serving my country and being in the military, and seeing what compensation the rest of the world, and the country thinks the military deserves for that, it s no wonder science, technology, engineering and math are not particularly attractive careers.

And it just doesn t spell well for our society and our country in the future. There is such a thing as planetary protection. When we have the ability to be able to prevent large objects from impacting the earth, I think we expect to be able to do something about that rather than just say it s not going to happen for 100 or 200 years.

SM.COM: PLANETARY PROTECTION, THAT S A SUBJECT THAT S SOMETIMES ALMOST MOCKED, AT LEAST POLITICALLY.

ALDRIN: Yeah, I certainly think so. [One person I ve been impressed with is] Stephen Hawking, to concern himself about the need for the human species to expand itself outward. I think it s an exciting thing to do. It s risky, it does require rethinking a lot of things.

The alternative is to have a serious discussion and debate: Do we intend to permanently settle or not? And if we re not ready to begin to take that on, at least in an inquiring way, then maybe we don t even do anything or shouldn t do anything.

Obviously, I ve been doing an awful lot of thinking for the last 40 years about the directions we really ought to go, and what the return will be. To me, there clearly is a pathway that leads to human habitation and settlement of Mars, a much more attractive location than anywhere else.

Certainly I think history will look kindly on the world leader much like Isabella, Queen Isabella of Spain when she allowed Christopher Columbus to set sail who enables creatures from the Earth to be settlers on another object in the solar system. To me, that s a big deal, and I think we re on the threshold of beginning to want to think about that.

SM.COM: THE LONG VIEW THAT YOU RE DESCRIBING ISN T ALWAYS A BIG PART OF PUBLIC DISCOURSE THESE DAYS.

ALDRIN: I think it can very well be the downfall of our particular society. If you phrase it in the terms What s in it for me right now , I will tell you that s why we have problems right now. Because that s been the focus.

If that s a characteristic of our overall system then maybe some modification needs to take place. I m not sure I know what it is. But that s not my field. My area of expertise may be just looking ahead as to how to come up with better utilization of transportation options to get to different places in space. I think we could fly by comets, station-keep with asteroids, for much less of a financial investment sooner than we could land our people on the surface of the moon again. To me, that is opening up a pathway that excites people and provides some interest that was similar to their interest in the Mercury, Gemini and Apollo programs.

SM.COM: WHAT S NEXT ON YOUR PERSONAL AGENDA? IS IT PRIMARILY TRYING TO DRAW ATTENTION TO THESE ISSUES?

ALDRIN: I ve invested a good bit in looking into the future. . That s my task, to try to stimulate a little outside, different thinking.