NOVA; To the Moon; Interview with Buzz Aldrin, engineer and astronaut, and lunar module pilot on Apollo 11, part 3 of 4

Decicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicicici Well, we're proceeding with the descent and we're kind of yod over so that we're looking at the ground and we're going with our feet first, which means that the ground is moving

along this way as our feet are moving this way. So we're watching landmarks going by and I had no means of really measuring the landmarks to compare them with where we should be so I didn't spend a lot of time trying to identify them because I could see that that was not going to be part of my job. My job was more the numbers and the time and the altitude and comparing the two computers. He still had a grid and so he could be the observer and he could time the progression of different craters as they went along. And it was some point maybe three or four minutes into the descent when he made an observation that looks like we may be a little bit long and I thought, you know, how can he possibly suspect that but it turned out that we were a little bit long. But I'm not sure whether it was because of that particular observation, he surprises

me a number of times when he comes up with an observation, turns out later to be correct. But about that time we needed to yaw around so that we could then get ready to pitch forward in that part of the trajectory and as soon as you yaw around then the landing radar can begin to acquire the surface. And as it began to feed information as to what the altitude and altitude rate were the computer compared this with what it had and it came up with a difference and then it would begin to narrow that difference down indicating that you were closing in on the solution and this number was displayed to us and as soon as we got the lock on it began to do this but about that time as I was watching this happen where we had a computer alarm come on which meant that the numbers that I was looking at on the three different registers

usually x, y and z or some other numbers altitude, altitude rate and delta, delta p or whatever it was for the radar. We no longer had these numbers going with time but we had this alarm in a flashing light. So it interrupted our monitoring of the trajectory in 1201 or 1202 didn't mean anything to either one of us. Now over here in the bottom of our filing cabinet we had a big dictionary that you could look those things up but during the descent we weren't about to pick that up as long as we had communication so we asked the ground what was the meaning of this and after they looked up and tried to understand what was causing this they could see evidently that the time that the computer took to go around polling the different things that it was going to be doing in each cycle and those cycles were maybe a fraction of a second it would be polling

these different ones performing the different tasks. It was supposed to be done within a certain time and then of course there was a significant pad of time so it would normally only take maybe 20, 30% of the time to do that but it got a little bit above this and they set a gate on this and when it exceeded that gate then it caused the alarm and the reason after the fact was because it was processing rendezvous radar data and landing radar data at the same time I'm not sure whether we were still locked on to Mike Collins and his transponder but the MIT people didn't figure that anyone would be doing both of these at the same time so they set that gate a little bit lower well anyway the caution light came on we didn't know what it was and after some number of seconds we got the call that it was okay because it just interrupted and diverted

our attention from what we were doing for a period of time then we could go back and catch up where we were and as long as this didn't keep happening too frequently why we could proceed on and so that's what they were watching how frequently would these alarms come on and I guess in retrospect I would have thought there might have been six or seven maybe there were fewer or maybe there were more I'm not sure which but we had both 1201 and 1202 once we got down to about a thousand feet that wasn't a problem anymore and at 500 feet Neil took over manually and controlled the craft and then began to divert it from where we were going to land a little bit long so the computer alarm was one of concern for the people on the ground and it was some concern for us because it diverted our attention but it really was not a serious problem when did you did Neil ever communicate to you

he said you knew you're going a little long but when did you really get a sense that you were definitely long you were not coming down in the footprint that you had planted oh I don't think I don't think I understood that or he understood that we there the landing site that we picked was such that there wasn't any characteristic landmark that you could identify and then close vicinity it was beyond those so it was just a sense of question of well if you saw something that was on the map and then the landing was further away but again that was not part of my challenge to understand those things that was the person who could do something about it who was looking out the window if I was expected to do that then I should have been looking out the window but that would have diverted my attention from the abort guidance and the primary guidance and all the other instruments so we had to split the tasks and there wasn't much point in paying attention to the other guy's task and that was Neil's job Neil's job was flying the thing and so you know when

you look at it why would you for example want to train both crew members to fly the manual landing in a dangerous machine like the lunar landing training vehicle that Neil had to bail out of well if it's not for any useful purpose why train people and doing that so if you understand those things and then you say well no I don't really see why I need to fly that then people say well you don't want to fly because you're afraid of it well that's not the truth at all you take risks that are appropriate well at a certain point though you knew you were coming down on fuel you knew you were getting lower than you wanted to yeah but we didn't have anything to compare it with we'd done training missions many times they had never given us a training mission where we were coming in and about to land but we didn't quite have enough fuel to be able to do it now you say well how could you possibly train for a lunar landing mission and not have one of those cases well

it was not ours to try and say well hey wait a minute you simulation guys why don't you give us one where we can't quite make it you know this is not the way you played the game okay but good you took me before when we're talking about moonshot he took me down to those last few seconds you were getting a little kind of like let's get this thing down so take me down to the last few seconds the Neil is kind of searching around looking for a place to put it down with your little bit of anxiety a little concern on your part about where you were going to get that landing and when you were going to get it down not fear but just what's going on well it's really hard to compare the recollections of the actual mission of course you could play that back again and see an examine all the different parts but it just seemed to me as though whatever he was doing I couldn't help him out very much in any way other than giving him the numbers that he didn't need to look down at the computer because he was concentrating on out the window but I could see that that

we'd leveled off and we started a climb and we went back down again I didn't know why but I could also see that we'd been doing this for you know a good number of seconds and then when 60 seconds and the light came on and we were still not real close to the ground where maybe 120 feet I forget exactly what it was then I guess I was getting a little more concerned but what could I do could I say hey Neil hurry up get it on the ground that would just excite him a little bit more so I couldn't say that all I could do was trying you know just give him my encouragement silent encouragement this body English in a way that he couldn't quite understand and it's really hard to say when you're that concerned because you know you're doing something for the first time anyway so you've got a lot of concern about it and you're just kind of hoping that it's going to work out right and at the call out of 30 seconds which we didn't have any indication of the fuel level

at that point we knew that it was ticking away somewhere and the fuel was getting less and less but the ground had a better indication so they called out 36 but we were maybe 15 feet above the ground and just a few seconds we were on the ground then. Well the moment of touchdown we had to contact light come on and we didn't go back up in the air so I knew that we had the probe which was about five feet from the landing gear had been moved enough to cause the contact light to turn on so what we wanted to do at that point was to stop the engine because you don't want to land and keep the engine burning because you might pop back up into the air so I called out contact light engine stop and then once you do that you don't want to keep firing the jets so you have to hit the hand controller and that's why I call it ACA at a detent which means you just hit the hand controller which would stop the jets from firing and then you'd go and do some

of the other shutdown procedures. Of course what you're waiting for in us for seconds is in a board right do we have to get out of here right away? No once you stop the engine you're there. In any landing where you have a vertical thrust like a helicopter or rocket thrusting as you're coming down there's a combination of conditions where if the engine stops you have a certain descent rate maybe or maybe you're just hovering the engine stops you're going to hit the ground if you don't do anything and then there are a number of seconds before you can take some action whether it's with that engine or with the SN engine to make the abort cycle and separate and do all those things that take fractions of a second to happen and by the time those those correct the error of the descent going down to one going back

up again you may hit the ground so you know these are situations that are going to occur close to the ground in any normal situation and they can happen I mean the chances of them happening are greater if you're running low on fuel because if you run out of fuel right while you're in that place you may hit the ground before you can get the SN engine going but then again if you if you run out of fuel and you're only five feet above the surface you don't want to abort because you're not going to hit hard enough to make any difference it's going to be a good successful landing. Now when you actually landed there was a lot of dust kicked up were you surprised by the amount of dust that kicked up I thought I'd recollected somebody saying you know a lot more than. No as the as the as the as the lander got closer to the surface there was an obscuration of the little rocks that were sitting because there was a fanning outward with with the sun coming from behind us causing shadows

and that fanning outward was the dust being blown out it didn't billow up because it would only billow up if there was an atmosphere so it was going straight out and it was obscuring the surface like a very thin layer of fog or dust and you had no idea how deep that was but it couldn't have been more than six inches or a foot maybe so so that picking up some dust is what I what I said over the air as I could see the shadow of the probe in the back from the sun I could see the shadow of that coming closer and closer and that meant that we were five six feet and it will be seven or eight feet above the surface so I could see picking up a shadow and then dust and then I knew we were very close and then contact light engine stop. No worries of Thomas Gold's you know 30 feet of lunar dust that was going to swallow the

spacecraft I take it. Well Thomas Gold would have been very famous had we sunk in and you know people who are doomsday predictors are motivated by the glory they will get if the doomsday occurs and they happen to be predicting it right but if it doesn't occur then people will remember them anyway so it's a pretty good gamble to claim something dangerous is going to happen if it if it doesn't happen they forget about it but if it if it does you're the big predictor. Now hello did it take you once you land did you I mean come on you're a human being did you look out and say wow this is really something I know you're very busy with all what was going on in the spacecraft but when did it finally dawn on you then hey we're here we're on the surface of the moon we did it as soon as we touched down I knew we'd done it but I knew that there were certain discrete times after the nominal touchdown if something was wrong you don't want to abort right away you want to wait until this discrete time because they're more favorable

rendezvous conditions and after about two minutes then it's too late really because if you were to lift off after two minutes after the normal landing my Collins is going round and round and he's too far ahead for you to catch up to him in a reasonable time and he's going to have to do some other maneuvers so that you can catch up with him so those first couple of minutes are very crucial to look around and see if everything is okay and then hope that the earth is measuring everything the status of all your pressure systems and your tanks and your electrical systems because if you do have to abort you should do it right away and I felt that that was a fairly critical time so it surprised me if that during that time Neil chose to make make the call Houston train quality base the eagle has landed it surprised me a little bit because we'd never trained to do that because we didn't want to tell them back in the simulators and the training

what we were going to say after we landed and I expected he would wait until we'd been there so that we could monitor those things but you know it's something that is a surprise but then you understand well that's the way you should do it you should call right away things like that did you two acknowledge it at all to each other hey you know after all this tension we're here you and Neil well we looked at each other and I pated him on the back a little bit I that was about the extent of it we knew we were there we didn't have to we smiled at each other I think that was about the extent of it gotta be a hell of a moment though it sure is there's nothing you can say do really they could live up to the the emotion of the moment everything would be an understatement no matter what you do would be understating the whole thing we anxious to get out how long did it finally take you till you descended the from the lend yourself what

took an interminable time until we went through we we didn't have a timeline specifically because the way the flight plan was written we were going to rest and then go out later well we decided not to do that so we had a lot of time because there wasn't any really concrete sequence of times that we had to live up to so we just took our time and felt we would if we were more relaxed in what we did we'd be less likely to to omit something or to make some kind of a mistake but once we're once we landed on the surface for the next two hours everything was geared toward the potential launch one orbit later for Mike coming around because if we did have a problem after that two minutes of initial abort then we would have to get ready to abort one orbit later

as he came around and that was something that I had inserted into the flight plan maybe a year ahead in some of the before crews were ever announced Jack Schmidt and I and maybe a few others looked at different things that we could do and I suggested that maybe the best thing you should do right after you got on the surface is get ready to leave at the earliest normal opportunity which was one orbit later and and here was an example that I felt that you know it's probably been four or five days since you've trained on those launch procedures now is a good opportunity to do a dress rehearsal as if you are going to leave when you know that nothing's wrong so you probably aren't so you just go through the exercise none of the crews later did that and I think that they should have because but it was another example of not invented here a crew comes along and they look at what the others do and they say well now we don't have to do that we'll do it

our way you know so how long so you waited two hours before you for one meal then we started getting ready and that took two or three hours I think before we were ready to go outside and then it was a question of you know he went out he had a number of things to do we sent the camera down he had to pick up the contingency sample and then it was my turn to go down good how much footage we asked cut for a second you referred to it as magnificent desolation I mean your description of the moon what was it like what was it like when you stepped on it were you surprised by the surface what described it to me well the first thing that I wanted to do when I got on the surface was to hold on and to just sort of bounce around and check the mobility that I had and then let go and see what the footing was like and and all that took was maybe a 30 seconds or a minute to to feel that I knew how to move around with with great confidence and that's all the later crews really needed to do so I was doing that for my benefit but for their benefit too and later

on in the space walk outside when I jumped around and pranced around again I was doing that for the benefit of the people back on earth to see and to measure and see what the mobility was like so that it would give something in addition to our verbal description of observations when we got back the things that we did on that first mission I felt were done to make later missions more successful so we would pioneer we would look and see what the condition of the lander was take pictures of it so that later on the the people wouldn't have to spend the time doing that our mission really was to put out some simple experiments the laser reflector the passive size thermometer to verify that the leveling devices that the antennas worked to do some quick sampling of the surface because our lander was heavier than the later landers we didn't have

the room for the consumables or the margin to be able to stay out to go out twice for example or to stay out even longer and whatever the flight plan and the engineers decided our mission was going to be and how many hours we could stay out that was it there wasn't any point and say well hey let's change that so we can instead of staying out two and a half hours that we can stay out four hours gee the guys did decalculations and they said that's that's what you could do so that's what we we stuck with did you feel it there was enough science too much science