NOVA; To the Moon; Interview with Graham Ryder, Geologist and Lunar Scientist, part 1 of 2

Askew is about how you get into the field, I'll say. And that field would be what? How did you first become involved in studying in lunar science? OK. So you want me to answer that now? Sure. I did my PhD in geology, working on terrestrial and ortho-sites, which is a very plagiarized rich rock. And having completed that, I went to work with John Wood, who had discovered an orthositic rocks on the moon. And so it made a very good match for me to try to figure out a lot more about what was happening with the ortho-sites on the moon. And that was where I got my start into lunar samples that is an understanding of the moon. And I've never looked back. Can you tell me what an orthosite is for the moment? An orthosite is an igneous rock, meaning that it was made from a silicate melt that was very hot, and it crystallized. Unlike most igneous rocks, this crystallized, we have to start that again. Go ahead.

Now let me think about that. How you explain that for the layman is kind of difficult. An orthosite is an igneous rock, meaning that it crystallized from a silicate melt that was a position of minimum retreat that people take on their ideas. And if a new piece of data comes in, they try to fit it into what they already know. Sometimes that doesn't work. I came in completely fresh on that. And I didn't have a biased point of view. I didn't know what to think. So I had completely open feel. But I already had a lot of information to work with that other people who produced over that four or five years since Apollo 11 had first landed. Great. I'm going to stop you there. We're going. OK. So start again on that and tell me, what advantages did you have? You don't want to pursue the an orthosite part of that? No. Let's clear. Are we clear on that door now? Yes, I'll take you to clear it. All right. Coming in in 74, the two years since the last mission, the rocks have been there. Tell me that again. What was your advantage? My advantage was that I didn't have any preconceived notions about the way the moon was or should be.

I hadn't built it many by having to do fast work during the Apollo missions. And so I came in with a sort of fresh face, basically, on ideas with a clean field. And a lot of information that people have produced and the ability to now produce some of my own data to find out what was going on. And so it was very good for me to be able to have that open field to work with without any prejudices. Graham, what do you mean by fast work? Tell me what happened when the first rocks came back. Well, people did have to work very quickly. Apollo 12 was going to take off only a few months after Apollo 11 landed. And people wanted to get their work done. They wanted to be the first with their ideas. And so a lot of work was done very fast. Most people would take their work at a much slower pace than people did with Apollo 11 and Apollo 12. So it was a very rushed kind of time. You don't really have time. They didn't really have time to reflect on what they'd done adequately. Scientists actually wanted the Apollo missions to be spread out over a much longer period of time to give them that time to work with. But they didn't get it because the engineers

and politics, and politics, of course, said go and do all these missions and get them over with. Well, let's talk about that. What sort of time frame set for purely science, typically, what would have been ideal in between missions? Well, that's hard to tell in advance when you don't know what's coming back. But it was fairly obvious that the samples were fairly complicated. Many of the samples, for instance, are breaches, which are mixed rocks, consisting of lots of little bits. The soils themselves, which were always collected on the missions, are made up of lots of little fragments. And so it takes a long time to work out what everything is and what it really means in terms of understanding the moon to come up with an idea, check it out, go back and get some more information on the samples that you didn't already have, that you predicted should be there or whatever. People, I'm pretty sure, would have liked to have had a year between each mission to be really optimized what they got before the next mission, crowded and out with having to go and get new data very fast. Not being familiar really with the field. I thought, OK, the rocks came back. I assume they got studied.

And now they're probably sitting somewhere. Is that true or is out of misconception? It's a misconception. Yes, a lot of the rocks are sitting somewhere. They're stored very, very safely. They're a national treasure. But people like me are still working on these samples. We're still finding out new things. Not just that some of the rocks have not been adequately studied, but new techniques come along all the time that you can apply to these samples and get new kinds of information out of them. Several techniques developed after Apollo that weren't able to be used during the Apollo days. They're sort of like studying Shakespeare and people still do it. You still find new things out. And of course, you've studied the Earth for 200 years as a geological body and people are still doing it. We don't know everything. You never quite mine all the information out of a rock. Not very fast, anyway. So these rocks are very much alive to study of them. Yes, we still have a sample team that looks into the allocation of these samples to investigators who proposed to work on them. And yes, there still be studied fairly intensively. Obviously, not at the level that there

was during the Apollo days themselves when everybody was trying to get samples to work on. It was a bright, gleaming business back in those days. Now it's not quite so hyped up, of course. But the study of the moon remains just as important. We don't know everything. We could know about it. Are you learning more from there? Oh, yeah. We'll learn more as we go through these samples. How about you, specifically, Jesus? I mean, you're actively working with the samples. I'm actively working with the samples from many points of view. One of my main interests is the chronology of the bombardment of the moon. So I'm looking at the basins on the moon, in particular, the samples that we have from basins to try to understand how those basins formed, how the rocks in the crust were formed from them. But basically, the chronology of when those impacts took place, which is very important for understanding the inner solar system that are in the early parts of the solar system. Fabulous. Let's cut from that. I need to catch my breath. I'll talk about the subsequent impacts.

That's what you're really talking about. Right. I look at the moon. I see it's covered with craters. Now, what do you know about that? It certainly is covered with craters. It was obviously even before Apollo landed it was well known and that they were impact craters, not volcanic craters. What I've been trying to work out is the chronology of that, the timing of those events. And what we need, actually, is more samples. But based on what we've got, it looks very much as if many of those craters were formed in a fairly short period of time at about 3.9 to 3.8 billion years ago. What we don't know is quite what happened before that time. And it's very hard to see through. But from the work that we've been doing, we think that the impact rate was not as high before that time as it was at around 3.9. So it looks as if there was a very intense spike in the impacting rate on the moon at around that time, which made most of the landforms that we see today and certainly most of the very large basins

that you see on the face of the moon. And I think we have very good evidence now for the ages of most of those craters on the front side of the moon and the large basins on the front side of the moon and that they occurred within perhaps 50 million years of each other, which is a very tight timeframe for that sort of thing. You mentioned a spike, so then it tapered off afterward. During the accretion of the moon, the bombardment was very, very heavy. Obviously, the moon was made in just a few tens of millions of years at most. And we have a very good record after that 3.5 billion years because the record is very well preserved. We can understand that. It's what happened in between about 3.5 and 4.5 billion years that is unclear. There was certainly a very heavy bombardment about 3.9, much heavier than there was at 3.5. But before 3.9, there doesn't seem to be evidence of the same sort of bombardment. We know what we're looking for. We're looking for melts that were made by impacts during that time, which

are the best to get an actual radiogenic age on craters. We don't see any of that sort of stuff. So it seems as if there was quite a light bombardment for maybe a couple of hundred million years before 3.9, maybe 300 million years. And then earlier than that, of course, then it was. The moon was being made. And that was a very intense bombardment at that time. But other people would suggest, perhaps, that it was a continuous bombardment and all that the 3.9 to 3.8 ages say are the tail end of all that. I think we have good reason from geology and from looking at the samples that that is not the case. But of course, it's really an open question until we go back to the moon and get a much better sampling of the moon than we already have. Apollo really didn't get all that much. They went to six sites. And that's all. And of course, did not do the sort of field job that you would want to do if you were doing on the Earth, where you would spend days and days and then go back to a site. You can't, that wasn't done on Apollo, obviously. So it was a very limited sampling that we have.

And sometimes we need to go back, sample other craters, sample other kinds of rocks, different parts of the moon to really understand what was going on. You said something very interesting a moment ago. You contrasted your work with Dr. Harbin. And you said, I'm a geologist. I study the rocks institute, can you tell me that again? Yes, I study the rocks themselves. And I try to get as much of the field context from the geology around the landing sites and the moon as a whole, as I can. Bill works in a somewhat different direction. Certainly he understands geology. He doesn't ignore it. But he is not so heavily dependent on what the samples themselves actually say. He is certainly more interested in the land forms and the cratering abundances, crater sizes, their numbers, per unit area, and that sort of thing, to model what might have happened. He's also more cognizant than I am about the possibilities for asteroids zooming around the inner solar system,

or planetesimal zooming around the inner solar system. And from the point of view of that, it's very hard to figure out why you would have an intense bombardment of 3.9 to 3.8. And of course, that's a problem for me because I would like to explain that. But I think my first job is to understand what the lunar record actually is. And the lunar record seems to say to me anyway that there was a very intense bombardment for a very short period of that time. It's cause, I don't know. Well, that's why Bill and I disagree. It's a waiting of the evidence, which is different, and just a different approach to how we're trying to understand the moon. We can't all do everything. We can't all know everything. Use the phrase institute, does that mean going back to the surface and does it mean going back with men? In situ means going back to the surface, yes. We need to get rocks from specific places that we think we understand geologically. My own opinion is humans are the best people to do geology in place, yes.

A limited amount can be done with robots. It's not just a sample collective expedition you need. You need to actually understand the context of the rocks. And to do it with robots is currently beyond robot technology and may always be most robotic techniques are very engineering oriented and not cognitive oriented. I've done some of this geology through a robot testing. And it's very frustrating, it's very difficult. You don't get all the answers you want to get. Whereas if you had a human there, you could understand what you want in a few minutes or you can't understand it at all because it's too complicated. So you'd like scientists astronauts to be on the moon now? Yes, very much so. I think the place that astronauts should be is on planets, on the ground, looking at things rather than orbiting them. That's the best way to use an astronaut. And if you want to understand the geology of the moon or Mars, you need to have humans there doing it, I think. Would you like to be one?

No. Just put me there, yes. But I don't want to sit. I don't want to sit none. Remarked, I guess Don Wilhelms in his book about the moon remarked either that either that I was smarter, very lucky. I'm probably lucky. That's great. Jeff was going to say on that is that each one gave us a site which had an age and a number of impact careers and helped calibrate this whole curve. But the US, the thing about what's the meaning of it all today. And we might want to go into that. Yeah. Great. OK. We're ready to roll. Maybe you could just tell me very quickly that point that we did land in a variety of locations and that each one gave us an age. And I assume that that was helpful. Yeah. The one moment, roll sound? See. Can I have a speed?

OK. A number of landing sites. What did we get from that? The later landings on the moon and the Apollo program were longer stay times and gave more data. But from my perspective, these were the first just handful of people, 3, 4, or 5 people that began to create that field. Fair enough. Jeff? Great. Happy for you. We could use, I didn't know, a pointer was your professor. We don't have it much on point for a warrior. Volcanism. OK. This is Rometown for the Hartman interview. OK. What? 30 seconds? One second. Rometown. Thank you.

Thank you. Can you tell me what the north side is for the land? A north side is an igneous rock, meaning that it was made from a silicate melt that was very hot, and it crystallized. Unlike most igneous rocks, this crystallized, we have to start that again. Go ahead. Let me think about that and how you explain that for the laymen. It's kind of difficult. A north side is an igneous rock, meaning that it crystallized from a silicate melt that was at very high temperature, as it called it crystallized to produce the mineral plagioclase, which is a calcium aluminum mineral. We're just going to take a quick pause in room. I'm sorry. Yeah. OK. Well, that gives me time to think about the north side. The significance of it is, since World 206 is going up, we're all wrong, you know, so gave me a material to work with. I didn't have a bias.

That's exactly the same as that. Yeah. I would like you to tell me that again one more way, because people's interest. It wasn't as if there were a lot of people thinking about the moon before Apollo. But they got the frequency that they, as some of them, had them before the missions. And some of them had them because they started to work on the samples during the missions, but they quickly got ideas, and they didn't necessarily change them very fast. There's a position of minimum retreat that people take on their ideas. And if a new piece of data comes in, they try to fit it into what they already know. I see. Sometimes that doesn't work. I came in completely fresh on that. And I didn't have a biased point of view. I didn't know what to think. So I had a completely open feel. But I already had a lot of information to work with that other people who had produced over that four or five years since Apollo 11 had first landed. Great. I'm going to stop you there. We're going. OK.