Astrobiology Magazine (AM) : I recently read a book called "Moondust," in which many of the astronauts who'd walked on the moon, including yourself, were interviewed. The author noted that the number one question asked of lunar astronauts is, "What was it like to walk on the moon?"

Harrison Schmitt (HS) : You know what the number two question is? "What was it like to walk on the moon?" You can never answer that question to anyone's satisfaction.

AM: That's what it said in the book -- no one felt they could express it adequately.

HS: Well, you can't. Being there is an essential ingredient. It's the same as trying to describe to someone what it's like to stand on the rim of the Grand Canyon. Or to have your first child. Any meaningful event that you've had in your life is probably that kind of experience. It has a personal meaning, and it will be different for every individual.

But sometimes people just want a description of what it was like -- the black sky, the brilliantly illuminated slopes of the mountains, the bright sun, and then our Earth as a big blue marble hanging over one of the mountains. The physical feeling of walking on the moon is like walking on a giant trampoline, to some degree.

AM: That brings me to a question about the human physiological limitations in the moon environment, which we'll have to overcome if we want to develop a permanent base there. For instance, spacesuits are not very practical for daily use. You've said that the pressurized gloves of a spacesuit quickly exhaust the muscles of your forearms when you use them.

HS: Right. It's like squeezing a tennis ball continuously. But I think those limitations are temporary. I'm sure all of them have technological solutions. The broader questions of physiological adaptation also must be addressed, first by definitive research and then by specific countermeasures. And also, potentially, there are pharmaceutical solutions. We just haven't worked hard enough over the past 40 years, frankly, to develop countermeasures to the adverse consequences of space adaptation.

AM: The space suit has evolved over that time.

HS: But it's still basically the same concept. Although the suits are still being used on the shuttle and the space station, we have to get away from what we're doing now and start on a clean slate. Our technology base today is better than it was 40 years ago, so I hope we can stimulate some new thinking with this "Moon, Mars and Beyond" initiative.

AM: I read one account of an astronaut who strayed too far during a spacewalk, and the physical effort of getting back was so exhausting he almost didn't make it. And then to think of the effort people will expend on the moon, having to struggle in similar ways every day�

HS: Use of the suits takes physical strength that even an extremely well-conditioned person sometimes just doesn't have. Another problem right now, at least in the US program, is the suits are standard sizes. And the smallest suit is still too big for some people who are in the astronaut program, particularly for some of the women. If that doesn't change, they will never be able to experience EVA. But why do the suits have to be like that? We should see if we can come up with a better solution.

AM: As a geologist on the moon, did you use a rock hammer?

HS: I did a little, but not a lot. In our crew, it was principally the tool that Gene Cernan used. Even though I was responsible for the design of a lot of the equipment, or at least monitoring the design, the hammer handle was a little too big for my hand. I found that I could do almost everything I needed to do and get all the samples I wanted with a scoop. When I needed to break rocks, Gene broke them, although occasionally I had to show him how to do it.

The Apollo pilot astronauts hadn't grown up doing geological field work, and they often would try to break a rock by hitting it in the middle rather than on the edge, where it chips off very easily. For some reason, even though we'd spent several days in the field training them in geology, in the final analysis they just wanted to beat on the rock. That's not the best reason to take a geologist to the moon, but it's one of the reasons.

AM: Also because a geologist can recognize which rocks are the most scientifically interesting.

HS: That's right �- geologists have a life history of observational science. Now, in fairness, test pilots have their own history of observational science. They were all good observers, and we took advantage of that in the training. But just as I wouldn't try to compete with them as test pilots because they had 10 to 15 years advantage on me in that field, I had a similar advantage on them in field geology. And that's why you want to take professional people into space, to the moon, and to Mars �- you want people who have life experience that's relevant to what we need to do. So we need to always be thinking of how to mix and match crews so that we have the maximum necessary experience base. And then you cross-train between the various disciplines.

AM: That's one thing about astrobiology -- it's so interdisciplinary. When you give talks at astrobiology meetings, do you get a sense that your audience could likely contain the next people who will be going to the moon and Mars?

HS: Some of them are the right generation. I hope that they have a chance to join up, and that the selection process gives them the opportunity. The selection process doesn't need to be nearly as rigid as it was physically; it's going to be based more on intellectual competition than physical competition.

AM: I've read that when the space program first started, scientists really didn't know how the human body would respond to being in space.

HS: That was partly why the selection process was so hard. They were conservative because of the uncertainty about human physiology in space. And also, the Apollo spacecraft required everybody to be a pilot. There already was a physiological envelope you had to fit into in order to be a pilot -- your eyes, and heart, and things like that. And since all of the scientists had to become pilots, we had to pass through that filter as well.

AM: But you don't think physical qualifications are going to be an issue for future space travel?

HS: It already isn't an issue. As soon as the shuttle came along, it was no longer as much a concern.

AM: But that's low Earth orbit, versus going to the moon.

HS: It depends on the size of the spacecraft, and how the technology is done. If you have a spacecraft that you want to land on the moon and it can handle, say, four people, then two of them can be pilots �- you need a pilot and co-pilot �- and the other two can be whatever discipline is appropriate. Two field geologists would obviously be a good thing.

(AM): NASA is currently designing habitation modules for future settlements on the moon. What are your thoughts about these plans?

(HS): The current NASA approach is that the lunar base will be like Antarctica, in that people will rotate out -- they'll go there and come back. But when you look at it from a commercial point of view, where you are mining the moon for energy resources, that's a very costly approach. The least costly approach is to have people stay to live. Then you don't bear the cost of bringing them back. It's the fastest way to develop a settlement, and to have the human species moving out into space.

I think there are no disadvantages to that approach. There are plenty of people who'll say, "Yeah, I'll go there to live." There always have been and I don't think young people today are any different. The exploring will continue. Part of it's been done by Apollo, but the next people will be going as pioneers, and I think they'll go to stay. NASA should approach it that way, but I haven't convinced them yet.

AM: I think NASA plans to take it more gradually, starting with a week-long stay, then a month-long stay, and continuing from there.

HS: Maybe in order to get started you have a mission or two where you go there and come back. But we have large rockets, we know how to build spacecraft, and we certainly know how to live on the moon. I think you can form a settlement right away. Now, I say permanent settlers, but as soon as you have the capability to go to the moon, having paid for it with capital investment in energy, you're going to have a tourism capability too, at relatively low cost. And so the people on the moon can take a vacation on Earth. I discuss these considerations extensively in my book, "Return to the Moon."

AM: But then don't you have to worry about the gravity readjustment of coming back to Earth after being on the moon for a long time?

HS: I think we'll eventually know how to fix that. The one thing that we don't know, and may turn out to be true, is that one single strategy may be enough. It may reset all the body systems that would otherwise be demineralizing bone and breaking down muscle.

AM: When Astrobiology Magazine held a terraforming debate about Mars, the view was expressed that, after a few generations on Mars, the human body would adapt so much to the reduced martian gravity that settlers would be unable to come back to Earth.

HS: No. Over a few tens of thousands of years, maybe, if there's a selection for it.

AM: But the immediate adaptation to the environment, such as how gravity affects the way bones develop�

HS: Well, maybe. But again, there are ways to counter that, such as exercise. But one of the things we don't know is how much gravity the human body needs. We haven't done that kind of research in orbit. Hopefully we'll figure out a way to fly the Japanese centrifuge so we can create artificial gravity and find out what the breakpoint is. Is it one-sixth Earth's gravity? Three-eights? So it may not to be an issue on Mars. On the other hand, if it turns out to be an issue, then you look at ways of stimulating bone deposition.

As I get older, if I don't keep exercising and stressing my bones, I'm going to lose bone mass. But that's true of anybody. If you were on bed rest for two weeks, you would come out with basically the same thing as if you were weightless for two weeks. There's so much that has been going on in biomedical research here on Earth that has yet to make its way into space, so I think we're going to figure all this out. There is a tendency to try to scare ourselves, and some of that is because it's a way to get funding. Or maybe we've had too much time to think, and we just need to get operational again.

AM: That's an interesting perspective. There is that aversion to risk. I think people would really take it hard if there was a "Jonestown" on the moon or Mars. I've heard some scientists express the fear that if such a tragedy occurred, the exploration program would die right there.

HS: The chances of that happening are higher if it's government funded than if it's investor funded. There are a lot of other motivations to maintain an investor-funded settlement, or to reconstitute a settlement. That happened in the early exploration of the United States. Settlements disappeared, and yet they still kept coming back.

AM: Because they were looking for great wealth, and there was competition with the other nations.

HS: It wasn't entirely that. Plymouth was a private enterprise. There are all sorts of motivations that drive people to explore. One of the primary motivations that ultimately settled the United States was the desire to be free of constraints. People went out to the frontier because they didn't want to be constrained by society.

The initial settlements on the moon will be constrained. We keep thinking we're going to control them, but once they reach a certain critical mass, they'll do what the original Americans did. "Taxation without representation? Forget it! And if you want your energy resources, then you're going to leave us alone!"

AM: There'll be a nation of the moon.

HS: Yes. It's with malice aforethought that I indicate a new birth of freedom, because once you start settling the moon and Mars, there's going to be a whole new thinking about the constraints that Earth imposes.

AM: Did you ever read the Kim Stanley Robinson book series, Red Mars, Blue Mars, and Green Mars? Because he discusses a lot of the societal changes you're talking about.

HS: I read parts of them. I had my students look at them for a course I was teaching at the University of Wisconson-Madison. I'm not a terraformer, though.

AM: So you want Mars left alone?

HS: Yes. I don't think you need to do it in order to establish human settlements. Plus, as soon as you terraform, you start to deplete resources very fast because Mars doesn't protect itself like the Earth does. It doesn't have an ionosphere, which on Earth protects the surface from solar radiation. Also, Mars is too small to hold onto much of an atmosphere.

We can develop the technology to live there, so why change the planet? We can inflate shelters and cover them with the Mars equivalent of the regolith. Mars doesn't have a lunar-style regolith, but it has a very fine dust. You're just going to have to get used to having a lot of sulfates around.

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