NOVA; To the Moon; Interview with Thomas Joseph Kelly, aerospace engineer responsible for working on the Apollo Lunar Module, part 2 of 3

When we built the limbs, we knew we'd never see them again, because they couldn't re-enter the earth's atmosphere. So when they were gone, they were gone. That bothered me a little bit at first, but I soon forgot about it. And there really isn't that much difference whether you had the piece of it in some museum someday, or whether you had a predecessor unit that had never flown in the museum, which is what we have with the limbs. So that really wasn't the big issue. The big issue in my mind was, I wanted to be sure that lamb would do its job and bring those astronauts back safely. And that's where we put our concentration.

Now speaking of that, let's talk about the Apollo 11 landing, right after they landed on the lens. First of all, what was your reaction to that landing? And then, didn't they have a problem immediately? Apollo 11 was a very exciting mission for us, more exciting than we bargained for. I was supporting the mission as the head of the Grumman Technical Support Group, was located in a small windowless room right across the hole from the big mission control center that everybody in the world saw on TV. And that room was called the Space Craft Analysis Room. They had senior people there from Grumman for the lunar module and from North American for the command and service modules and senior NASA people. And we were there to help the NASA. If anything went wrong with the limb, we had to give them our opinion or our advice on how to resolve the problem. And there were a lot of these problems.

Some of them were pretty minor. They used to call them anomalies, anything that was different from normal performance. But what happened that night? Well, on the Apollo 11 landing, the powered part was pretty exciting, as everyone knows, because there was a momentary overload of the computer when it got both the landing radar signal and the rendezvous radar signal together, which it wasn't supposed to get. And it triggered an obscure program alarm, both in the in the limb, in space, and on the ground. Fortunately, a couple of the NASA flight controllers had been studying up on this list of program alarms. So they recognized this one right off the bat and they said ignore it, keep going. And it was all, it was

that fast. So that was pretty exciting. And then Armstrong had to take over manual control away from the computer because he saw boulders in front of them. And he had to steer it manually. The surface was not as benign as they originally thought it would be. So that was kind of exciting. And then we also edited out when the 32nd fuel remaining warning went off and they still weren't down yet, but they were very close. So they got down with about 20 seconds of fuel remaining. And we, we breathed the sigh of relief at that. But for me, it didn't last very long because I was looking at the, at the read-outs from the lamb. We had instrumentation that showed us in real time what was happening in the lamb pressures and temperatures and what have you. And all of a sudden we saw that

in a segment of fuel line or between the shut-off valve on the, on the top of the rocket engine, the decent rocket engine, and a heat exchanger. The pressure and temperature were going up very rapidly. We realized that what had happened was that a slug of fuel had frozen in the heat exchanger. It, it exchanged heat with very cold helium gas, which we used to pressurize the heat exchanger. So at the very tail end of the shut-off, a slug of solid fuel had formed. The liquid fuel had frozen solid and trapped pressure between the valve and the slug of ice. Now the pressure and temperature were building up then because the heat was soaking back from this very hot rocket engine. Now the reason we didn't

like that is because the fuel itself is a pretty unstable chemical. And if you heated it up much above 300 degrees Fahrenheit, it's liable to explode on you. And as we were watching, it was going through 200 and 225 and 250. It was going up very fast. And so we got very worried. The head NASA man there, George Law, the spacecraft manager, he came rushing into our room, which was highly unusual. And discussed this with me and asked me, what do you think we ought to do? And I was on the phone with my rocket experts for a couple of minutes. And we came up with a scheme. We said, we don't dare let it go because it may blow up. We had gotten the rocket supplier and some fuel experts on the phone and they

all concurred. They said it's too dangerous to let it get that hot. And so one of our guys, our propulsion leader came up with an idea. Let's burp the engine. He said, we'll have the astronaut flick the switch. They'll just crack that fuel valve open and then we'll shut it right away again. And it probably will hardly even move the limb because it'll just be a little burp of the rocket engine. Well, it sounded like a crazy scheme but we were kind of desperate at that point. How much time did you have to make your mind up? Well, at the rate the pressure was going up, we only had another couple of minutes before it was going to pass the limit that made us very nervous. Whether it would actually blow up then or not, we didn't know. So, I discussed it right on the spot there with George Law and he said, okay, let's do it.

So he got all of the capsule communicator who was the astronaut on the ground who could talk to the astronaut in space. And he was just about to tell him this procedure that we wanted them to do when Law and Behold, the whole problem went away by itself because by this time that line had gotten hot enough that it melted this slug of frozen fuel and boom, the pressure went down to zero. So, at that point, I wiped my frow and exchanged high fives with my companions in the room and my colleagues. And that's when I first realized that we really had landed on the moon. Okay, good. Did anybody suggest a boarding? Well, during this over-pressure episode, the possibility of a boarding was mentioned.

We could have aborted. I mean, we had a panic button and it would have separated the essence stage from the decent stage and off we would have gone, but nobody really wanted to do that. I mean, we all had enough concern about whether we were even right on this idea that it would explode if you got above a certain temperature that we weren't willing to sacrifice the whole mission on that kind of flimsy basis. As a flying vehicle, how did the astronauts feel about the limb as a flying vehicle? It's the most... I mean, it doesn't look like a flying vehicle, does it, Tom? Well, it doesn't look like an airplane, but it flew very well. In fact, on the very first man mission in Earth orbit, they called them the spider on that mission, and when they had

gone through the simulation of separating... they had separated from the decent stage, simulating the lift off from the moon. So, Jim McDivitt was flying this very lightweight, essence stage, and he loved it. He could whip it around and he said, this spider is really like a sports car, he said. This is some flying machine. So, they liked it. It flew very well, and they liked it on the landing maneuver, too. It was honest. It was easy to handle, and after they had been through simulator practice, they got very good at it. I mean, they set that thing down like a crate of eggs every time, very softly. So, we never compressed the big shock struts that we had built into the landing gear. Was any danger of not landing

at perfectly level? Oh, yes. That was one of the... Tell me that back. It was dangerous. The issue of landing was pretty complex, because first of all, we didn't know exactly what the surface was like, and secondly, there were so many variables. You had velocities, three directions, you had sideways, four and a half, and vertical, horizontal, and vertical velocities, and you didn't know what the slope of the surface was going to be. It could be sloped, and you didn't know whether it was going to be... That's great. I want to pick... Tom Kelly, one. Well, there were a lot of considerations and concerns in landing to them. It had a uniquely designed rocket engine, which was throttleable, so that you could vary the amount of thrust from 10% to 100%. You needed that in order to be able to null out the

velocity at touchdown, because you had to touch down at very low velocities, both your vertical velocity, which had to be less than 10 feet per second, and your horizontal velocities, either four and a half, those sideways, had to be less than 4 feet per second. So you had to get within a narrow velocity box. We didn't know much about the surface itself, and we were particularly concerned about the hazards of tipping over, because with the one-sixth gravity on the moon, all that's holding you down is one-sixth of Earth's gravitational force. So if you were to land on a downhill slope, for example, and come sliding downhill, and then hit a boulder, it could tip you over. At least that was our concern. So in our

calculations and in our computer simulations, we concocted all sorts of worst-case landing scenarios. One of them specifically had you going down at the maximum 10 degree downhill slope on ice, and then hitting a solid curve to make sure we wouldn't tip over under those conditions. That's why the landing gear was spread so widely. It had such a wide tread on it was to discourage tip over. So it was a tricky problem. Now let's talk about when it really was a hero, the land in Apollo 13. When did you first hear that the Apollo 13 spacecraft was having a problem? What did you find when you got, what time did you get into work and what did you find when you got there? By the time Apollo 13 was launched, that was to be the third lunar landing. I had already supported the first two lunar

landing missions and everything went quite well. I had been given a year up at MIT as a Sloan Fellow by my company, and I was going back and supporting these missions from there. For Apollo 13, they decided, gee, you don't need to come back for this. Everything is going along so well. I was up and bossed at the time of the Apollo 13 mission, and I got a phone call at about midnight from a colleague of mine, and he said, hey Tom, did you hear about Apollo? And he said, what? He said, turn on the radio. Apollo was in trouble. And then he said, meet me down at Logan Airport at 130. They're sending a light plane up for us to get us down to Bethpage, which was the Grumman home factory. So sure enough, I went down

there and Howard Wright, my colleague, and I flew together on a clear April night, and knowing our fingernails as we went, because we were, by this time, well aware of what had happened on Apollo 13. The oxygen tank had blown up in the service module, and knocked out the second oxygen tank. So the command and service modules had basically no oxygen for the crew. And they had to go into the limb. That was their only recourse. What did you find when you got to the back of the crew? So I arrived at Bethpage Airport at about three o'clock in the morning, and headed right for the mission support room that we had

set up there. And the first thing that I saw was just a steady stream of people coming into work. I mean, it was 3 a.m., but it looked more like the start of the normal work day at 8 a.m. And most of these people hadn't been asked to come in. They had just heard about the problem, and they just came in to see if they could help. So I got into the mission support room with my colleague Howard, and we talked to our folks who were on duty there, and we assessed the situation as quickly as we could. It was obvious the first thing we had to determine was how long the limb could last supporting three crew members instead of two, given the amount of consumables that had had water, and electric power, and oxygen primarily. Where did your numbers tell you? My numbers showed that the most critical

component was electric power. It was in very short supply, and before very long we were convinced that we were going to have to shut down just about everything in the limb, even the gyro platform, which was a very undesirable thing to do because we didn't know how we were going to get it realigned later on in order to do the reentry maneuver at the end of the mission. But it just consumed too much power. We were going to run out of power at the rate we were going. So we started taking a very firm line with the NASA folks. John Aaron and his people down there started running simulations with us. We got the serial numbers of every major component that consumed power or consumed water in the limb so that we wouldn't

use averages. We dug out the test records on that particular piece to see maybe this one was a little lower power consumer than average, and maybe we can squeeze a little bit here and a little bit there. We turned on all the suppliers all over the country and got them to run special tests. What happens if you put low voltage into this unit down to 10% low or what happened? So they set up tests and in some cases we said, yeah, it's okay, you can do that. So we'll short-change the voltage on some of these items. So there was a tremendous amount of work that was needed in a short period of time. Meanwhile, the NASA people were wrestling with the issue of what trajectories to fly and how long it would take us to get back. So we had to make these two ends come together. We were

figuring out how long the limb could last and NASA is figuring out how long it's going to take to get back. And we did meet with a selected trajectory that was going to take about a little over two days, two and a quarter days. What did you think when you heard that? I thought at that point that we were okay. When I heard that they could get back in about two and a quarter days and looking at what we could see, it looked okay except we had to concoct pretty quick away of realigning that platform so that they would know where they were when it got to be time for reentry. Now the other problem that developed when we shut down all this power was it got very cold inside the limb and the astronauts were very uncomfortable. In fact it was unhealthy. What we didn't know was that Fred Hayes had an infection so he was running a temperature.

We didn't actually know that but he was in very bad shape sitting there shivering in about 46 degrees Fahrenheit temperature inside that cabin. It was rough. As much as you loved the limb, you couldn't imagine spending that much time in it, I'm sure. Well not in a light flight suit without any heat. I think that was the problem. The other thing that we had completely forgotten was the lithium hydroxide requirement. This was the lithium hydroxide was used to remove carbon dioxide from the atmosphere that the crew exhaled and with three crew members on board, LEM for two and a half days, we didn't have enough LEM lithium hydroxide. Now this lithium hydroxide came in replaceable canisters and unfortunately ours were cylindrical and the ones on the command module were rectangular. So it was literally

a square pegging around hole. It wouldn't fit a group down at NASA headed by Ed Smiley and with Grumman and Hamilton standard engineers participating came up with a very ingenious fix that the astronauts could do with the materials they had on board, cardboard and tape and some of the hoses from the spacesuits and in very short order they worked up a fix for that problem. Now when did you first think about using the LEM as a lifeboat in an emergency situation that had come up prior to 13, hadn't it? Yes, the idea of using the LEM as a lifeboat, sorry, one more roller would be...