GLENN: Leroy Chiao, he's an astronaut with NASA. He was the commander of the international space -- was he the -- Leroy, you're here. I should probably ask you.

LEROY: International Space Station.

GLENN: International Space Station. And aren't you the guy who went -- you have piloted Russian and Chinese, or just Russian vehicles?

LEROY: Oh, no. I'm an American. I was born in the US, and I flew three space shuttle missions before traveling to the international space station as a copilot aboard a Russian space craft and I was the commentary of the station for six and a half months.

STU: So you haven't really accomplished much in your life.

(Laughter.)

GLENN: Leroy, just on a personal aside, what is it like to come back to earth and look up and go, I'm never going back there, and it was the coolest thing ever?

LEROY: Well, you know it's kind of funny. I mean, when I got selected to be an astronaut, I never imagined the day would come when I would decide to leave NASA. But, you know, during my first two weeks at NASA, there was a going away party for one of the senior guys, and I overheard somebody talking to him, and talking to another guy, and how do you know when it's time to leave?

And he said, when it's time, you'll know.

And I remembered that. And 15 years later, sure enough, I was getting are they to go fly to the International Space Station -- or actually I had just gotten back, and the chief asked me if I would stay for another shuttle mission, and I thought about it for about 30 seconds, and I turned him down. And I surprised himself, but I had done everything that I could do and hope for in a flying career, you know. I've flown space shuttle missions, I've done space walks to help build the space station --

GLENN: What is it like --

LEROY: -- and done all that stuff, and it was time to do something else.

GLENN: Is there anything that the average person can compare to walking out into space the first time?

LEROY: No. It's -- it is, you know, even the sixth time, it's a bit of a surreal experience. You're actually in the space suit which you can think of it as a personal space craft. It's got all the life support system and everything. But you're all alone. There's nobody else that can help you except for your partner who's out there with you.

But, you know, it's kind of a weird feeling the very first time, looking back through the shuttle windows and waving to my buddies inside who are about three feet away, but something happened, we were out there alone, and, you know, it was kind of up to us to save ourselves.

But, you know, it's okay. Because we're well trained and everything works well, and, you know, certainly there's risk, but you know what to do.

And, you know, we were able to get our jobs done, but it is kind of a weird thing, you know. [Laughs.]

GLENN: Yeah, I bet it is. I wanted to ask you about the Chinese shot of the -- what is it, the Chang E?

LEROY: Yep.

GLENN: Can you explain, going on the other side of the moon, it'll be the first time really that we can hear deep sky, or -- or radio without all of the static from earth. Right?

LEROY: Well, hmm, not really. Because you still have to relay through that -- that relay satellite. Right? So, you know, you're -- the fact that they're going to the far side of the moon is unique. Nobody has landed a probe over there. Not for any particular reason, except that, you know, you have to have a relay satellite in order to communicate with it. So they've got to first put that relay satellite in that HALO orbit so you can relay messages from the far side of the moon back to the ground stations on the earth. But it's going to be interesting to see if there's any difference between what we found on our scientific probes on the side that we can see versus the far side.

GLENN: Why all of a sudden -- and I think it's a great thing. I'm excited with, you know, with what Elon Musk is doing and everything else. But why all of a sudden do we have this race, it seems, to go up into space again?

LEROY: Well, you know, you're right. The commercial side has been the very exciting wild card. NASA has been going along. We've gone the shuttle program, spatial program and we're plodding along with exploration, although there's been no serious -- or know significant, I should say, or farther advancing political and financial commitment to that. There's been a lot of talk, but -- and we are hopeful of developing the new vehicles, but it's Elon Musk and Jeff Bezos, Space X and Blue Origin, and here were two guys who are visionaries and who are willing to commit their resources, their personal and influential resources, to go ahead and do exploration. That's never been done before by commercial companies.

You know, where's the profit in colonizing Mars, as Elon Musk wants to do, or in the case of Jeff Bezos, he wants to build infrastructure in low earth orbit and out into cis-lunar space. So he's kind of going -- sounds like a Field of Dreams thing, build it and they'll come. But it would be difficult to get like a Boeing or a Lockheed. There's no way their shareholders or boards would let them go do these things. But these guys, they're out there and they're serious. They're building rockets, launching rockets, and it's exciting. They're pushing exploration for the first time we've got commercial companies pushing exploration.

GLENN: How realistic -- I've read that helium 3, the moon is rich with helium 3, and if you had a fusion system, that you could -- if you could fill the space shuttle with helium 3 and it would run -- it would be enough power for the United States for a year. Is there any way to transfer this or use this?

LEROY: [Laughs.] Well, helium 3, I mean, helium 3 is present on the moon. But it's in the soil in the parts per billion concentration. So that is, you know, for every gram of helium 3 that you might harvest, it'd be a billion grams of regular, you know, lunar soil that you'd have to go through and find a way to separate this stuff out. So it's theoretically possible. You could even -- theoretically possible to separate the helium 3 and store it and bring it back to earth. But the other part of the problem is we don't have a fusion reactor. We've been 20 years from a fusion reactor since the 1950s. Right? And so -- [Laughs.] -- we need to invent a fusion reactor that is practical and actually works before -- before we talk about bringing helium 3 back from the moon.

But people, you know, have used helium 3 as a justification for going back to the moon. And to me, that's nice, but there are a lot more practical reasons to go. If we're going to go to Mars, the moon is the perfect place to prove your equipment, to train your crews, to get some experience before sending all that stuff to Mars, because the moon is pretty close. It's only three days away. If there's an issue you can get your crew back. Mars on the other hand, closest approach is on the average about six months away.

STU: As we saw with Matt Damon.

GLENN: That guy, man.

STU: He's had a tough time. Many journeys are turned out poorly for Matt Damon

GLENN: Leroy, when you hear the size of the rocket that Elon Musk is building, he says it's going to be 40 stories tall and with fit a 747 inside of the day when you see -- and I know this is Hollywood, but when you see these movies, and we are developing eventually some sort of inner planetary, you know, vehicles, they're enormous. Do we -- do we build those in space on the moon? Or do we launch them?

LEROY: You know, there's different ways to look at this. Elon Musk did announce these huge rockets that he wants to build. And that's to support his vision of colonizing Mars.

So he's envisioning building space craft that can take 100 or more passengers to go, you know, start to colonize mars. There's two schools of thought. Either you launch it all at once and you have to have a huge rocket to do that or you build gas station in, say, low earth orbit or orbit around the moon, and then you launch kind of an empty vehicle out there and then fuel it up to go. Right?

So there are pluses and minuses to each approach, but what Elon is talking about is building a huge rocket, much bigger than the Saturn 5. In the 1950s, 1960s, the United States, it was called the Nova rocket. They had these ideas where they were going to build these similarly huge rockets to do interplanetary explorations.

So there's certainly something to that. There's some history to it. You know, the thing with Elon Musk that I've learned, he may not make the exact date that he projects, but by and large, he's able to get things done. You look at the successes of Space X, with Falcon 9 and with Tesla. It's pretty impressive.

GLENN: So if Elon Musk called you and said, hey, I want you to come and colonize Mars, you could take your family, would you do it?

LEROY: You know what? I would love to go explore Mars, but I have no interest in living there. Life is much better here on the earth. Earth orbit, it's great to go out there and have the adventure, but I'm going to come back here.

GLENN: Leroy, thank you so much. I appreciate it.

LEROY: My pleasure.

GLENN: Leroy Chiao, an astronaut extraordinaire, and something that the early astronauts did not have the opportunity to do, and that's to go back into space over and over and over again.