NASA’s chief scientists historically have been drawn from the nation’s ranks of astrophysicists and astronauts. “I guess I’m a trial balloon of a new breed: a planetary person as chief scientist,” says planetary geologist Jim Garvin, who assumed the post in October 2004. More likely, Garvin’s appointment reflects the agency’s reinvigorated emphasis on exploration of the Moon and Mars. Garvin comes to the position with a detailed background in Mars science and a reputation as a precise speaker.

 He is as comfortable in the mainstream — he has already appeared on Late Night With David Letterman to talk about NASA’s Spirit and Opportunity rovers — as he is among speaking among his colleagues.

 In 1999, Garvin chaired the agency’s Next Decade Planning Team, which developed many of the ideas that were embraced in President George W. Bush’s Vision for Space Exploration announced in 2004.

 In 2000, he was assigned to help overhaul the agency’s Mars exploration agenda following the loss of the Mars Polar Lander and the Mars Climate Orbiter. He was also an early advocate of sending twin rovers to Mars.

Garvin spoke by telephone recently with Space News correspondent Ben Iannotta.

The president’s Vision for Space Exploration appears on just about every NASA Web page. Almost every scientist involved with NASA I’ve spoken to refers to it. Why is that document so important?

This is the first time in a generation we’ve had a presidential space policy directive that gives us the focusing power for our agenda. The directive says, advance U.S. scientific leadership in space. That gives us the ability to emphasize programs and make choices and decisions.

For NASA, being a discretionary agency, having that focusing power like we had during Apollo is very advantageous.

When it comes to a choice to invest in X, which would eventually be good to help us to do Y in space, we can now put a test filter in there that says: if X will [help] get us to the Moon and Mars [in a better way] — and advance our leadership — then we can do that.

If it doesn’t, so what?

The bottom line is, it’s a wonderful lens for focusing our decision making.

What’s a good snapshot version of the vision’s goals?

It’s important to go to Mars before we become too Earth centric. The Moon gives us the practice ground and the proving ground to learn how to do things in this new partnership with people and machines that we didn’t have last time.

We’re building the Space Interferometry Mission to extend our apertures and get a clearer view beyond our solar system. We’re searching for life beyond Earth, and the origins of life on Earth. We will use Earth as a window on the universe, and of course, other biology, if there is any.

Why is Mars so important?

If we can understand the climate history of Mars that could help us understand Earth. On Earth, those dynamics may be murky, but on Mars they may be clearer. It’s like looking at a control experiment for Earth.

Our planet is a complicated, interconnected, dynamic system. We’re now making the measurements to allow our predictive capabilities for Earth to be better in terms of predicting weather and climate, and all the things that go with that, such as sea-level fluctuations, and atmospheric chemistry impacts that may or may not be anthropogenic.

How important is the role of human beings in exploring Mars?

That’s a common misnomer. People are exploring Mars right now through a pair of twin rovers. We extend ourselves through our machines. The idea that there’s this dichotomy between robotic and human exploration is a false dichotomy.

That said, today after 420 days of exploring Mars with the rovers, we’ve generated 75,000 scientific photographs and driven these rovers four or five miles.

On a human mission, even a short one of 30 or 40 days on the surface, we could do extravehicular activities each day that would be the equivalent of a five-mile rover mission.

Machines are needed to open these places so we can insert people. People will go to the hot spots, the sexy spots on Mars and the Moon.

Do NASA scientists, and those funded by NASA, have full freedom to study some of the hot-button issues of today, like global warming, without the intrusion of politics?

Absolutely. Intellectual freedom is a fundamental tenet of our policy that I’m responsible for. NASA competes all its environmental research. Now, if a scientist says Moon rocks are made of Swiss cheese instead of silicates, that research might not be funded.

That said, we can’t control what government leaders and industries choose to do. In the same way, we can’t control what a NASA-funded scientist chooses to say in a public forum about scientific results.

Polls show that many or even most Americans believe in the literal Biblical story of creation. Is there a role for NASA in answering those fundamental questions?

There’s a science role but it’s up to individuals to choose their own methods of belief.

As a NASA scientist, respecting the scientific method, I believe in asking questions and looking for answers. To me, the beauty of the universe is the greatest mystery. Maybe that’s at least one person’s embodiment of God. I don’t want to speak for all people because they are entitled to believe in whatever they want.

Let me tell you a story. When I was in graduate school, a group of people came to me and proselytized. They told me Earth is 4,400 years old. I pulled out a rock and said, this is 4.3 billion years old and it came from this solar system. The magic of science allows me to know that through the radiological clock in that rock. They were at a loss for words.

I think the magic of human beings evolving is every bit as magical and beautiful as creationism.

Will robots become so smart one day that they overcome our need to send humans to deep space?

Realistic expectation of the funding resources NASA is privileged to have do not allow us to imagine a future in which fourth-generation robotic capabilities and quantum computing become realities, and we never need a person in the loop.

But even if that happened, we still want people there. Putting people in the loop will give us a more rapid return of our investment. We are also challenged by the Space Act to send humans into space, where it makes sense. Human spaceflight is part of our responsibility to the taxpayer.

What do you consider a fundamental physics mission, and is NASA doing enough in that area?

Fundamental physics is all of the governing equations that define the forces of actions that operate in the universe. Even biology is part of that fundamental physics. And so, we have missions that attempt to test how well we understand those laws. The results of the Gravity Probe B relativity mission are coming in. And we have the Beyond Einstein program, a set of missions that will go way beyond Gravity Probe B to look at the Einsteinian physics of the universe.

So, we have a broad, balanced program that’s being focused by the vision. Is it enough? We won’t know until we make the next step of discoveries to which we will adapt. If we see, oh my God, we went down the wrong path, our program is significantly resilient to respond.