After 10 years managing NASA's International Space Station from Houston, Mike Suffredini has announced plans to step down this fall and take a job in private industry. In a wide-ranging interview with Chronicle science writer Eric Berger, he spoke about what the station has done for space exploration.

Q: What's been the best part of your job?

A: Just being this close to such an exciting thing. I've watched this vehicle get built, struggled with how to operate it in the most efficient way, and it's hugely gratifying to watch people solve these problems. This is the largest peacetime international project in human history by some counts. To be a part of that, and playing a role in extending this species, perhaps for a much longer period of time, you couldn't ask to be involved in something more important than that for humanity.

Q: With the space shuttle there was a lot of responsibility for a couple of weeks, and then the vehicle came back and everyone could take a breath. With the station, you're flying all the time. For 10 years you could get a call at 3 a.m. in the morning and there's some disaster in space. Was it wearing to be in the hot seat for 10 years?

A: I'd say it takes a certain personality to do that, because you are aware of it. I'd say there are certain risks with ISS that we can only manage, we can't do away with them. The environment of space is harsh. There's an object out there that's small enough that we can't track it, but big enough that it would be a really bad day if it hit the station. Sometimes when you can't sleep at night you remember that that's out there, and it just helps you not sleep at night. But you have to have a personality that can compartmentalize that risk, and work on that risk. It's always there. You're always a phone call away. But to me that's always been what was my energy about my job, it was always happening, and part of my job was to be there when the phone call came. It does wear on you at times. But you can't do great things without great challenges.

Q: Do you feel that with your work, and that which the ISS program has done, that you've taken what was theoretical - the exploration of space through an international partnership - and proved it can work?

A: I think we've proven two things. I think we've proven that it works. And I think we've proven that it is clear that such a model is mandatory for exploration. The U.S. government has the wherewithal to explore, but politically with everything else we have to do, that will never happen on our own. So I think what we learn from this is that it's much more possible with a partnership. It's difficult to manage, but the stability you get when countries all start to play together is important, and even when something goes wrong, they have this big commitment. When space shuttle Columbia was lost, the question was asked: Do we keep the station around? If we hadn't had the partners deeply involved, we might have walked away from the station. So there's stability and funding that you get from a large international partnership. And it just makes sense. We're exploring for humanity, not just the United States or Russia.

Q: The station is formally extended to 2024. Structurally it's probably OK until 2028. What's your best guess about how long we're going to fly the station?

A: That's a good question. It's so fraught with politics. I would say it this way: When as a partnership we all decide we don't have to have a station to do the next thing we want to do, I think we'll begrudgingly let it go. I'm hoping by then we will have done enough on the station to make it commercially viable to go build a station to replace it, and there will be something in low-Earth orbit. It can stay in orbit longer if need be. I'm betting we'll go to at least 2028.

Q: What's one thing you've learned, if you went back and told yourself 10 years ago, would surprise you back then?

A: There's probably a ton of them. Ten years ago, commercial use of ISS was never considered. Governments needed this platform to do what governments do. And now we're learning that while the government has uses for the platform, really, everybody can benefit from this. That's a big deal. I've learned that you've got to learn how to control a vehicle without operating everything. Individual countries and companies manage their launch programs and you have to be able to be flexible enough that they will fly when they are ready, and you have to accommodate them. We never imagined that. We thought we would set these launch dates, and they would launch by those dates. And 10 years ago, I didn't really appreciate the significance of what we were doing in terms of the multinational aspect of it, and the implications to humanity in general, both near-term and long-term civilization. That is something to me that I've noticed as the dust finally settled and we finished the assembly of the station.