NASA Johnson Space Center
Oral History Project
Edited Oral History Transcript
Interviewed by Kevin Rusnak
10 April 2001
Rusnak: Today is April th, 2001. This interview with Bob Carlton
is being conducted in the offices of the Signal Corporation in Houston,
Texas, for the Johnson Space Center Oral History Project. Interviewer
is Kevin Rusnak, assisted by Sandra Johnson and Carol Butler.
I’d like to thank you for joining us once again this morning.
It’s my pleasure.
Last time we talked a lot about the Gemini Program, and this time
we’re going to discuss Apollo. So if you could explain how you
made the transition from one program into the other, what sort of
differences it meant to mission control, learning these systems for
you, creating new mission rules, that sort of thing.
Okay. Pick up at the end of Gemini, and transition through the end
of Apollo, and then describe Apollo, I presume.
As we came to the end of the Gemini Program, it had been fast and
furious. It was, I guess, a period of learning for most of us newcomers
to NASA. We still weren’t totally trained and didn’t totally
understand what this business of flight control was all about, but
we were beginning to glean it. We had that team of flight controllers
who had now gone through several missions, and a lot of them had been
through two programs, had been through the Mercury Program and transitioned
into Gemini, and now they were moving on into Apollo.
The team of guys that had been flying missions all this time were
too busy up to that time to have even thought about Apollo. In parallel
with Gemini, there were other guys who had been working on Apollo
all of that time. I’m not sure exactly where it started. We
were sort of oblivious to its presence. They were over in another
part of the building. The guys in flight control that had been following
the Apollo came into it probably in its inception when they first
started designing it. They looked over our shoulder, and they were
like us in Gemini, newcomers to the game and probably like I was when
I first hired into NASA at Gemini. “What is this all about?”
They had been over and sat in some of the missions. You don’t
really learn it by looking over the shoulder. I can’t explain
that, but you don’t appreciate it until you got in the midst
of it. A lot of that stuff just flies over your head and you just
don’t appreciate what’s going on. It’s simple. So
they had been doing that for several years and mostly, probably, were
just totally immersed in trying to watch the Apollo design progress
and to influence it so it would be easy to operate.
When we came to the end of the program, there were two or three things
that I’d call a transition and in the nature of transition.
One thing was that we had been so immersed in Gemini, we didn’t
even know what the Apollo hardware looked like, or the spacecraft
looked like. Occasionally, you’d see a picture on the wall,
but it didn’t even have a gleam, or inkling, of what was there
and how it worked and the systems in it. So there was a brand-new
set of spacecraft systems for us to learn.
At the same time, there was a group of people who were our brethren
in the flight control game. Maybe you ought to let me diverge on a
tangent here just a moment.
There is a rapport among the flight controllers that I’m sure
you’ve observed as you’ve interviewed them and talked
to them, that I suspect is sort of unique. Maybe a few other occupations
develop that rapport. I’ve often wondered about it. It’s
a sense of—I don’t know that “brotherhood”
is the right word—“camaraderie” is the right word.
I observed it in a few other occupations that maybe talking about
it there would give you a better sense of what I’m talking about
amongst flight controllers. I notice among policemen, if one is hurt,
they all gather and rally around and feel the sense of hurt. I’ve
often wondered about that. I kind of think what it is, is when you
face a very strong common adversarial situation, it draws you closer
together. I see that same sort of thing exhibited in the combat people
that have been in the service and hear them come back and talk about
the experiences they went through together and talked about some of
the things they did for each other. Some of them would give their
lives for each other.
The flight control team, as they’re planning a mission and trying
to get it all together and accomplish its objectives, you get a sense
that we’re all doing this and everybody’s doing it together.
You see it in the football teams here. It’s a team effort. That
team effort develops a camaraderie that’s probably there with
them for life, assuming it even stronger when there’s an element
of risk and danger involved in it. In our case, the danger wasn’t
to us, but it was with our cohorts, the astronauts, who were in orbit.
We felt a tremendous sense of responsibility. It [would have] broke
our hearts if one of them had been hurt due to our faults. So there
is a common sense that above all else, we must not let a fellow space
traveler here be hurt.
But when you went through trials and stresses and problems like Apollo
13 and others, every mission had a series of little traumas that weren’t
of the magnitude of the 13, but still had the potential in it before
they got corrected, it built a bond that’s difficult for me
to describe. But I see it even today. I can walk in a room somewhere
and see one of my fellow flight controllers, and it don’t matter,
I’ll just automatically be aware of him the instant I walk in,
and I’ll see his awareness of me.
Sometimes you walk in a meeting, I recall one time walking in a meeting
years later, I’d left flight control and was working with the
Air Force. The Air Force sent me over to a meeting where a new mission
was being reviewed, and [Eugene F.] Kranz and Don [Donald R.] Puddy
were sitting up at the table, chairing this meeting. They had a bunch
of new flight controllers. A young lady was up there briefing them
and going on. I sat down next to Carl [B.] Shelley, who was one of
our old flight controllers, and we exchanged greetings. I saw Don
and Kranz look at me, and one of them nudged the other one, look back
there, and their eyes lit up. We acknowledged each other.
This young lady was going through mission rules, and it took me a
while to realize this is a female flight controller. Now, this sounds
like a male chauvinistic, so you ladies don’t get upset. In
our time, there was one female flight controller, Cynthia [F.] Wells.
No, it wasn’t Cynthia Wells. Cynthia was the second one. There
was another one. I forget her name, but she ended up going down to
Houston to become a councilman or something like that, had a lot of
voters. But most of us were males in that day.
Anyway, when I walked in, this young lady was briefing them, and it
was a few instances before I realized, “She’s talking
like she’s a flight controller.” I nudged Carl, and I
said, “Carl, is she a flight controller?” He grinned.
Well, I looked up at the table, and Kranz had nudged Puddy, and they
were just laughing. Both of them, they were waiting for me, my reaction,
to see what, before I finally woke up to this is a change in the organization,
progress. But the camaraderie there is what I was trying to get a
Now let me come back from that tangent. We were getting ready to go
into Apollo. We were not only learning the vehicle. We had a new team
of guys that were interleaved. It was a great transition to bring,
in our case, in the LM [lunar module], Jim [James E.] Hannigan had
a group of guys that had a lot of Air Force troops with him and a
lot of contractors with him, Grumman [Aircraft Engineering Corp.]
people and a lot of NASA people with him. I forget how many there
were, but a pretty good organization of flight control people, who
had not been involved in the missions other than just watch it happening.
So the effort was to meld the two teams together, the ones that had
been flying that don’t know a thing about LM and the ones that
knew everything about LM but don’t know a thing about flying,
and to get them up to speed and weld together a flight control team
that would then support the Apollo. So we had a massive reorganization,
sprinkling them all together. Jim Hannigan became our branch chief,
and we formed a new branch. The ones in the branch, we divided the
branch up similar to the way we have the control team in the MOCR
[Mission Operations Control Room] and in the Mission Control Center.
Each bird had basically two groups of people following it. We split
the bird in two, if you will, systems-wise. Don Puddy was part of
Hannigan’s group of guys. He was a young Air Force guy that
had come out of the Air Force and joined NASA. He ended up with one
section in this branch. Jim Hannigan was the branch chief when they
worked LM and prior to while we were off in Gemini and he was with
the Apollo following the LM. I had the other section, which was the
guidance and control.
In his section, we took some of the Gemini electrical people and put
them over under Don and sprinkled them in his section. Then Jim sprinkled
some of the people who’d been following the guidance control
systems into my section. Then I kept some of the guys who had been
flying Gemini flights with me, John [A.] Wegener and Hal [Harold A.]
Loden and Paul [D.] Nering.
The transition there was kind of rocky when we first started. There
was sort of a growing period, I guess you’d say. Part of it
was getting to know each other. Part of it was overcoming some psychological
barriers that you had naturally built up and you didn’t dream
were there until you got to working together. One barrier we had to
overcome was those who had flight experience on the console sort of
disdained the ones who’d been back here on the desk and didn’t
know a thing about flight controlling. It made me think a little bit
of my own experience when I came in as a Gemini flight controller,
a newcomer, didn’t know a thing about flight controlling.
Some of the guys that worked with me, Ed [Edward L.] Dunbar [Jr.],
I remember, was one that worked with us. He was a Philco troop that
had been back in Mercury. Their favorite expression was “Well,
now back in Mercury, we did so and so.” The implication is,
“You just don’t know a thing about how this works.”
I got so sick of hearing that. [Laughter] I can remember some of the
guys telling Ed, “Ed, we don’t give a crap what you did
back in Mercury. This is a new program.” Well, I’m sure
the LM troops felt the same way about us. “In Gemini, now we
But as we worked together trying to plan the new missions together,
the new perspective evolved us, and they challenged us, “Why
are you doing it this way?” Well, even though you were impatient
with them for saying that, we’ve done it and this is best, still
they say why, you’ve got to stop and think, “Now, why
are we?” Or if they say, “Why don’t you do it this
way?” you’ve got to answer the question. In answering
the question, you begin to realize there’s a different way.
We done it one way, but there’s another. So we had, I guess,
you’d say an evolution take place as the new blood poured into
We had a different psychological barrier or hurdle we had to overcome.
The guys that had been on the LM and understood the LM and been in
the design of it, if we came in and looked at something and criticized
“Why did you let them design it this way?” Well, there
was that same defensiveness. But they had to answer the question.
They were the experts on the LM. We were the experts on flight controlling.
Each one felt like, a little bit, “This is my turf. You do it
like I say.” So they had to kind of get over that.
Another thing they had to get over, and this was most especially difficult
for the Grumman [Aircraft Engineering Corp.], the contractors, the
way they had worked, prior to coming into our outfit, was here’s
the LM being built. Grumman had sent this team of guys down to assist
the young NASA green-bean troops, who were younger than the contractors,
[the] old mature guys. Really old, they were in their early thirties.
The NASA guys were young. They were in their twenties. The contractors
were the experts on the systems, so they had a sort of a relationship
with these green-bean NASA troops. “I’m a senior engineer
and understand. You come to me. I understand the whole thing.”
Well, when they came to us, we didn’t work that way. We expected
every flight controller to be intimately familiar with his spacecraft.
More than that, they weren’t dealing with a young NASA twenty-year-old
when they came in to us. I was more mature, like I say, I was essentially
their own age and pretty domineering in the way I run the outfit.
That gave them a lot of heartburn. Though when I asked them to do
that, I accept them as flight controllers and determined to make flight
controllers out of them, and I didn’t realize their ignorance
in flight controlling. I acknowledged their expertise in their knowledge
of the LM, but they were ignorant in flight controlling. But they
hated to take on this role of ignorance.
So it was a transition for them, to suddenly not be the all-knowing
senior person in the outfit. It also was a transition for them to
have to be completely under the authority of a young NASA troop. Even
though I was approximately their age, I was still. So we went through
a lot of growing pains there.
But, gradually, as we kept our focus on “Here’s what we’re
trying to do and here’s the mission,” that teamwork came
to the forefront and they evolved into a close-knit team. Even today
they are part of the flight control team.
We had a mixture of people, contractors that came from Grumman, we
had Philco contractors, like Dunbar and some of the others, that went
out to the remote sites. Ed [Edward I.] Fendell, there was just a
raft of them. They were good people. We had Air Force and other servicemen
that came in and joined with us. Then we had the NASA corps. I don’t
know what the ratio of people would be. I would guess NASA people
were no more than a third of the total team.
One unique thing about it was they all worked together close as a
team. There was a teamwork there that took place that you just sort
of before you knew it, you were doing it. It made you sort of subvert
this human tendency to, “I’m the hero.” It was,
“Boy, if we don’t all do our job together, this is not
going to work.”
When you listen to the tape later and you hear the mission taking
place, you can perceive that. If you’re listening to what’s
happening, you’ll hear one guy say here’s so-and-so and
so-and-so, and another guy from another organization, “I got
that, Flight.” He’s waiting on the information, and the
teamwork back and forth between them all and the way they work together
as a team will come through to you, I think.
So we were transitioning and getting ready to go into Apollo. At that
time, also the Mission Control Center was still transitioning. It
had a brand-new system to support Apollo. In the early missions, that
thing was still growing, and it had some horrible bugs. Every time
you sat down to do a simulation, they’d have improved it a whole
lot since the last time, so the improvements just made it difficult
to keep up with what the ground system was. It was growing and changing.
Each mission, we put in requirements and said, “Now, this is
what we’d like to have. This is the way we want the displays
to look, and here’s the way we want the event lights to be driven,
and here’s the parameters. We want a strip chart recorder, and
here’s the data rate we want coming in the door.”
They’d say, “We just can’t get it. We can give you
this much.” So every time you sat down on the console, you didn’t
know what you had. Sometimes they’d work themselves to the bone,
and you’d have something you didn’t expect. Other times,
you was expecting something that wasn’t there. “That’ll
be the next mission.”
Later on, it was a chore. You’d sit down and you’d have
a configuration. Mostly it was software. You’d have a configuration
that supported this mission, but when you reached a point of maturity
and they had tested it, then they didn’t want to change it anymore.
You had it verified and it was supporting the mission, you don’t
want people in there messing with it or they might put a bug in it
that will mess you up in the flight.
So you reached a point where you froze this configuration, but you
also, at the same time, you would be training for the next mission,
running simulations on it. So you’d go in and with this mission’s
configuration and train today, and tomorrow you might run a sim on
the next mission’s configuration and had a bunch of improvements.
Then you’d get back the next day to this mission, and your brain
would get mixed up. “Now is this event light working or not
working? Is this display? What are these parameters on here? Oh, that’s
the next mission. Oh, I didn’t think they’d get that to
two more missions.” It was hard to keep up with, and it was
frustrating. That was a big frustration. Toward the end of Apollo,
that settled down and we began to settle down, steady state, and then
there were more incremental changes. But in the front end of the program,
there were some just massive changes taking place.
Another thing that took place was the transition as we, somewhere
along the time, and I forget what mission it was, we suddenly had
all the data flowing in to the control center. We got a taste of that
when the bird left in the lunar missions. As the bird left the Earth
and went toward the Moon, it was continuous contact with it. We had
these big antennas that could see to the Moon and all the way, and
the bird was somewhere between here and there. No matter how the Earth
rotated around, one of these three big antennas could see it.
They could flow real time, what we call real time, data to the control
center. By “real time,” I mean like it’s the total
data stream flowing to you—not actually the total, because it
flowed through a bottleneck. The data lines that came from those sites
were one or two kilobits of data. The data coming out of the bird
was probably a hundred times, I don’t know exactly, maybe a
thousand times more than that, so you had to select the particular
For example, the thruster firings, an RCS [reaction control system]
thruster that controlled attitude, the thruster could fire for about
ten milliseconds, a minimum burst. If you just had a small amount
of error, you… want to turn a thruster on that small amount
of time. If you had a big torque you was counteracting, or the astronaut
was doing a maneuver, then you’d turn a thruster on, and this
was automatic in the system, of course. But you’d turn it on
for a bigger period of time, maybe a two-second burn. Well, to get
those teeny-weeny burns, you had the telemetry downlink that parameter
showing you thrust chamber and RCS thruster at maybe a hundred times
a second. But when it got to the ground, you couldn’t flow that
much data to the control center, so you repacked that information
and you put that bit in there and you turned it on. If the thruster
had fired in the last two seconds, it turned the bit on and it stayed
on. At the end of two seconds, it turned it off, and they sampled
the bird again, the data stream, and if it was still on, they reset
the bit and you got another. It showed it.
So what came down at a hundred times a second I saw on the console
as once every two seconds. Sometimes that took a lot of planning to
know which parameters didn’t make any difference and which parameters
is important to have a higher sample rate done. We went through a
lot of learning on that.
Some parameters like the temperature in a tank is a very slow-moving
thing. You get in the sunshine, and the sun warms it up, and it begins
to creep upwards. Well, once a second, you can go once every five
minutes and keep up with that temperature. You get a thruster firing
every ten milliseconds, and you’ve got to have it fast. That
bit, we had some learning and a learning curve there, too, learn how
to live with this choke-down data flow coming from the remote sites
to the control center.
Then we had limitations in the control center on the TV. It updated
once a second. So it didn’t matter how fast it come into the
control center, it was going to get updated one sample per second
on your TV monitor. To get around that, some parameters like the RCS
thruster firings, we’d put them on an event light. They had
drivers downstairs, and it would drive that event light at whatever
sample rate it came in off the pipe. This data flow coming in, I call
it the pipe.
We had a lot of arguments about that. We had two pipes. That was a
big, big battle that took place in the early part. The sample rate
just was not sufficient with one. I forget how much flow was in one,
1-point-something kilobits, and we filed for a second line, data line,
and it got us up to 2-point-something kilobits. Today, that’s
teletype counting data flow.
But it was expensive to bring that second data line in. We had a big,
big battle over that, and finally John [D.] Hodge, our chief of Flight
Control Division, was the one that made the decision, finally. But
it was a big strong battle. He didn’t want to buy the extra
cost it took to have that line brought in. But finally he acquiesced
So as we went through those growing pains, we got ourselves prepared
and began to do simulations. The simulator itself, that’s a
complex system. I hope you talk to some simulator guys. They’ll
tell you that was not a simple thing. I mean, they had to simulate
this vehicle, LM vehicle, that looked to us on the console just like
the real LM, and they did a fantastic job of it. Had to simulate the
dynamics of it going to the Moon, and if we did a burn, it had to
transition itself into the dynamics that we saw changed the thrust
vectors and changed the flight vectors of the ephemeris, and they
had to do it in such a way that it looked real to us. And it did.
It looked so real, that after you got through and thought back on
the mission, it was difficult to separate in your mind what happened
in sims and the real mission, with the exception of a few.
The Apollo landings stuck in your mind pretty strong. But most of
your sims, the on-orbit stuff, you get it confused. You think back
and you’ll remember something, “That was a sim. That didn’t
happen.” Some of the little incidents with people doing things,
that was a sim that didn’t really happen.
The one example of an incident, and actually this was back in Gemini,
but it’s an incident that illustrates that point. It seems like
a real mission to me, but I think it was in a sim. I know it was in
a sim. We were going to do a burn, and we did that manually controlled
from the ground. It’s a very, very short burn, like at one-and-a-half
seconds or something like that. And we did it on time. Started a stopwatch.
So when we did the burn, I had the stopwatch in my hand. I got one
button on the engine and one button to fire the engine, one button
to stop the engine. So the sequence has got to be fast, and it’s
got to be right. Now, what am I going to do? I’m going to arm
and I’m going to fire and start the stopwatch at the same time.
Then after so many seconds, I’m going to stop the stopwatch
and punch the stop button. Well, I got mixed up. Arm, fire, and instead
of starting the stopwatch, I hit the stop.
Well, there was a little light come on. The command’s received
by the bird. I hit arm, and that light went up. I hit the fire, and
that light went up. About the time I hit that, I realized I done a
wrong thing. I thought maybe it didn’t take. Ten eternities
later, that big light came on. Engine stopped. I thought, “Oh,
what have I done? I don’t know what I did.”
About that time my SSR [Staff Support Room], I hear it in my ear,
“Bob, the engine shut off.” He couldn’t see that
I’d sent the command.
Shortly after that, the FIDO [Flight Dynamics Officer] down there
says, I hear him tell flight, he says, “Flight,” he says,
“we don’t indicate that we’re burning.” He’s
watching the acceleration. John Hodge was flight director. I just
took my headset off, I laid it on the console, and laid my head down
there. I thought, oh, god. Even today if we get together, some of
them will start reminding me, “Oh, Commander Carlton, you know,
we got to teach him how to command.”
A few weeks later, Kranz came over and handed me a little ballpoint
pencil, pen. He said, “Bob, you can have this.”
I said, “What do you mean? It’s no good.”
He said, “This is a memento from me to you.” He said,
“I was going to start my stopwatch, and I had it in my left
hand. I was writing with my right hand and instead of pushing a button,
I just shoved that pencil in and just splintered the end of it.”
Anyway, those little things.
Now let me come back to our—we were ready for Apollo. Those
were some human things. That’s the frailness of the human being,
and humans make mistakes. In Apollo we tried to have a flight control
team and everything set up so as to be able to minimize the human
mistakes. I think I mentioned to you before when we were talking about
Gemini, we have a dichotomy when you talk about man in the loop. On
one hand, man is prone to error. I think I mentioned to you that if
you look at aircraft accidents, 90-plus percent of them are caused
by human error.
So, on one hand, you want man in the loop because he has the flexibility
to work around problems that occur. On the other hand, when you give
him the total operation, he’s prone to make mistakes. I’m
a firm proponent of man in the loop. I think that we probably wouldn’t
have done 10 percent of what we did if we’d had it all automated.
I doubt that we would have had a single successful mission of landing
on the Moon.
If you look at some of the problems we worked around and corrected,
almost every mission had some unforeseen problem that would have put
us dead in the water. But once you recognized it and had men in the
loop, we got turnaround, and we could get it to work again. We’d
figure out a way to work around it.
But the stuff that was automated, it don’t make mistakes, provided
that it don’t run into a failure or unforeseen situation. So
how you do that, well, that caused us a lot—we had a lot of
learning to do there in how to do that. We went through a tremendous
amount of procedural things that we did to try to circumvent this
idea of man making mistakes.
One thing we did was we always had two people looking at a function.
We probably had three because Kranz was a fantastic systems flight
controller himself. He understood systems. He looked over our shoulder
a lot and would ask questions, how’s this and that and the other.
A lot of times that was very beneficial and helpful, made us look
at it from a different setup, different perspective.
But we always tried to plan things so that we had two different people
correcting each other. In SSR, we had a guy that was looking at propulsion
systems. That was his responsibility and he made the calls. He looked
at the systems and he diagnosed and recognized when problems were
happening. He should have seen them first always. But the guy on the
MOCR [Mission Operations Control Room], we insisted that he know the
systems to the level to be able to troubleshoot it and operate it
by himself without an SSR. So he was a double check on the guy on
the SSR doing their job right.
Likewise, the guy in the front room, if he made errors, the guy in
the back is the double check. So they worked together. There’s
the checks and the balances there to keep either one of them from
making a mistake, and that saved our bacon. There’s a lot of
times that that would come to the forefront and you got to where,
time allowed, you tried to confirm with each other, but you also got,
if you listened to the tapes, you’ll think that was not happening.
But when you work with somebody for a long period of time, you almost
know what each other’s thinking.
A lot of the procedures, the guy in the back room reports something
and the guy in the front room won’t even acknowledge it. He’ll
just report it to whoever it needs to be forwarded to. So it wasn’t
that he failed to coordinate with the guy in the back room. He knew
the guy in the back room was expecting him to go that next step, and
he would hear him make a response. So there was a coordination between
them going on there, but it might not be apparent to you if you weren’t
intimately familiar with what they were doing.
You’ll see that come to the forefront in one of these tapes,
and it will almost be invisible to you. We had [an indication that]
a thruster failed on. If you’re listening to that, there’s
some other voices going on at the time, you probably won’t hear
my voice, but Bill [William E.] Sturm, that was in his area. He should
have recognized it first and called it to my attention. But somebody
had shoved a book up over his event light, and he hadn’t noticed
it. When it came on, it had an event light that come on that showed
you the thruster was on, an indication of a failed thruster. All you’ll
hear on the loop, and it’s so short and terse that you won’t
even notice it. In fact, as I listened for it, if I didn’t know
where it was, I couldn’t have told it. I said, “Bill,
ignore the event light. It’s telemetry. The RCS failed event
light is telemetry.”
Bill said, “Roger.” And that’s the only thing he
said. There was a human error corrected by having two sets of eyeballs.
There was also the working relationship so close that you didn’t
need any further discussion. The teams worked that way, and that saved
us from making mistakes. You really had a third set of eyeballs looking
at things: the flight crew. We didn’t make the switch position
changes and so forth. The flight crew flew the LM. We diagnosed the
problem, and if it had to have corrective action, we would relay that
to Flight and say, “Tell the crew do this.” The Capcom
is listening and I’d said okay, the Capcom would voice it up
and the crew would do the action. If they didn’t like it, they’d
question it. “Why’re you doing that?” So you really
had three sets.
If I add Kranz to it, I had four. Not all flight directors could be
counted on to be the fourth set. It had varying proficiencies among
flight directors. Some of them were very concentrated in their knowledge
of trajectory kind of things and had not had the long systems expertise
in exposure and others. Wherever their strengths were is how much
some of them would reinforce different groups of guys. Kranz happened
to reinforce, he was a systems-oriented guy, so he reinforced us.
We had four sets of systems.
Well, as we went ahead, then, getting ready for Apollo, the new guys
also learned this, just as we did, this system and what we’re
doing in this game of flight control and by the exercising of mission
rules and the onboard procedures and the malfunction procedures and
the preparation of the drawings that we used. Those were instruments—and
I can’t recall if we discussed this in the Gemini conversation
or not—those were all instruments that I think were just critical
to making the program run as smoothly as it did. They were a means
and a mechanism for the program management people to have their desires
carried down to the very lowest echelon.
For example, the program management might say once we’ve landed
on the Moon, the primary objective is to gather some rocks. Well,
we also had cameras to take pictures, and we had all kind of instruments
they took out and planted on the Moon. But they set the priorities
for everything we did. The first priority is to land on the Moon.
The second priority is to do this and that and another and another.
But once we knew what was important to them, we planned our reaction
to any unforeseen problems in such a way that we maximized the return
according to the priorities they had assigned stuff. We wrote that
down in mission rules and reviewed it with them. We’d tell the
manager, “Now, if we have this failure, this knocks out this
system. It don’t work anymore and we can’t do this. But
we have a limited ability to do this and this, and we’re going
to do them in this order.” He would look at that and see what
we’re trying to get done. “Here’s the priorities
you gave us.”
If he disagreed with us, you’d say, “No, I’d rather
do this.” So it’d give him opportunity to see how we were
following through on his overall programmatic priorities. There were
times when we didn’t give him a vote. If crew safety was concerned,
it didn’t matter what he wanted, we were going to bring the
crew back. But that’s where we overrule with the flight control
priority. But he knew that. We reviewed that with him, too, so it
was a means of communicating from the top to the bottom.
I think another thing that made the program a great success was there
was a philosophy, a programmatic philosophy, that was, I think, unique
in NASA. I had never run across it before anywhere in my experience
in the military or in industry. That philosophy was that there was
always an open ear at all levels of management to a concern of any
person in the chain of the team. It didn’t matter how low he
was. When we had reviews of spacecraft, they would encourage—it
didn’t matter where you worked, who you was or what his level
was or what his boss thought, he could write up what we call a RID
[Review Item Disposition] discrepancy report on “I think this
is wrong with the system, the design is flawed,” or whatever.
That got bumped up the chain, and top management would finally look
at it, and they would make a ruling. Whoever that impacted had opportunity
to argue the case. “Well, he’s off base.” But the
fact that the little guy, no matter where he was, he was a part of
the team and his voice got heard, I think that was the very heart
and soul and strength of why the program was so successful. That weeded
out a lot of problems that could have come to the forefront and bit
you later on. It was a very conscious thing, part of the NASA management
philosophy to do that. That impressed me at the time, and I think
it was unique to NASA.
I doubt that it happens even today. Usually, the boss don’t
want the problems that’s under his command to be aired to the
upper echelon. You don’t go around the boss. So the effect of
that is to mute any dissent about what’s going on, and upper
management only then sees what the next level below wants them to
see. Therefore, they don’t always have full visibility. NASA
didn’t work that way. Considering as much as was at stake, it
probably was a very good thing that they didn’t. It caused probably
a lot of extra wheel-spinning. They worked problems that the majority
of the problems this little guy thought was insurmountable or big,
the upper chain knew about it already and had made a decision we were
going to live with it for one way or to work around. So that was sort
of a uniqueness of the program.
I think there was another thing that was unique to the program and
made it a success, was the way in which the NASA management worked
with this gigantic team. It’s hard even today talking about
it, to comprehend how many people were involved in that Apollo Program.
You had several spacecraft with the manufacturers scattered all over
the United States. If you went to KSC [Kennedy Space Center, Florida],
they were simultaneously building the KSC facilities with a complex
of contractors went every which way.
The NASA program management, trying to get all of these diverse people
to work together so when the hardware got together it worked together.
You had a booster sitting on a booster sitting on a booster sitting
on a booster, each one of them built by a separate contractor, and
yet they had to talk to each other through their interface. As it
went into orbit, the mechanical strength of the interface had to work.
It interfaced to the Cape. As it was sitting on the pad, it interfaced
to the Cape. When it got into orbit, it interfaced to the control
center via the telemetry link. It’s mind-boggling to see how
many different things had to work together.
Then all of those contractors. Kind of like one of those astronauts
said one time, “I’m up here in orbit.” He said,
“You guys said there’s 20 million pieces here and every
one of them built by the lowest bidder. That don’t give me much
of a warm feeling.” But they worked together. The fact that
NASA could manage that horrendous a group of people with their own
interests, and somewhere I think another thing took place. I think
the people, all of the people that worked on the program, they had
a sense of pride in what they were doing and a sense of “We
want to make this work,” just like that flight control team
did. And I believe that transcended what we normally see in contractors
with a profit motive overrides everything else. I don’t believe
that happened in Apollo.
I believe that was one instance in our nation when the whole complex
of industry and government were working together toward a common national
goal in the sense that we’re going to accomplish this goal.
Through the whole team there was a sense of pride in what we’re
doing, had nothing to do with the money they made. In fact, I doubt
that the management of those contractors, I doubt they cared about
the money at that time. We hope we make a profit, but I’ll bet
if you could look in their brains and see what was really motivating
them, you’d have seen that same sense of pride that you see
emanating from myself over what we’ve accomplished, and everyone.
When we get together, it never ceases to amaze me, when we get together
in some of the old reunions, there’d be contractor people come
in a lot of times. Or if you run across one on the street somewhere,
it don’t matter where they worked, there’s that sense
of “Boy, we did that, yes.” Everyone of them, it don’t
matter what he did, probably even if he swept the floor in the plant
up at McDonnell Douglas, there’s a sense of “I did my
part in that.”
I look at the flight control team, and I was talking about the sense
of camaraderie amongst them, I believe in the sense that sense of
camaraderie really is bigger than that. It encompasses everybody that
ever worked on it. I can’t tell you why it’s that way,
but I know it is.
Or if I looked broader than that, you could probably be a better judge
of this than me, but if I look at our whole nation, when I see like
one of the anniversary years come up and I see people talking about
it, and I’ve gone out to colleges and talked to the kids and
gone different places, as I hear them talking about it, I perceive
that there’s a national sense of pride in that more than any
other thing this nation ever did.
I bet if you went out and you talked to the people who are thinking
about what are we doing as a nation and you ask them, “If you
look back at our nation’s history, what is it you think are
the tall poles extending high in your memory over our accomplishments?
What is it you take the most pride in what we did as a nation?”
I’ll bet you Apollo landing on the Moon would be probably the
top. If not, it would be right up there amongst them. We’ve
done a lot of good things in this nation, a lot of things, things
we’re proud of, great accomplishments. Probably, notice I said
“probably,” some greater than that. Probably some greater
than that, but we take a lot of pride in it. So that sense of camaraderie
is not just unique to my flight control buddies, it’s a national
sort of a thing.
[Well] as we went on, the thing I think that, as I started out about
thirty minutes ago in this rambling conversation, that made it a success
and I think was unique to it was the teleconferencing. The program
managers would have a teleconference. I’m not sure about this,
but I believe NASA probably pioneered that concept. I had never heard
of it before. We would sit down in a big room, and there’d be
a table there and there’d be a screen at the end of the room.
The program manager would be at the end of the table, and everybody
that was going to have a vote in this process of today’s business
would be around the table. Then there would be another table at Marshall
[Space Flight Center, Huntsville, Alabama], there’d be another
table at KSC, and another table at Headquarters. Everybody, we’d
call that a teleconference.
Today’s agenda, whatever decisions were being made, they’d
list that up, and the other centers would have sent their charts in.
So if we were debating a change to a booster of some kind, Marshall’s
booster charts would be up there, and the guy on it, you’d hear
him talking. He’d start talking about this chart, and the guy
in the back would throw his viewgraph up there. Then you’d have
someone of our propulsion people that had been talking and intimate
with what was going to be said by Marshall would point out on our
screen so you could follow easily what was being discussed and debated.
When you got through, the program manager would set there, and we’d
all looked at this story unfold on the screen. We heard the guy down
there that proposed it.
The program manager would ask everybody else, “What does this
do to you, Cape? Does that obsolete some of your equipment? Do you
agree? What’s your thoughts about this? What’s this do
to you, Contractor?” Everybody that was impacted had his chance
to put in his two bits and then the decision was made on the spot,
Bob [Robert F.] Thompson, I believe he was the program manager, or
the program managers with Bob Thompson would say, “Well, guys,
look, we’ve got to move on. We’re willing to baseline
it today if you had it.” You knew when he started out like that,
he still had some people that wasn’t happy with it. There wasn’t
a decision available to him that made everybody happy. He was taking
the middle of the road. He had to keep the ship moving. He would say,
“Guys, we’re going to baseline this today, but we’ll
come back and revisit it if we run into problems we can’t surmount.”
So everybody, “Okay, boss.” So the team marched on.
I think that teleconferencing was a tool that was just invaluable
to NASA in planning and putting the program together. We did it just
extensively. Not just Thompson, but we had teleconferences all the
time. Maybe that was a new era that just arrived in the nick of time
that enabled the program to work so smooth as it did with so many
people all over the United States.
Well, that brings us up to where we’re beginning now. I think
I’ve covered and sort of ticked off some of the points here
of interest. I don’t know where your interest, and other people
who try to record this as how it all happened, will be strongest,
but that’s sort of the programmatic aspects of coming up to
So then if we move our attention on in closer to the mission being
accomplished, the team gradually got all of their paperwork and their
procedures and their plans together and began to get them trained.
Maybe there’s one thing that ought to be mentioned in the preparation
for the mission, is training this new group of guys. By the time Apollo
got here, our troops had—somewhere in Kranz’s outfit,
I don’t know who it was, [Gordon M.] Ferguson was part of them.
There’s a whole bunch of them. There’s one group of guys
whose job was training. They were the ones that laid out the simulator
and guided the simulator being put together. They also laid out a
schedule of special training sessions, where we had people who specialized
in training come in and teach us the systems. That was good, but it
didn’t carry a flight controller’s knowledge down to the
level it had to be. A flight controller’s training had to be
a lot stronger than, I guess, anything else I’ve ever seen.
My background is aircraft, and I saw military training. I’ve
seen training of a lot of varieties, but I don’t think anything
ever approaches what we demanded of a flight controller. Generally
speaking, you tell an operator, “If you want to drive a car,
here’s the way you shift the gears and here’s the way
you run the motor and here’s how everything worked.” Or
if you want to teach a pilot to fly a plane. “This is how everything
works, and if it don’t work right, well, I don’t expect
you to worry about that. Land it, and we can get it fixed.”
With a flight controller, that’s not sufficient. When you put
a crew in orbit and they’re halfway to the Moon and something
quits working, you don’t just bring it home and fix it. You
have got to live with what it is and you’ve got to figure out
some way to make it limp along and come back home safely. The flight
controller is the troubleshooter of the systems.
To troubleshoot the systems, he’s got to know how it works down
to the intimate detail. But not just how it works. He don’t
really come into play until it quits working. Now it don’t work,
and how do you make do with what you’ve got?
For example, to illustrate that, I’ll give you two illustrations.
Let’s say that here is a solenoid valve that opens the valve
and lets fluid flow through to an RCS thruster. Let’s say that
I had a failure in the electrical system and my battery voltage is
going down. Now, this solenoid was designed to work at 24 volts, plus
or minus a volt. The contractor designs it to that. The specs [specifications]
says it’s got to meet that before you launch. If it don’t
meet it, they’ll change it out. Now I’m in orbit, and
the electrical system has a malfunction and my power starts going
down. I can see the power going down, and I can project ahead, this
battery is dying, but it’s going to live twelve hours before
its voltage goes to zero.
Well, at five hours its voltage is eight volts prior to the end. And
at ten hours, its voltage is sixteen volts, and so forth. Where is
this solenoid going to quit working? That becomes the question. I
would like it—I’m going to be ten hours before I am close
enough to home to do a retrofire and come in. So is it going to be
alive, and will I have enough voltage at ten hours? Somebody’s
life is hanging on how well I know that. Well, I don’t have
that information, folks. They don’t test you to that. The contractor
said, “You asked me to build it to work plus or minus one volt
around 24 volts. Don’t ask me. I don’t know that.”
And we went over it. We could not. It was very difficult. I won’t
say we could not. It was very difficult to make program management
understand we need to know the outer limits of where everything works.
And it’s very difficult to get these young flight controllers
and the contractor flight controllers and contract engineering people
to appreciate why you wanted to know the outer limits of where everything
worked. If you call the engineering people at the contractor and said,
“Where’s this thing work? Where’s the outer limits?”
he says, “Man, I don’t know. We never tested that. It’s
going to fail somewhere.”
So we pored over the test results of where they had failures and had
abnormal tests, and that’s what I expected the flight controller
to know. Now, he couldn’t get the information, was the problem.
So we went around and around and around with the program office. That
cost money to do off-nominal testing. So we got it. Sometimes they’d
test stuff and sometimes they wouldn’t and sometimes they’d
have a failure.
They were running a thermal vac [vacuum] test over in the NASA center.
They had a piece of hardware sitting there in a big vacuum tank. Somebody
flubbed up and they turned off the cooling system to it. So this thing
is sitting there working in a vacuum with no coolant. Well, we got
to find out where it quit. We could never in the world get the program
manager to have jeopardized an expensive piece of equipment like that.
That was pure gold information to us. As I had the flight controllers,
trying to teach them the systems, I made them go hunt. We scoured
every test report that went on. In doing that, they’d come back
and say, “This thing failed.”
Now I’m circling the wagons here. The subject I’m on is
how do you train a flight controller. The knowledge is not always
there to train him, but you get it in bits and pieces. Now I’ve
got the guy, beginning to get him conditioned to what he needs to
know. Then it comes a failure on this test over at Timbuktu on thrusters,
and I call that prop [propellant] guy in. I say, “Well, Bob,
how come that failed? I want you to go get all the results on that
and you come back and explain to me why that failed. Should it have
failed there or at a higher level or a lower level?” So he’s
digging into that system component by component by component as opportunity
presents itself. So that was one mechanism to train him in what he
needed to know.
Another mechanism to train him was we had our own flight controllers
prepare what we call malfunction reports. What we did was we took
every single telemetry parameter on the bird and took the prop guys.
I said, “Prop guys, I want you to tell me what you would do
with every single parameter on there if it went out of limits. Let’s
postulate how it might go out of limits. It might go high. It might
go low. It might do this. Postulate everything it could do and then
you tell me, what would that indicate to you. That one parameter now,
what would that be a symptom to you of what kind of failure is impending
So he went in and he took every single—like he might take a
tank pressure. Here’s a fuel tank. That fuel tank is full of
fuel. The way you get the fuel out of it is you put pressure in the
top of it. Pressurization. You put enough pressure in there and that
will squirt the fuel out the bottom. We didn’t have a pump that
pumped it. You used fuel pressure or blanket pressure. Where did that
pressure come from? It came out of a tank of gas. In the LM it was
the tank of liquid or mix, a slurry mixture of ice, liquid gas, nitrogen,
and then gas, all. It would come out and it would run through a heat
exchanger. The fuel running out of it into the engine would run through
this heat exchanger and transfer heat and change the liquid gas to
a gaseous gas. Then you’d come around the top to a pressure
regulator and come in the top of the tank and apply that pressure.
But if you had a temperature sensor on the top of the tank, just to
give you an illustration of looking at a parameter, and you saw this
temperature now, and you’re rocking along, and it’s supposed
to be in a certain band, you’re rocking along, and all of a
sudden you saw it go to—maybe it’s supposed to be at eighty
degrees, and all of a sudden you looked and it did a step function
up here of 300 degrees. What would you do?
Well, the prop guy’d study on that a while, and he’d look
at his information. If that tank gets hot, it loses its strength,
and it’s liable to blow up. The contractors told us, “If
you’ve got a combination of the pressure of this much and a
temperature of this much, fracture mechanics sets in and the tank
is in danger of rupturing.”
I say, “Well, should we abort the mission then and get off of
it?” No, ain’t nothing wrong. If I look at a tank and
the temperature of that tank, it’s got a thickness of the metal.
Tanks, big pieces of metal, don’t change temperature like that.
You can put a lot of heat in it, and what’s going to happen
is that temperature is going to start doing this, won’t it?
So I know by the action of the parameter when I’ve got a temperature
problem versus I’ve got an instrumentation failure. So we went
through every one of the parameters like that, and he wrote a malfunction
Then after he got through with it, the next team of guys I wanted
to train, I told them. This might be [Robert S.] Nance [Jr.] first
cut around. Then come along the next guy, Bud [Bernard A.] Durand,
and he’s going to train. I say, “Bud, here’s the
malprocedures. I want you to go through them and rewrite them.”
Well, Bud starts through it, he does this same process, and if he
wants to change that, Nance is going to come up in arms. You’ve
just attacked his integrity of his work. So I had a check and balance
here going on. But it forced Bud Durand to learn it just as good as
Bob Nance. So it was a training tool.
Also, it developed a mindset that you might encounter a new problem
that you hadn’t even thought about, but you’ve done this
procedure so many times that you developed, I don’t know what’s
the right word, a technique, a philosophy. So when something new was
encountered, you kind of knew how to go about it. You were always
limited by how well you knew your system.
The flight controller had to know the system. You can see from what
I’ve been trying to illustrate. He had to know things much more
to a lower level than a normal operator has to know things to diagnose
and troubleshoot a system. He had to know how to make the system work
while it was crippled, not while it’s just operating normally,
while it was crippled. But, otherwise, we didn’t hardly need
him. That’s where you needed him the worst.
Well, if we move on to—now, see, we’re running out of
time. Let me pause a moment here and ask you, first chart will help.
The reason I’m going through this, and I’ve gone through
this with you on the board, but whoever might be looking at this later,
it might not mean much to them. This might help them understand what’s
Inside the MOCR there—is your video seeing this? Inside the
MOCR this illustrates kind of the team of guys. This box is the flight
director. As we go through the tape, the first time we hear a roll
call, that’s the flight director. He’s the boss of the
whole team. I’ve only drawn part of the team here. The first
row of consoles under him are people responsible to him. The two guys
in the LM called CONTROL [Control Systems Engineer] and TELCOM [Telemetry
and Communications Engineer] and later the name is TELMU [Telemetry,
Electrical, and EVA Systems Engineer] or it might be TELMU here. I
don’t remember. Somewhere we changed his name once. Then we
had CSM guys and Capcom and FIDO and GUIDO [Guidance Officer]. I don’t
show their boxes. So as you hear a status check, the flight director’s
asking each position all the way through the room, “Are you
ready? Are you go for power descent?” And each one of them’s
responding to him.
You’ll hear one, that’s the GUIDO, that was Steve [Stephen
G.] Bales. He was a real young guy, and he really was excited that
day. He was spring-loaded. He screamed to go. [Laughter] We all kind
of had humor. It kind of broke the tension at the moment when Steve
was so excited. I could hear Kranz kind of chuckle a little bit as
he went on around. But, anyway, that’s what he’s doing.
He’s taking a status check.
Everybody’s looked at the systems and this is really, “Is
there anything in your system? We’re fixing to land on the Moon,
guys. So you tell me if your system’s go.” That one, the
reason I picked that was two things. One it gave you, you could hear
Steve’s voice. And it gave you a sense of the humanness in this
team and how uptight everybody really was. The other thing was, it
gives you also a feeling of how smoothly the team works together and
how Kranz, the flight director—and this would apply to every
one of them—the flight director is the boss. He’s in control.
This status check lets you see that team working as a unit and the
boss leading the team. Like the orchestra, he may not can play every
instrument, but the director, he can hear when that music is not right.
Once, I asked Kranz, I said, “Kranz, why do you make this big
deal about a status check? Why don’t you let us just punch the
button?” I had on my console a green light and an amber light
and a red light. Green says I’m go. Amber says I got a problem
I’ve got to work on. Red says abort. I said, “Use the
lights. That’s what you want to know, isn’t it?”
He scratched his head and he said, “Well, Bob,” he says,
“I like to hear the quiver in your voice.” He said, “I
can calibrate how bad things are when I listen to your voice.”
I think it was [Christopher C.] Kraft [Jr.] once, and they was interviewing
Kraft, and they said, “You don’t know all these different
positions.” They said, “How do you boss all these people?”
He said, “I’m like an orchestra conductor.” He’s
the one that used this analogy. He said, “I may not could play
the fiddle, but I can tell by listening if it’s in tune.”
Anyway, with that, let’s listen to the status check. You keep
in mind, as you listen to this now, there’re three loops you’re
going to hear. One, you’re going to hear the flight director
as he talks to the people. In the status check, that’s the only
one you’ll hear. Later on, you’ll hear the air to ground.
Anytime you hear, Charlie, the Capcom talking, Charlie [Charles M.]
Duke, he’s talking via air to ground, generally speaking. You
can tell when he’s talking to the ground, or he might be talking
on the internal loop. But that’s the second loop that’s
on this tape. Then the third loop is the systems loop between myself,
CONTROL position, and the back room with the three guys, Props, PGNS
[Primary Guidance and Navigation System, pronounced “pings”],
and AGS [Abort Guidance System], and you’ll hear those guys
interrelating later on, but not in this status check.
Each of the other console positions in the MOCR also has a team of
people in the SSR that’s supporting, and that’s illustrated
here. So the voices you’re going to hear, you may hear some
of the guys in the back room communicating to me, but most powerfully
and probably the only thing you’re going to hear is the flight
director taking a poll around the room in the MOCR. So with that introduction,
why don’t we turn it on and see what it sounds like. You’re
going to play it for just a short distance and then skip to the next.
And to provide further clarification, these are tapes you made off
of your console.
And this was Apollo 11 getting ready for the lunar landing.
We’ll go ahead and play the first segment.
We’d just come out from around the Moon, looked at our vehicle
systems. Kranz gives us a chance to—.
note: The following segment was recorded on 20 July 1969 in the Manned
Spacecraft Center Mission Operations Control Room. It includes intercom
loops between the LM Control Console, its support rooms, and the Flight
Director, as well as communications between the Apollo 11 spacecraft
and Mission Control. Conversations over these loops frequently occurred
simultaneously. Mr. Carlton’s verbal comments made over the
tape during this oral history session are included in parentheses.]
Ok, all flight controllers, Go/No-Go for powered descent. RETRO.
F. Dieterich: Go.
H. Greene: Go.
G. Bales: Go.
R. Puddy: Go.
GNC [Guidance, Navigation, and Control Officer].
N. "Buck" Willoughby: Go.
EECOM [Electrical, Environmental, Communications Officer].
W. Aaron: Go.
F. Zieglschmid: Go.
Capcom, we're go for powered descent.
taped intercom loop segment]
All right. Now you heard him take the poll around the room, and when
it got through, then he made the decision to tell them. He said, “Capcom,
we’re go for powered descent.” If we followed along, we’d
heard Capcom tell the crew, “We’re go for power descent.”
So that was a go/no-go point in the mission. As the Capcom relayed
that up to the crew, then they were ready to proceed to the next stage.
As we went down the mission profile, you’ll hear those go-no
goes at several places. In the actual middle of the burn, going down
to the lunar surface, we went through phases. We took a go/no-go status
check to go to the next phase. For example, as you were going down
in the early part of the flight, if you had a problem that you saw
would jeopardize your ability to land and you knew you weren’t
going to land, you’re going to abort, well, you’d rather
abort while you’ve got the whole descent stage there and use
the descent engine to abort back. So as long as you have the descent
engine with enough delta-V [change in velocity] in it to get you all
the way back home, you’re going to abort right now. You’re
not going to wait a little ways. Later on, you’ll reach a point
where the descent engine don’t have enough delta-V to get you
back to orbit, and you’re going to have to stage. It might get
you half way and then you stage and go the rest of the way with the
ascent engines. So that is a discrete point. Before you cross that
point, you want to be dad-gum sure everything’s go. So that
would be a status check. A little later you get on down and so on
and so forth, you’ve got checkpoints.
Now if you can go forward to where we pick up the burn, I forget what
checkpoint I call that.
Where they’re doing the checking that they had at least 10-percent
thrust and they’re starting the engine.
When you start the engine, there’s a short period of time when
you burn at very low thrust and it settles under. That creates artificial
gravity in the tanks. The fluid settles down against the bottom of
the tank. That’s an ullage. We call that an ullage maneuver.
Then after you had that settling effect, then you power the engine
up and you begin to burn in earnest. So you may hear the ullage call
take place. Okay, go ahead.
taped intercom loop segment 2]
I got ignition.
That's Charlie Duke. He's nervous.)
Let us have it if you don't see it.
He's on my loop.)
Do you see anything there, Bob?
DPS [Descent Propulsion System, pronounced “dips”] arm.
Rog, DPS arm.
I heard ullage call.)
E. "Buzz" Aldrin: [Z]ero. Ignition 10 percent.
10-percent TCP [Thrust Chamber Pressure].
That's Bob Nance.)
Rog, 10 percent.
voice]: Looks good.
taped intercom loop segment 2]
Hold a minute there, and let’s talk about that. What you heard
there was a variety. That was Charlie Duke. He’s watching the
systems, nervous as a cat. He’s on system loop. There’s
three loops you’re listening to. The systems loop, if anybody
comes and talks to me on the systems loops, they’re supposed
to be on the systems loop, and that’s what Charlie was doing.
He’s coming up there, saying, “Bob, let me know. What’s
going on? Is it happening? Is it happening?”
Then you heard Bob Nance’s voice in the background saying this
and that. I forget what he said. You also heard Bill Sturm saying
we had something happened. So they were reporting to me, and I was
reporting what I needed to report. Certain things were important to
know. Ullage taking place was important to know. Bob Nance reported,
“I see ullage.” I passed that on to the flight director.
That was the report that he wanted to hear. So that’s what you
You heard the flight director and you heard—did we hear the
flight director? I think we did. You heard the Capcom, Charlie Duke,
talking on the Systems 2 loop. Then you heard the SSR guys reporting
what’s happening on the Systems 2 loop.
Okay. Go ahead.
The next one you had marked was the go/no-go point for landing.
Okay. I don’t remember where that was in the trajectory. Play
it and maybe I’ll be able to recall where it was at.
taped intercom loop segment 3]
TIGO is go.
We have position 2 on LR [Landing Radar].
Rog. Position 2. All flight controllers, 20 seconds to go/no-go for
Eagle, you're looking great. Coming up 9 minutes.
We've been burning nine minutes.)
Margin is looking good. We're coming up on our nominal here.
Okay, all flight controllers. Going to go for landing. RETRO.
Manual attitude control is good.
Capcom, we're go for landing.
Eagle, Houston. You're go for landing. Over.
Nine minutes. Margin is about four and a half.
taped intercom loop segment 3]
All right, stop there.
We were nine minutes into the burn. We’d reached one of these
go/no-go points. Kranz was going around the room before he went through
that gate. You heard Bob Nance. In the go/no-go, you heard Kranz,
the flight director, going through one position at a time all the
way around the room. Each guy had to give a status that he’s
ready to go to the next phase.
You heard Bob Nance. He was the staff support room guy that was over
propulsion, responsible for the propulsion systems. He was saying,
“Our margin is okay.” What he was talking about there,
the descent propulsion system had big fuel tanks, and ox [oxidizer]
tanks. If we projected the whole burn, I forget the exact number of
minutes, we had around twelve minutes’ worth of burn, ability
to burn that long, supposedly we’d land on the Moon.
Before we ever made the mission, we did simulation after simulation
and analysis after analysis, and they sized those tanks to have a
margin left. When you landed, you had to have a good bit of gas left
in the tanks. You didn’t want to run out of gas, in other words,
before you landed. Before we run this mission, all of those analyses
and simulations said that we’ll have a goodly margin of gas
left in the bottom of the tank.
We had, in the very bottom of the tank—and I’ve got a
chart there that shows you this. In the bottom of the tank, we had
a sensor. We had two ways of telling the fuel in the tank. One was
we had a level, just like a gas gauge in the car. The other is we
had a low-level sensor. The Volkswagens used to have a little emergency
tank in the bottom. You had I don’t know how much left. In the
LM we had this little low-level sensor, so this represents two fuel
tanks. This low-level sensor is right down at the bottom, and if you
uncovered it, you had X seconds left. I forget exactly how many. Around
120, I believe, of seconds of fuel left if you continued to burn at
a 1-lunar G, in other words, a hovering kind of a thrust level. You
had that much time left when you uncovered this low-level sensor.
The reason you needed that was twofold. The granularity on this main
probe here measured the quantity in there, and that indicated to a
gauge onboard this. The fuel gauge is onboard. This probe, we also
came down to the ground with telemetry to read that probe. But it
went in increments, like 1 percent increments. So you’d go along,
and when you’d burn enough fuel to step down one, you’d
step down one. In other words, the coarseness of this, the precision
of his reading was not sufficient to get you down in the seconds.
So when you tripped this little low-level, you knew how much you had
left, and then you counted it down.
Well, when Bob Nance was reporting margin, he had been looking at
these trips, and then he had been extrapolating the points to give
a smooth curve. Here’s the usage rate, and each engine is a
little more or less efficient than another one. They’re not
all identical. So he was measuring the delta-V we got out of this
quantity of fuel to see how efficient the engine was, and then he
was projecting that down to what margin we’d have left when
we landed, how much margin would we have, how much fuel would we have
left when we landed. Bob’s reporting that margin way back up
at nine minutes. He’s already projected it down to see if we’re
going to have enough fuel.
Well, now as I was listening to the FIDO, he had previously been saying,
“We’re long. This trajectory is going to be long.”
I never really did understand why it was we were long, but for some
reason, and we were going to be burning longer than we thought. So
we were nervous about that, and I’m bugging Bob and we both
are nervous about it. He’s reporting, “The margin’s
okay, the margin’s okay.” Well, now, as we got down close
to the surface, we were not supposed to ever trip that low-level.
We’re supposed to have a big margin in there.
But unbeknownst to us at that time, when you got down to the surface,
there was a big crater. Armstrong took over manually and flew it over
this crater and landed on the side of the crater, the edge of the
rim over there. But prior to that, we’re not going to land where
we’re supposed to, so what looked like good margins turned out
to be we tripped low level. We’d been assured that would never
happen. We didn’t expect that to happen. Not only did we trip
low level, it counted on down to sixty seconds left. Not only did
we count sixty seconds, it counted on down to thirty seconds left.
After thirty seconds, when we shut down, I had a stopwatch that started
when that low-level tripped.
So I clicked my stopwatch and started it. As the hand went around,
I’d put a little piece of Scotch tape. Very scientific thing
here. A little piece of Scotch tape and a mark on it that said when
you hit this one, there’s sixty seconds left. When it comes
on down to this one, there’s thirty seconds left. Then when
it comes down to the point we need to abort, we don’t want to
be empty at that time. There’s some uncertainty in this measurement
process we’re doing, so we need to put a margin in there to
be sure that we don’t run into that uncertainty. So we put a
little extra in there to count for that.
Then we said, okay, when the astronaut hears this thing abort, we
want to give him every chance to land, so we want it to be as near
empty as it can possibly get, but on the other hand, we don’t
want him to run out of gas ten feet off the surface. That’s
a bad thing to do, you know. So you had to hit both. You wanted to
make the mission, but you didn’t want to jeopardize your crew,
and you wanted to play it just as tight as you could safely.
So you put these margins in for uncertainty of your ability to measure
the quantity, for the uncertainty in what the thrust of the engine
might be doing. When we see that he’s out and he’s got
to make an abort decision, we want him to hear the “abort”
word to punch the button right now. Well, there’s a time delay
of almost two seconds from us sending [the message] up to the spacecraft.
The engine’s burning during that two seconds. So we had to put
in a margin for that.
Then when Nance reports it to me, and my brain takes a little while
to processing it, give me a half a second worth of burn for that.
When I report it to flight, I’m going to give him a half a second
to process it. I’m going to give Charlie Duke a half a second
to process it. We had all these out. We had a little tat of margin
that when we said “thirty seconds,” it was really thirty
more seconds of burn plus this little bit of margin. When we said
“abort,” that astronaut had to be programmed. He didn’t
think anymore. When he heard “abort,” he better hit the
button or he is not going to make it. There’s just enough gas
left in there. When he hears “abort,” we had some margin
in there to, if he had a downward velocity, there’s enough gas
in there to turn him around and start him upwards, because there’s
a little time delay. When he hits abort and stages off that descent
engine, the ascent engine starts burning and firing in the hole and
comes off of it. But there’s some milliseconds of delay while
he’s building up velocity. You don’t want to be falling
in that. You’ve got a downward velocity, so you’ve got
to stop that downward velocity. You assume you might have one. Then
you can get it started back up.
So, anyway, when Nance said, “We got good margins,” he
is anticipating that we’re going to have goodly amount of fuel
left there. He’s not realizing that we are burning long and
that later on we’re going to fly over a crater, later on as
we got down there and we begin—and it did, we tripped low level.
When I punched the thing there, I didn’t think there was a chance
in the world of us landing. I was looking at the altimeter and we
had a heck of a way to go. I didn’t know we were over a crater
and I was reading to the bottom of the crater. But when you come over
the top of the crater, that distance to go went “ch,”
like that, we’re there. But I didn’t know that.
Well, anyway, that’s what was happening. Nance was reporting
on the margins. You heard some of the other guys making reports to
me and so forth. All right. Now go ahead and pick up and let’s
taped intercom loop segment 4]
Low level’s tripped.)
Light's on. 6[0 feet], down 2 1/2.  forward.  forward.
And we're puckered.)
Using a lot of RCS.
40 feet, down 2 1/2. Picking up some dust. 30 feet, 2 1/2 down. [unclear]
Stand by for thirty.
4 forward. 4 forward. Drifting to the right a little.
20 feet, down a half.
Drifting forward just a little bit; that's good.
And we're puckered right there. You notice how quiet it is in that
Contact. This'll be Charlie Duke.)
Okay. Engine Stop. ACA [Attitude Control Assembly] out of Detent.
Out of Detent. Auto.
voice]: Shut down.
Mode Control, both Auto. Descent Engine Command Override, Off. Engine
413 is in.
We've had shutdown. [Cheers in background]
We copy you down, Eagle.
APS and RCS [unclear]
Ok, everybody [unclear].
Roger. Ok, fellas. Steady now. Stay with it. Keep your eye on it.
Houston, Tranquility Base here. The Eagle has landed.
My guys. I try and slow them down.)
Don’t relax yet.
Roger, Tranquility. We copy you on the ground. You got a bunch of
guys about to turn blue. We're breathing again. Thanks a lot.
Okay, keep your eye on it.
You're looking good here.
Everything is steady. Steady as a rock.
Okay. We're going to be busy for a minute.
Master Arm, On. Take care of the descent vent. I'll get the pressure
Ok, all Flight controllers, about 45 seconds to T-1 Stay/No-Stay.
taped intercom loop segment 4]
As we came down there, you heard the sixty seconds. We had tripped
low level, which no one ever expected to happen. When we tripped low
level, things really got quiet in that control center. We were nervous,
sweating. Came to sixty seconds, came to thirty seconds, and my eyes
were just glued on the stopwatch. I didn’t see it. The system
could have fell apart at that instant, and I wouldn’t have known
it. I was just watching the stopwatch.
Nance had it on a strip chart. I was the backup to Nance. I talked
earlier about backup to each other. He had a strip chart recorder,
and it had the low level on it. So as it moved down, it moved at a
certain speed so he could see much better than me, but both of us
were pretty close. We were waiting for that low level. We knew we
were very close to it, and the instant I saw it, it was on an event
light with a high data rate hitting it. So I saw it within milliseconds
of it hitting the ground and starting the stopwatch, and he didn’t
have to start anything. The strip chart measured it without him having
any action, so he was primary for this. You heard him report low level
and then sixty seconds and then thirty seconds.
When it got down and stopped, I had eighteen seconds showing on my
stopwatch. I’ll remember this little aside thing. I’ll
never forget, I looked at that and I thought, “You know, this
watch, I’m going to encase this in plastic and never touch it.”
So I took it back to the office and put it in the desk drawer and
thought, “I’ll save this for posterity.” Then I
got to worrying about it. I thought, some of the janitors, somebody,
will steal this from me. So I wrapped it up in a handkerchief and
carried it home and put it in a box and saved it. Sometime later I
got it out, looking at it, and I thought, “I remember that needle
was sitting on eighteen seconds. Now it’s on twenty-two.”
I thought, “Man, I’m losing my mind.” Well, a few
days later, I got it out and looked at it again, and it had changed
position again. I thought, “Ah-oh, something’s wrong here.”
So I jumped my daughters, and one of my daughters was twirler, and
she had been coming in and taking that watch and using it to time
her. [Laughter] So it lost its position.
Later on, I brought it in and sent it to the Smithsonian, and that’s
where it is today. I don’t know what they did with it. Probably
lost it. [Laughter] I run it back to where it was supposed to be,
and left it with the needle on the right thing. They probably think
it’s stopped just like the mission left it, but it ain’t.
I repositioned the stopwatch.
That’s what you heard. He reported the sixty seconds, thirty
seconds. That was from Nance. That was the Prop guy. You could hear
the interaction. You could hear me reporting to Kranz, and Charlie,
the Capcom, heard it. He instantly relayed it. So if you could go
back and time those, I also told you, we allowed a half a second for
reaction time, it sounded to me like it was pretty close. I’ve
never gone back to double-check, see how close our reaction times
all stacked up together. They reported it to the crew.
The way the crew worked, they knew their monitor onboard gauge, what
they were looking at, was approximate. You heard him say “quantity
light.” He saw the quantity light. He was saying, “I observe
the quantity light. Low level has been tripped.” But if you
just do it in your head, you will have no sense of how many seconds
were gone. He was depending on the ground, and he knew the ground.
He knew all the things we had put into it. They both knew, when you
hear in your ear “sixty seconds,” that’s how long
you, on board, have got until you’re going to abort. When you
hear thirty seconds, that’s how long until you’re going
to abort. And when you hear “abort,” you don’t think
about it. You do it. That’s how close we were to abort. We’d
been burning twelve minutes or something on that order. Ten eternities.
And it come down to about eighteen seconds of aborting. We were lucky
we made it. Just that simple.
I think that catches the things I wanted to point out to you. You
can go back and play it again and you would maybe hear better Nance
reporting and Bill Sturm reporting and the report to me and the flow
to the other team. You can see that team all working together. If
you listen to it the first time and you don’t realize the background
behind, it will just go right over your head.
Well, that’s kind of brought me to the end of time, guys. I’m
sorry. I wish I could just stay on with you, and I’d planned
to just be available as long as you wanted today, and this other thing
came up that’s out of my control.
I did want to point out that on that segment of the tape, of course,
you can hear yourself telling everybody to calm down, essentially,
and keep your eye on the gauges, but in the background you could hear
See, everybody went bananas. That was not the time. That was the time
to keep your eye on your business. You notice they settled down, too.
Did you hear them? They were very—that pulled them back.
So it’s a hard moment not to applaud.
I know it. It was. It was a hard moment. You know, I got goose bumps
listening to that.
I did, too.
Just gives me goose bumps every time. I know we’re going to
make it all right. [Laughter]
But we can finish that up next time.