During one of those times that I was at Stanford, I was… I taught in the Department of Medicine, I was a visiting… professor, in… in the human biology program. A friend of mine, Bill Hurlbut, invited me to go to a… a workshop that was taking place at NASA Ames Research Center. Now, NASA Ames Research Center is about I think seven miles south of… of Stanford, and it's a huge NASA base. It was an army base initially, then it was a navy airfield, they have a huge landing strip there, and then it became a federal airfield and then NASA took it over. They used to keep a lot of their aircraft, experimental aircraft, there but they… they had moved down to Dryden by the time I arrived. But, in any case, so I went to this workshop and it was a workshop to establish a program for astrobiology. Now, the term, the word astrobiology probably goes back to the 1930s. We did a little research on that to find out its initial use and the current definition, simple definition, that… that we use, and I think it's probably an adequate definition: it's the study of the origin, distribution… origin, distribution… I guess and future, of life on Earth and in the universe. Okay, so, essentially, it said, the question is, is there life some place else? Well, in order to… to know about that, you have to understand how life started here because there's plenty of evidence that, you know, based on some of the, I guess, some of the Jupiter missions, in that… that Mars — the best possibility for a place for life in our solar system — was a pretty arid place, there was no evidence of liquid water, and… and the astronomers had worked out the early history of… of our planetary system and there was reason to believe that in the early million, billion or so years, or hundreds of millions of years, that… that Earth and Mars had… had quite similar environments and they diverged greatly since then. So the notion was if we were going to recognize life on Mars, we should really know about life, origins of life, on Earth, what life was like in early days. Now, early days means— really early days is about 4.7, I think, billion years, that's the origin of the… of our solar system. Now, it was like a turmoil on… on Earth in… in the first billion years, less than that, a few hundred million; lots of volcanic eruptions and if there ever had been life to start with, the Earth was in effect totally sterilized, really upset, you can't get geology going, you know, for the first couple of million years because it's all been changed by these… by, you know, by lava flowing all over and, you know, good parts of South Africa and Siberia are just huge lava fields. So, and also there was a lot of impact activity in the so-called Late Heavy Bombardment, the… a lot of the asteroids that were in the asteroid belt between Jupiter and Mars, their situation was somewhat unstable, so a lot of them, you know, left orbit and eventually ended up on Earth and on the moon. Well, things that happen on Earth, impact on Earth, you can't see because we have weather, but the moon is… is a reflection of what happened to Earth. So you can… you can figure out the intensity of… of impact by looking at the moon and you can often tell late ones and early ones too, the way they're superimposed on each other, so you can kind of date the periods of great activity. Now, there is even more on Earth because… bigger cross section, and, but now there's about, I guess the last figure I heard is something under 200 known impact sites on Earth, a lot of them discovered from the space station or from the shuttle, because the astronauts are trained to look for interesting stuff and they're given a camera, they have multiple cameras, and when they have kind of free times they sit and look out there, you know, in the porch windows, so to speak, and photographing things they find interesting, but also they have a kind of program that's… we're going to look at the delta of the Nile, you know, for the next… for this mission or something. But they… but a lot of the impacts were found in that fashion. Nobody had recognized them, that we had impact craters, until the 1960s. I diverge a little bit. So I went to this... I was absolutely fascinated by it, and I, you know, and they had invited several hundred scientists from all, you know, from many fields, not just people who had been working with NASA and astrobiology, you know, geologists, medical people, even biologists, paleontologists, and I… we ended up with a kind of workshop, you know, a… a guidelines, in effect, boundaries, you might say, or programs, that weren't binding but they represented the content, the potential content, of the field. It was an elaborate document, there were multiple pages. Well, I got involved in that, you know, I asked a lot of questions and, you know, I got… I met my first NASA contacts which are still my best friends there, and… and I really was intrigued.