NOVA; To the Moon; Interview with James W. Head III, Professor of Geological Sciences at Brown University, and Farouk El-Baz, Director of the Center for Remote Sensing at Boston University, part 3 of 3

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You know that's the icon I thought I thought I was going to be by all boys of himself Oh, man, that's when I learned about the reverence for the First anything trouble is he's telling me about this thing and I yeah, so all of a sudden you know the phone Yeah, it's around You're hiding the goddamn AT&T So before 11 you guys are pouring over the sites. Yeah, why did you pick 11 and what were your fears about the first landed? What do we know about landing on the moon? Yeah, you remember there were five of them there was five because within that equatorial zone and there was There was the concern was really more of the absolute flatness of the surface and the lack of

Rocky terrain in the landing site and that was as far as I'm concerned These were the real critical aspects and when you when you don't have topographic maps and you have no idea what the flatness of the terrain is like Then you really better be selecting it right You talk to me to talk to me And I think I think one of the other things was that at this point we also didn't know how long it would take the astronauts to get organized Once they came around and started the descent of the moon so clearly having a very smooth flat place was one of the major concerns Safety was at the utmost concern at this point And so we had five sites that were all flat with some craters Etc and in the Maria, which would be interesting and it went sort of back and forth here Some people would say well the astronauts need a little bit more time to get ready to come down And so on as they come around the moon and get their signal again from the earth And then we want to pick one in here that gives us some forgiveness here and there And so it came one of the ones in the middle basically And this business of the flatness of the surface became supreme because if a surface is tilted towards the sun like that

It would look white or bright in the picture And if it is tilted the other way around it would black And therefore if it has in any other position it will be in shades of gray And that's the only way for us to have figured the flatness on the surface That we weren't there, we had no topographic maps and there was no other way for us To really figure out whether this surface is going to be flat or not Actually we invented a whole new process called photometry Measuring the brightness of the surface and assigning a degree of tilt to that Because if the surface was tilted more than 13 degrees The space craft would top it over and that would be the end of the mission and the end of that's or not And it had to be less than 12 degrees of tilt And there is no way for us to figure this out except with this business of how bright is bright Or how dark is the dark surface And one of the big problems was too If you landed on even on a flat surface on the edge of a crater

Some of these craters had slopes of 10 to 15 degrees in the inside And of course as a lunar module pitched over and landed they would just keep going over And that was not something you wanted to have happened because obviously you couldn't get off the moon if that were the case So there were lots of different problems Each of these craters also had boulder fields around it and that's what Neil Armstrong saw when he started to descend He looked at the window and said, whoa, lots of boulders here we have to move over to some other place So there were lots of concerns even on the flatest of the surfaces But nonetheless it was after the Apollo 11 site was And the things that you were told to look out for Now this is before the first land Remind me of that This is before the first land Okay, here we go, this is 196 T2 Two Now remember, this is before the first land Prior to the first landing on the moon, the main concerns were Okay, having a flat surface so that in fact you didn't You knew exactly where you were and wouldn't tilt over Not landing in a big crater because that would also destroy the spacecraft Looking out for these large boulders because you could land on one of those

Shelter spacecraft over et cetera, and of course dust And that was two concerns, the first one was that the spacecraft, according to some theories, Might just sink into the dust way over its head And therefore you'd never get off the ground again And the second one, even if you could land on a relatively solid surface The decent engines would kick up dust so that you might lose your bearing in the last few seconds And then tumble over So all of these things were a great concern and continue to be in many cases throughout the program Good Cut Now I'm going to ask people We actually had five sites for Apollo 11 to land from the east all the way to the west And that was basically if the launch schedule did not allow us to launch at the proper time Then we can give it a cycle so they can wait for a whole period for a day to land in a different place And so on, so there were a possibility for five landings anywhere and all of these areas

Satisfied the landing requirements being split away from creators, away from boulder fields or big blocks And most hopefully having no dust where the spacecraft would disappear All right, here's 15, pick it up while we're shooting Tell me about 15 as you're getting it together What was so interesting about 15 is how risky But look at Apollo 15 and see that's a whole different ballgame When you're getting into a very reasonably rough terrain Having the spacecraft come over a mountain and leading down to land in an area And not knowing whether they will land in a ditch or not And long ditch here ahead of them When they come in to land they are actually facing up They're looking up into space And they can't see the surface so they come over those mountains Literally looking up into space and then they pitch over and their first view is not very forgiving Because in fact they want to see the reel on the far side and the mountain behind them and a mountain to the side If they don't, they're in big, big trouble

Fortunately, they saw pretty much that view and were able to descend So that they didn't go to the far side of the reel Didn't land in the reel and missed the mountains It's really crucial Show me where they landed The Apollo 15 landing point was right here and they landed within a few tens of meters of that site Absolutely incredible When you hear the decent voices you can tell that even though they know they're pretty much on target And they had several craters here that they could, that they had for essentially landmarks So they could tell where they were Nonetheless, looking out the window on their left There's this giant mountain sitting there And you can just tell that it's like they're seeing this at the side of their window and it's like Should that really be there and you could hear the little tension and the voices And then they moved a little bit away from that So they landed a little bit off based on I think that lurking mountain in the window You would have done the same if you were in that space track to look down and see what that is You either want to land anywhere near that mountain I don't think I would have been describing the geology at that point

But nonetheless they really looked at it and while they were describing we knew that they were landing in the right place We knew that they are on the east side of this great big long ditch And we actually knew that they will make all of the objectives of the mission Looking at the going to the mountain, getting samples from the mountains, reaching the edge of the hill And taking photographs of the hill and they strata within the hill itself because that told us that basalt rocks are actually in layers It's important because volcanism became in spouts or separated by time So all of these things were important and the landing point was right where they were supposed to get us all of that One of the unique things about a fall of... One of the unique things about Apollo 15 was the fact that Dave Scott, the commander, wanted to do what was called a stand-up EVA as part of his mission Because this was a site nobody had ever been to and it had the mountains surrounding it, the real and a whole set of other things And we didn't know what the details, we landed here in 40 meter resolution images

And you know, that's like unbelievable And so once they got on the surface they actually opened the hatch after they put their suits on And then Dave Scott stood up on the top of the lunar module and described all the geology It was absolutely amazing and he loved it because he could really get these geological descriptions down And that helped us plan the extra vehicular activities There was a prepared plan because we kind of knew a lot of the major things but we needed to know whether there were blocks or whether the features looked like they could get to them and so on And that was a spectacular aspect of the Apollo 15 mission and Dave was a real geologist at that time And we got that actually, we know for certain that that came out from the training Because one of Dave's professors or teachers is Lee Silver and he always emphasized this whole thing from the beginning Get the big picture, he would turn it just first of all before you go down and look at anything at all or sample in it Get the big picture, see where you are, see what you're doing And I remember that when Dave suggested to the powers to be that he is going to stand up and look around after he is tired and landing after the huge day of activity And that he was just going to stand up and put down his suit and stand up and open up the hatch and look around and talk about this

And the powers to be were wild, what the hell is he wants to do this now for? Those geologists have gotten to him And they had and he did and it was a great job, it really was a very useful thing for him to do Because he figured out where he was, he described the whole setting with good scientific terminology And it's kind of assured that the mission is going to be right, he's going to get all what he's after And that he's going to do it in a sequence in his mind that he knows what he's after now, after he knows where he is In the general view that he's going to emphasize the details and do it well Now just quickly looking at this map, what was exciting about this landing site? What was it called? What was it exciting about it? Well this was the Hadley-Apponine site because of the Hadley-Rill and the Apponine Mountains And those are the two major goals to try to understand what these mountains were formed from Probably the Embryon Basin and then this Rill, what goes on in these rivers that are no longer carrying any fluid Some people thought they might be water, other people thought they might be lava channels

But they were gigantic compared to Earth lava channels, so those were the two major objectives of the mission And they were met very very successfully by different, the traverses out on the surface and collecting the materials The third goal was this rough cluster here, which was a set of craters formed by ejecta coming from a large crater to the north Crashing in here and excavating local materials, so we thought that by sampling this we could actually sample material from way far away And perhaps date it and that's in fact what happened? Where does he make the enormous site that's coming? That was done right here on the Apponine Front Can we meet that back as a culprit? Okay When they came, hold it Or Elba's head With traffic It's an effect?