And then you know a lot of very smart people said it would be advantageous to put the rover on the bottom (of the spacecraft) because then we can land it on the wheels. And the moment they said that, I said yeah, of course we can do that. So I was part of the beginning of the gestation of the whole thing.

Light Years: Do you think you'll ever use the sky crane again?

San Martin: Yeah, oh yes, I mean the sky crane now is a proven architecture. I think that all of the fears, a lot of people said that's very complicated, the fact that we didn't test it on Earth ... our argument was that it looks complicated, but actually the physics of the problem are pretty simple. And (in the) simulation we felt very confident. Now, the only thing missing from that argument was to actually try it.

And now we've tried it and we can say it looked easy and it was easy. And when I say easy, I mean not that it's cake, but simply that with a simulation you can prove (the system). You don't actually have to fire the rockets and do the whole thing. There are certain engineering designs and engineering architecture like the airbags ... you really need to test it in very similar environments, because we don't have the technology by simulation to feel comfortable that it's going to work.

So yes, we'll be using the sky crane again for these type of missions. There might be some other ones where things are small, where we might go back to the airbags just because of the cost issue. The sky crane requires good thrusters and good radars and that brings the cost up.

Light Years: Tell us about how you came to NASA.

San Martin: I was born in Patagonia, in the south (of Argentina).

I grew up during the Apollo era, and I grew up with ... an inclination to everything that was engineering. My father was a civil engineer, that maybe was part of it ... a lot of people at JPL were the same way. I wanted to do engineering.

Then I became conscious of the Apollo program, and when I was 10 years old saw men walk on the moon, and that caught my attention. But really what I feel was the mission where I decided "this is what I want to do" was the Viking mission, in the '70s. It was the first lander, and I found out by just, by, you know, by coincidence. It was difficult to find out about these things. It was several years before it launched and I immediately became interested.

I got like ... people did, on August 5, and watched (Curiosity) landing. I tried to do that (with Viking), except I found myself in Argentina, in the Patagonia, in my family's farm, listening on shortwave radio to the BBC where they were telling the story. And it went off the air because the program ended! Then I had to find out the next day. I went to the town and bought the newspaper and saw the picture, that Viking landed. And I said, this is it, this is what I want to do in my life.

So, well, it started at a very early age, and I found out about JPL through Viking, so I had a destination. I knew it was in Pasadena, California, but I don't think I could point to where California was on a map, just that it was somewhere up there in the United States. That's when I decided that the best way to do that, and my father encouraged me, was to go to university in the U.S., and through that ... be able to figure out how to do the stuff I wanted to do.

Light Years: Have you modeled how to take humans to Mars?

San Martin: No, I haven't worked on the human side. I had some colleagues who had been doing some work on that, so I'm not an expert on the subject. The only thing I know from talking to them and reading their papers is that when we bring humans to Mars, it's going to be very different from how we do it (with rovers) right now. We don't know how to land the amount of weight. The amount of equipment that you need to bring with astronauts, with humans, would be like 40 Curiosities. It would be like 40 tons. And you cannot launch 40 rockets, because obviously a human needs all of that at once. So we don't have the technology to do it ... but NASA is starting the process of learning how to do that.

Light Years: Will it happen in your lifetime?

San Martin: Well, I would like to believe so. But you know, I doubt it, to be totally honest. I mean, I think it's a matter of priorities: national priorities and world priorities, because I think that it will have to probably be an international endeavor, no single country can do it. But we are going in that direction, so maybe one day it will become a priority. And the moment it becomes a priority and we get the right funding, then it can be done.

Light Years: Do you think private spaceflight might influence whether we send humanity to Mars?

San Martin: I don't know. I think that ... what they are doing right now, which is to build spacecraft that will be able to take humans and cargo to the space station, that that's one set of problems that I think they can succeed, doing that.

To be honest, in the past, the spacecraft that NASA sent to the moon was built by private enterprise, too, you know ... so I would imagine if it's private space, it'd have to be a business model ... I'm not an expert on that, so I wouldn't be able to comment.

Definitely private space for low-Earth orbit, what they are doing right now, I mean it seems like a valuable thing to me. They're showing a lot of success so far, SpaceX.

Light Years: Has NASA started planning for another Mars rover, in a few years?