NOVA; To the Moon; Interview with Leon "Lee" Silver, Ph.D., Professor of Geology at the California Institute of Technology, part 4 of 4

on Well, when they said this, they could see this orange soil incidentally, we could begin to see the orange in the video that was coming back because they had color video by that time. Boy, I was excited. And I thought that what this represented was a confirmation that this was, in fact, a volcanic vent which had had stream steam going through it which would have oxidized the iron contents in these things. I was dead rock. And what it turned out to be was that there was a layer of orange soil which was comprised

of small spheres of glass about a quarter to a tenth of a millimeter in diameter, okay, which was just lying across the surface, not right at the surface but just beneath the surface and it had been flapped out due to the impact in there. You did some very good things immediately. They trenched. They drove a sample tube which went down a meter and they made a wonderful set of collections and I thought for sure we had it. When it came back, it wasn't that way at all. It was directly analogous to the clods of green glass beads that we had seen at 15 except that they were orange. The orange color comes from the fact that at this particular mariage which was serenetitis, there's a great deal of titanium plus three, that's the coloring agent which made it orange instead of green.

The fact is they were chemically very similar. Now to appreciate that, you have to know two more things about it. These glasses had essentially no crystals of any kind in them. That means that the rock material has been heated to super heat above, if it had just more than just above the melting point, up to the point where it was totally liquid. We have to ask when did that super heat occurred? Same thing was true for the green glass. The second thing you have to know about it is those glasses were coated with volatile metals, volatile elements like nothing we'd ever seen on the lunar surface. Our model very quickly became that what we were looking at were the products of fountains, of melt which had come from deep in the moon where the temperatures were much hotter than they were where the lava's come flowing out on the surface so that everything was still molten. This stuff had fountained into a vacuum which is the best way to make perfect spheres and

each one of these things is a perfect sphere. We think then that we have samples which came from deep within the moon. How far we can't say, we don't know. We also found that they were coated with these volatile compounds which we had never seen in such abundance or with such isotopic signature before. Telling us that the interior of the moon might be very different than what's at the surface of the moon and that's where we left it and we're still hung up on that question. What is the interior of the moon like? Now tell me, you were the only scientists to ever communicate directly with the astronauts on the moon. It's a painting picture of that conversation that he had in the sky in Ireland at that time. How do you feel about it? How do you feel about it? Well, was it excitement? Well, there was a hell of a lot of excitement but that wasn't it. We're so full of all the good things that had happened to understand and I didn't initiate

that phone call. I don't know how it got initiated, I don't know if the crew did, I think it might have been George Abbey. I'm the guy I mentioned to you but I'm not sure how it was but I tried to give them a sense of the large number, very important things they had done and I've just kind of overwhelmed for myself. I wasn't thinking that I was the first guy, the first civilian or layman or scientist to talk to him. It was such an exciting time and we had accomplished our mission, they had accomplished their mission and we had helped in the back room and even if I was wrong. How about, let's just quickly go through 17, how did CERNIT do? Beautifully. Talk to me about Gene CERNIT. Well, I'll talk to you about Gene CERNIT, I have to go back to before 17. Gene CERNIT had been the commander on the backup crew for Apollo 14. With Joe Angle, they were going to be the landing crew.

They unfortunately had their commander as their working model when they came to the difficult question of were they going to put a scientist on the moon and they finally decided to put Jack on. They had to dump another hero, Dick Gordon, who had flown as the command module pilot on Apollo 9 or 10, I forgot which one it was. And they had to dump Joe Angle, who had put in his time and was rated very highly in there. So he had to put Gene and Jack together and I say we, I had to work with training. I have to say that at this time a major change occurred in the training and that is that an old buddy of mine, a classmate of mine here, Bill Mulberger took over and he was leading the training at that time. I was doing selected training experiments, but I wasn't doing all the training. Gene stepped in and the first exercise I did with him, I did in the San Gabriel Mountains.

And I was concerned because I knew that Gene had his model in the way in which the commander of 14 had operated, but I took him to a road cut right on what we call the Angelic Crest Highway and a broad enough place where you pull the cars over and I asked him to look at it. And I told him, which is a main major theme in all of my discussions with the astronauts, there is order in anything you look at. If you just let your eyes be open and not try to formulate order where it doesn't exist, just let the order come out and talk about it. And Gene started talking.

And from then on, although he didn't have the background that Jack did, his observations were just as acute, not maybe as well-formed, well-informed, but just as acute as that. And he worked his tail. And when we had the 25th anniversary in Washington of 17, I told Gene that and he liked that. Tell me the story of the science back room and the comparison of his ray. Oh, well, the Copernicus ray, and that really comes from the mapping of the Asterogeology branch, again, led by Gene. And one of the things that Jack had done while he was working for Copernicus was to map the quadrangle of the moon, and it's a segment of the moon, which contains the Copernicus, and work out of sequential geological history, in geology, sequence, means an enormous amount

to us. And so one of the questions that came up, when we're simply just scratching the surface literally, are you looking at something which originated at the place you're at, or with the dynamic processes which helped evolve the lunar surface, are you looking at stuff that might originated from a crater, a big impact crater, far and far further and further away? Well, at both Apollo 12 and Apollo 14, we thought we might be seeing the ray material mapped out by Jack and the other survey people, which covered both those sites. And then the question was, if it was that which of the samples that were collected might represent that ray. Now I don't know how far you want me to go because that was something I got deeply involved in myself, and it permitted me to suggest an age which was independently confirmed by

a totally different approach of about 850 million years, which makes one of the youngest features on the lunar surface, and that's why you can see it with the naked eye, you can see Copernicus up there. And that was vital to Jean, because Jean was trying to compare or trying to calibrate a changing history of the flux of impacting objects on the lunar surface. On the earth we can't do that very well because we got a dynamic earth which is always erasing the record, but on the moon we don't. So for him to have a time point, a possible time point, so Jean became very, very excited about that, and Jack was excited about that too. That's where I remembered that. Would you say Apollo 17 was kind of like the zenith of the geology on the moon? I don't like to use the word zenith.

I felt that we were building a body of data, a body of science. I'd rather talk about the depression that followed 17 than the zenith that 17 might have been. Well, the fact is that we're getting to be damned good at devising and implementing first-rate experiments, and we were learning more and more. And we got more sample, more good documentation, more ground covered on 17 than we did on 15. But 15 was the first one we'd ever used to rover. 14 had the Lazy Little Carrier, you know? So I don't want to call it the zenith. I just want to say it was a demonstration of improving science all the way through, reaching as far as we could go, and then it quit. Was I bitter about its quitting? I was unhappy, but I wasn't bitter. In science, we've got to learn that we can only...

Site selection. Was there a lot of debate about the site selection? Were you happy about the site selection for me? I was reasonably happy about it. Yeah, I had my preferences, but my preferences, like most of the people who participated in the site selection, were rather poorly informed. It wasn't until we got through to the kind of photography we were taking from the orbital phases of the later missions that we really began to see what was there. And the geologists, like everybody else, have hits and misses, on Apollo 16, we misread it. And I'll take my share of the responsibility in saying that we didn't give the cruise as good a geological context as I would have liked, and in part because it was a difficult place to do the context. The other thing is we had a landing site which required special demands on the rover. These guys had to climb hills, go past craters, and it was not black and white as it had

been in most other places. It was down here all white. It was hard to see it. But what the cruise brought back, what they did, was superb. Now what we were sure on were opportunities to get geophysical data. We didn't leave enough seismometers active on the moon. We weren't prepared to make them active experiments as opposed to passive experiments. Here we have in Southern California our seismograph networks are out there listening for what happens naturally. Well, companies can't afford to do that. They go out and they set off explosions. We didn't have enough signals to get into the interior of the moon and we didn't learn as much. In 2016 we had an unfortunate mistake, nobody to be blamed for it. John Young had just completed drilling a hole, was in placing, and drilling holes was very tough, and placing the sensors, and then he stepped back and accidentally caught this strand of connectors which would go to the, the offset, and tart loose.

And there was a desperate effort with Fred Hayes then in the suit on Earth trying to figure out how to do it. We could not get it back online. But we lost a real understanding of the energy of the moon. And I really felt for the guy Mark Langseth was the PI in that he's passed away on. But I wonder, did you think that NASA was too concerted in the landing sites? No. I think there was no place at this stage of lunar exploration where we could land and fail to learn something. Lots to learn. The question was always optimized, optimized, optimized, all the way through. In retrospect, what did Apollo teach us about the moon? Did we learn about the age of the moon? We learned to respect the limitations of our age dating methods. When we had an Apollo 11 landing there were people who were claiming that we knew the age of the moon, and it was exactly the same as the age of these Bessolidate Condrides

that I had mentioned earlier. We didn't. But with time we began to see a history of events and we began to put more and more timing into an understanding of the sequential development of the lunar surface. And we got back up to where we were at 4.3, maybe at 4.4. We don't know yet whether the moon is 4.3 or 4.55. 4.55 is essentially the age of some of the oldest meteorites we have, 4.56. We haven't got that mail that well. And the reason is that the lunar surface is a highly disturbed surface. And you can't get an old sample that hasn't been through hell. That's why the genesis rock in its own way, even though it didn't give us an age, gave us a primitive quality that was exceedingly important to us. And we've seen a few other such primitive qualities. We know now how to do the experiments better than we did then.

One of the great things that the moon experiment did was to out-quip a set of superb scientists with superb laboratories. And they have been turning their stuff on not only on the moon, but what we did on the moon, we've turned back on the Earth, and we're turning it on meteorites, we're preparing to turn it on Mars, we're learning how to do the investigation of the history of the solar system. Can you understand? Much better. There was continual growth. There were bitter arguments, great disagreements, all kinds of other stuff. But the fact is we learned, we learned, we learned all the way through. Absolutely. We must go back. There are things about the moon, which are relevant to the history of the Earth. This is what shoemaker, more than anybody else, recognized in there, would tell you. If we want to hear the early bombardment of the terrestrial planets, in the way in which they accreted, and where our atmospheres came from, and why we don't have atmospheres in other places, we have to use all the different solar system bodies we could layer hands on

and make measurements on. Each one is different. Each one has a different story. Why is there this incredible atmosphere on Venus when it's about the same size as the Earth? Why don't we have that same kind of atmosphere? We don't, you understand. Why is a mercury so free? Well, we can speculate on that, there are lots of speculations. What about Mars? When we first got the good pictures of Mars, people refused to believe after the dry moon experience that there might have been a lot of water, but you couldn't ignore the geomorphological evidence for fluids flowing across the Martian surface. If we want to understand our origins, one of the most important things we have, even if we finally figure out all the human genome components, we still have to know how they got to be the way they are. We have to go through the whole physical world of the solar system, and of course now, with wonderful astrophysical and astronomical capabilities, we're recognizing that there

are other planets around other stars, and we're getting there. But the moon is important. Oh, but the moon is a central, it is the best blotter of past signatures to understand that we have in the solar system right now, and it's the easiest one to get to. Now other people, Jack Schmidt, will give you a different argument. He wants to get helium-3. We're not ready to use the helium-3 yet, maybe in some day he's right, except that as a conservationist, I will be unhappy to see us mining large parts of the lunar surface. I want that moon that I saw come up the other night. Did you see the full moon? I wanted to see that one, but that may blotches on it. Okay. What could Apollo mean to you, Dr. Sondar? What level are you asking, personally?

Scientifically, it was incredibly exciting. I've been involved in other kinds of high-intensity science, nothing quite like that one, and I found that I was wearing out. I was so overloaded with new ideas, new data, and with the burdens of keeping things going. And actually, Apollo 17 was a good resting point as far as I was concerned. Okay. I'm talking to you personally. And for personal reasons, which I don't want to put out right now, there are a lot of other things going on. But what Apollo 17, more than anything, did for me, is to show me the importance of being able to mobilize talent, which is out there, and to focus it, and to achieve important things. It was a young sprout in World War II, I was just, I get out of the Navy when I was 21. I didn't really understand what teamwork and collaboration and getting the best out

of people was concerned. It really impressed me with the capability of the assembled talents and motivations of people, what you can do. And I'll tell you, there were 400 to 1000 people involved in Apollo. There were a hell of a lot more than that, who nobody's counting, you know, my postdoc who didn't have a thing to do with Apollo, normally, in this thing, but who worked like hell to wash the dishes. The number of Americans who lent their strength and their smarts to it was just incredible. Since then, probably in part because I was involved in Apollo, I've been an older man, I go to Washington, I serve on committees, nationally served console and other things. The importance of people putting their best intellects and skills in time together with the best motives, not for a personal gain, but for the best of all. It is something I think is an essential part of the American spirit.

We're volunteer citizens, you know, we're citizen people. I really am impressed with the flight controllers, the engineers, the people who ran the hotel and all the other goddamn things. We can do things that are just incredible. It was really a super thing. That's aside from the science, but God, it was overwhelming to see how people pull together. Okay? Okay. Okay. Okay. Turn. Turn. Thanks.