for former apollo aero flight controllers and engineers discuss the lunar module landing operations during the apollo 11 mission to the moon. this panel was part of an event john: good morning everybody and welcome to the 50th anniversary of the apollo moon landing. [applause] i will say that periodically throughout the day so that people will applaud. you can here that atmosphere is charged and the dingling in the background. [laughter] special day, very auspicious day. we are honored to have with us today a panel of important engineers. my personal heroes growing up. 14 when you all did the miracle in 1969.

i tried to get here as quickly as i could. we have a panel that is going to talk about lunar module landing operations. if you want to know what that is, they will tell you about it. the panel here is jack knight, bob nance, hal loden, and bill reeves. instead of me going on about them, i will ask them to identify themselves, say what they did, and open it up a little bit for questions. by the way, i am john charles, a resident here at space center houston. i would like to turn the microphone over to mr. knight. it's to talk about what you did here for apollo 11, what brought you here in the first place and your recollection of that important day. jack: i was the son of an air force family.

we went to various bases around the world. i went to the georgia institute of technology and graduated in 1965. i came directly to the manned flight center, in particular the apollo systems group. at the time i arrived, apollo had been a program in work, but we were flying the gemini and the gina vehicles. i was in the environmental control and electrical power area. i participated in every lunar flight, including the unmanned one. i was in the ss our staff support room for that. and on all subsequent flights i was in the operational control room, which recalled telcom or telview, depending on the flight. that was apollo nine, 11, and

everything had a lunar module on it. i will pass it to bob nance. [applause] bob: good morning. this is a big day. started this morning with a prayer just like 50 years ago. lord, help me not screw up today. [laughter] my name is bob nance. 50 years ago, i heard president kennedy tell america we were going to go to the moon by the end of that decade. i wanted to be part of that. everything from then on. i also went to georgia tech. i met astronaut john young there. then i ended up from georgia tech to be in the manned spacecraft sooner in lunar module propulsion. that i got toed

therey dream of sitting on the console of lunar module propulsion when we landed on the moon. i think we will talk about that later. [applause] hal: good morning. my name is hal loden. i grew up the son of a memphis preacher. i worked -- 1964. a good friend of mine said go to houston for the spacecraft center. i said my wife is from houston, that would be good. i got a job at msc, at the time. i went to the operations directorate. that was the gemini-gina systems.

to back up a second, i an am electrical engineer from texas a&m. [cheers] hal: [laughter] anyway, during apollo 11, i was a flight controller in the lunar module gnc systems. that area comprises of the dissent engines. the landing radar, the rendezvous radar, and the primary and backup hardware for the computer systems. i flew the apollo missions from glen 1 in australia for that. apollo nine, through 10, 11, all the way through 17. specifically on apollo 11, i was the main control guy on the

console for the ascent on the moon. the descent was exciting. i was there with -- who is no longer with us. he passed away a couple months ago. i was hesitant as to whether or not we would make it when bob was calling out the fuel remaining. we didn't have a lot left. when we got to the ascent, we had problems too. i have heard people say that the acscent was more dangerous. i find that hard to believe. anyway, that's my story. i'll pass it to bill reeves. [applause] bill: good morning. my name is bill reeves. i grew up in arkansas and went to oklahoma to get an electrical engineering degree and went to texas as fast as i could.

in football season, i didn't have a chance growing up in arkansas. when i was hired on in 1967, i was hired on as the flight controller operations director. we were in charge of all of the power systems and the power distribution systems. we were also in charge of the pyrotechnic systems, the explosive devices that separate the stages and open valves and deploy the landing gear. i had gotten here right after the apollo 1 fire in january.

the program was in a delay while they figured out what had happened and redesigned. it turned out to give me the time i needed to get on board. i was lucky enough to be in position when we started flying the lunar module. i was in the staff support room. the support rooms are the rooms that support the main control room. we are the people who make the people in the main room look good. [laughter] when you see the control center, when you see it on the movies, that is the tip of an extremely > large iceberg. there are a lot of people supporting that. i was flight controller on the lunar module throughout the

entire program for all of the flights. after apollo was over, i flew back seat for nasa for about eight years. i came back for the shuttle and was flight controller on the shuttle and was elected as flight director for 22 shuttle flights. that's it. [applause] john: this is excellent. a good thumbnail sketch of the lunar activities for apollo. i am derelict in my moderator duties. when we are finished here, please move quickly to the exits. there are 200 more people outside waiting for the next presentation. with that out of the way i would , like to ask a couple of questions and we will open it up for q&a. i would like to talk about the two significant lunar propulsion events, the descent and the ascent. i would like to start with mr.

nance and talk about your recollections, any trepidations you had about the lunar landings. the power propulsion from lunar orbit and your recollections and thoughts about the probability of success, inevitability, or any sweaty palms you might have had. bob: there were many sweaty palms. that is a broad area, but let me try and give an overview. modulef all, the lunar dissent starts shortly from when the lunar module comes from around the backside of the moon. the biggest problem we had was the data was so difficult that gettinghaving trouble voice and data, particularly high gain data. as we started the descent, the data dropped out. so we are sitting here giving

go's and no-go's without data. i know a lot of times, you hear the landing and it sounds like everything went really smooth, at thewas difficult beginning. the data would drop out, we would get a little bit, then we got the data back. then we came to the yaw, where the crew starts with their head down so they can see the surface. as they lean over, they rotate 180 degrees. when that happened, it seems we lost data again. at first, it seemed, are we really going to be able to land like this? the great news was we started getting good data and everything was looking good. we did hear that we would be long. we knew that from the beginning. that had to do with a slight timing error. but everything was going very, very smooth. was in charge, i of the ascent engine and

reaction control, the thrusters that you see on the lunar module. a lot of people think, you are just concentrated on the dissent engine, but we actually had to have a visual pattern where you looked at the ascent and rcs, because you are burning the engine and the vehicle was shaking. you want to make sure that if a decent engine was working good, whether the ascent head was springing a leak. even though you were concentrated on the dissent, you constantly had to look at the other various propulsion systems. we started off burning at about 98%, and then it dropped. it dropped at six minutes and 25 seconds. by then we had data and everything was looking pretty good. everything is tracking. we had some computer problems, the overload on the computer, but everything seemed to settle down, everything was going well.

one of the things we were worried was that the field 4.5%n, it was running propellant remaining. it was looking pretty good. heard attitude hold. that is when the crew decides to take over themselves. normally if they did nothing, the lem would come all the way down to the moment before landing. we already knew with simulations that neil liked to take over early, but this was earlier than we had seen. one of my jobs was the propellant monitoring. are we going to run out of fuel? we had a meeting with neil and buzz and worked out what we would do. we first had an indication of low-level which is 6.5% -- 5.6% propellant remaining.

the goal was that you know how much time at that point you have to hover. what we got to 4.5% and they were not close to hovering. neil realized he had to go over the top of a crater and to get away from a boulder field to try to find smooth ground. we could see this happening because the rcs, those jets, normally a descent engine has a bell. that means he is overwriting it putting in a command greater than the descent engine can move. he had leaned over to speed up. when he stopped descending, he leaned down and went up a little bit. i'm sure that was to see whether he could find a clear spot. the next one was 60 seconds.

that is 60 seconds until you run out. the calls were 60, 30, and bingo. 60 seconds, 30 seconds, and bingo. as i mentioned in the meeting, we sat there and my original idea was 60, 30, 15. buzz was active in everything. neil was always very quiet. after quite a while talking about this all of a sudden neil , said, i don't like abort. i'm a pilot, i'll make that decision. i said, we know that you will, mr. armstrong. [laughter] said,turned around and he "can you give that another name?" i believe buzz was a navy pilot. he said on an aircraft carrier when you are committed to land, you have to land no matter what, you say bingo. neil said, bingo works. was 60, 30, bingo.

the problem with that was i never expected to call 30. in simulations, we usually landed shortly after 60 seconds. i have a website, robertnanceapollo11.com. i have all of those tapes. you can hear the ss are talking to control -- the ssr talking to control. when i made the 60-second call out that was passed on, it was 60 seconds. when i made the 30 second call out, it was like i couldn't believe it. we finally landed with 22 seconds of fuel remaining. we hadtion to all that, a problem that is a story for another day. the interesting thing about this, it's really important that the public understand just how brave neil and buzz were.

there were so many things. this was the very first time we had ever landed any spacecraft like this. all of the other missions you had probably heard about, the ranger, the surveyor, they landed directly. you couldn't do that with men on board. if anything happened, you had no way to stop it to start back up. so we landed it totally different started it by going , down slowly. these computers had very little memory. this was the first time that was ever done. if you want to applaud somebody, applaud neil and buzz. it was amazing. [applause] john: skipping over a lot of interesting stuff, i would like

to ask mr. loden about the powered ascent back to orbit. tell us about the unique characteristics of the ascent propulsion system. hal: let's see what i can come up with here. 50 years as a long time ago to remember all the details. remember, during descent, we had those 12:02 and 12:01 alarms that gave everyone concern. that's because the onboard computer was being overloaded with tasks it did not need to be doing. it had to do with a rendezvous with the radar. when it came to ascent, there was quite a few crew checklist changes that had to be made to take into account that potential problem again showing up on ascent.

we want to keep those alarms -- we did not want that to happen. we want to keep those alarms from happening. once the changes were made, we came up with a procedure to stall the rendezvous radar antenna and power it off during ascent. there was another issue that i remember working. when they came back in from the eva, buzz noted the circuit breaker panels on both sides of the lunar module, and they are not like the ones you have at your house where you flick it like a light switch. these are circuit breakers where you push in and pull out. these circuit breakers, most of them were already out, which is in the off position. he got backed once in the lunar module, a circuit breaker was broken off.

it happened to be the ascent engine arm circuit breaker. not doesn't mean we are going to be able to light this engine. we have two ways of doing it. that allowed the computer to one automatically light it. we have a manual way to work around it with another push button. we were trying to figure out what to do. as i understand it, he took out his trustee, government issue black ballpoint pen and pushed countdown atthe the right time for ascent. on other thing that occurred the propulsion system, the fuel tanks, we had two pressurization bottles for redundancies to pressurize the fuel tanks. you have to get everything to the right pressure before it goes to the stress chamber.

during the simulations normally, we operated valves to pressurize the fuel tanks. normally, we would always see both of those tanks drop a couple psi, or pcm counts as we called it. that would confirm both valves had opened. when it came time to do it on the lunar surface, and they fired the valves to pressurize the ascent engines, i only saw one bottle drop, which raised the possibility we only had one bottle of pressurization on the fuel tanks. the normal procedure for ascent was assuming he had both bottles. we had the ascent engine and the rear thrusters. we had a system interconnect. they had to both use the same propellant. we could use the ascent engine propellant.

if we only had one bottle of pressurization, we had to terminate that. we had to alert the crew before liftoff that it was a possibility. we only had one bottle that would pressurize. the countdown to zero zero was done by the computer. the procedure also calls for shortly after takeoff, they would hit this override button, which circumvented the command coming out of the computer, just in case the computer went away for some reason. at liftoff, i told flight, we have both bottles.

very relieved about that. i want to continue on with the ascent feed. i noticed that they had not hit the engine fire override, the second way to keep the engine on. about halfway up, they finally energized the backup route for keeping the engine on. those were the things that occurred for me during the ascent. it wasn't very big, about four feet tall. i about three foot in diameter. at the ascent stage, it weighed about 10,000 pounds. it did its job very well. you notice when you are up the window on the films you see it rocking back and forth. that is the dead man on the altitude control system. those thrusters are keeping that

in that dead ban. the ascent engine was not give a ball like the descent engine was. once we got back to orbit, they docked with the command service module and discarded the eagle which impacted on the moon after they left the moon. a very good engine. very reliable engine. i was grateful to be part of such a great event. thank you. [applause] john: before we leave that topic, how many test firings to the ascent engine have before the flight? hal: that is a question i don't know the answer to. i would assume it had a lot of test and firings, as well as some in the backup chambers as well.

-- vacuum chambers as well. both the descent and the ascent engines were thoroughly checked out. the descent engine with the throttle capability, that was something we had never had on a spacecraft before. the people who put these machines together were very dedicated. that is a part of the iceberg that bill was talking about. the people who built these spacecraft and the components that went into the spacecraft, those are the ones that made it happened. john: that wasn't a gotcha question. there is a particular aspect i would like you to know about. jack: this is not my area, but i have read quite a bit of things over the years. it is part of nasa's development process when they felt there was an area that was highly risky,

they would hire two contractors to work on it in parallel. so there were two different contractors working on the ascent engines. finally, you got to the point where one of them was more successful or successful enough then nasa said you are it. , you can build ascent engines. one thing about the ascent engine was that its injector was such that the erosion during the firing was so bad, they could only fire it once. testing until of you certified that, but after that, no ascent engine was ever testfired before it was used for launch. a differentrobably story, but it's a different story on the ascent engine. it is a simple engine. all you had to do was get them to mix.

it would work. we knew from testing that it would work at least once. [laughter] and that is all it had to work. hal: that is a good point that i had not remembered. the first time we lit that sucker was on the lunar surface. that is pretty risky when you think about it. >> i was in a meeting for our simulations. i remember neil saying why didn't we just put a big lever on the side. the engine looks like a seat in the middle of the lunar module. he said why didn't we put a big handle on it where you turn it and it starts? [laughter] hal: that would not necessarily have worked for an abort state during the power off sequence.

-- power descent. he had another thing. bob mentioned the calm. when the lem came around, they -- the engine was essentially pointing towards the earth. to high gain antenna had point through the landing gear. one of the things that was added late in the game was the deflectors on the descent stage that were right underneath the down firing thrusters. they were added late in the game because the thermal analysis said there might be enough erosion caused by those thrusters that it would damage thermal protection on the descent stage. so you put the little deflectors. because it was late in the game,

those were never included in the modeling of antenna pointing, and getting good communications. so the comm guys, i'm pretty sure that's what happened. when you started the descent engine, as you were coming around, the antenna was essentially trying to point through one or more of those deflectors. you had this until you moved the vehicle a little bit and appointed the antenna. because neil wanted to be looking down at the moon, you had this other maneuver he was talking about after he started the descent engine. he ran it awhile and you had to yaw it over, so when it pitched forward, armstrong and buzz would be able to see where they were going. all subsequent flights, they didn't need to be looking down. they could get into their anticipated position, and then all they would have to do is pitch forward.

you would not have to have a yaw maneuver. that is probably why we ended up with comm problems, until they had pitched forward enough across the surface that the antenna got good enough comm with the ground. hal: this was the first lunar module that had those reflectors installed. the reason they were installed is like he said, the thrusters would fire, it would impinge on the descent stage. there was an impingement maximum of 15 seconds on the descent stage then we would have to terminate the flight. so these thrust defectors eliminated that problem.

on apollo 11, it would have we wouldthat limit, so have probably aborted if we had not had those stressors and reflectors on there. bill: there were a lot of great neil armstrong sayings throughout this thing. one of my favorite stories, people remember things differently but this is the way that i remember it, late in the game with the landing radar, there had been some problems in testing. there was a lot of concern about whether it was going to be giving them the data that they needed. they had done a lot of testing on it. we were in a flight rule meeting. i remember it like it was yesterday.

it was a large room with a lot of people in it. it was a long and white table. neil was sitting at the end of the table. there was a discussion about developing a flight rule that said if the computer was not accepting landing radar data by x altitude, then it would be an abort. they targeted for three hours and finally gene says, we have talked about this long enough. that's the rule. if the computer is not accepting radar data by x altitude, it's an abort. everyone was nodding their heads and neil was at the end of the table shaking his head. all of a sudden kranz saw him and said, you don't agree with this? neil said, you must think i'm going to land with the window shades down.

[laughter] bob: i think that is the only mission rule meeting that i remember. hal: i don't remember them because there was nothing but smoke. [laughter] john: we have time for a few questions from the audience. please shout it out succinctly and i will repeat it for the c-span audience. how far downrange to the land from the intended site? bob: it was about 3.7 miles. i was looking all of this up in case you asked. i didn't know it away could go. i did i put it on the website if

you want to look up that kind of stuff. >> [inaudible] john: compared to the smartphone, how much computing power did we have back then? bill: one picture on your cell phone has more bits in it than that computer on the lunar module. >> [inaudible] john: why did the lunar module carry jumper cables? did you know that it carried jumper cables? hal: i guess we had diehard batteries on board but we didn't need them. >> if our batteries didn't work, none of their stuff wouldn't work.

there weren't any jumper cables but there were some cables that went between the lunar module to -- between the command module and the lunar module. we powered some heaters for the two or three day trip to the moon so you wouldn't use any power out of the batteries that you needed for the lunar module on the surface. those are the only cables that i'm aware of. hal: those cables, they kept the heaters going on our inertia measurement unit. the platform where you could tell where you were in space and when you powered it up. those cables came to be very important on apollo 13. we were able to use lem battery power to recharge the reentry batteries on the command modules so they could reenter safety.

>> [inaudible] john: why was the lander so far off the lunar surface when they landed? bob: with the landing gear the original intent is that it would automatically land. what was going to happen was that when these probes that were about four-feet tall were to hit, it would shut the engine off and it would drop. we learned quickly in simulation that that was not what neil had in mind. as a pilot i would not want to have done that either. none of the apollo landings were anywhere near as strong, but if the engine had quit at 10 feet, the lem was designed to survive that fall. john: survived by stroking the landing. bob: it had a honeycomb that would compress. you did not want the lander to ladder to stop it

compressing. bill: there was no spring or anything in the landing gear. it was a honeycomb aluminum structure inside the tube. it was a one-shot deal. it would crush, and the strut would compress. he landed so light that it did not compress very far. that is why the ladder was as high as it was. >> [inaudible] john: who was responsible for picking and packaging and mounting the u.s. flag? the top is straight because of the support arm. what about the bottom? hal: my recollection of that is that was designed by our tech services division here headed by john cocker. they came up with the concept of unfurling the flag with the support at the top and letting it hang in lunar gravity.

that was compressed into a small package to afford us the volume. -- before it was deployed. we fly one in our control center just like that. the one we had in the control center is now on the moon. on some mission they took it from the control center and flew it to the moon. it is just like that. >> on the training vehicles, didn't armstrong typically land with 20 to 30 seconds of fuel line? john: did armstrong always have the equivalent of an excess of fuel at the landing? bill: one of them he didn't land. he ejected out of it. [laughter] bob: i think that is right. you would leave for some other reason or an engine problem, so

we never really -- the normal landings always had 4% or 5% remaining. >> [inaudible] john: let me report -- repeat the question first. the question was it is called mission control but who is actually in control? is it the people on the ground or in the spacecraft? bill: control covers a lot of ground. the crew could manually control a lot of things within the vehicle. what the flight ops is

constantly doing is keeping track of the flight plan and any changes to the activities that were going to do, and any changes to procedures and working on any anomalies that might occur with the spacecraft. it is a joint effort between the crew and the ground. you are constantly going back and forth. bob: in those days we did not have a lot of the command capability that we have today. you would put together procedures and the crew would work through the switches. today a lot of that is done by command from the ground. hal: do you mean who is an in ultimate command of making a decision? >> i would like to know how much control was on either end. jack: the ground computer complex did almost all of the trajectory calculations and sent

up a set of numbers to the spacecraft which they entered into their computers. without the ground, they would not have had enough computational power to do the whole mission. but once you got into power descent, there was nothing the ground could do if the crew wanted to keep going. if that's what you are talking about. what if the ground called abort, there are chances they would abort because they would assume the ground saw something that they could not see. >> i think another part of that is that in mission control, it in a timeght erector critical situation, makes those decision based on his team on the ground. the overall decision to recommend the abort comes from the flight director and goes from capsule communicator to the

crew. hal: there are three consoles that have the abort switch on it. bob: that was almost always associated with the launch vehicle. john: we have time for one last question. >> what was the biggest crisis of the whole mission and how did you solve it? john: that is a whole nother seminar. that's a whole other lecture. can somebody answer that in five words? jack: my guess would have been the 12:02 alarm. the first one. it was unexpected. it was not a normal thing. we had done it in sims, but nobody really expected it would happen. because of the simulations, it set up a situation. we had done a bunch of research to figure out what alarms would be a real problem and which not.

jack garwin had a list that he worked out with m.i.t. who did all of the programming on this thing. >> seems like the only time neil was nervous is when -- [inaudible] jack: again, unexpected. during the simulations, he had punched out. he had aborted when he got that alarm, but since we had all those discussions and reviews, he decided it was ok. bob: that points out that the real unsung heroes, and there are so many all over the country, but the simulations guys were amazing. they had to not only learn the systems, and how they looked at our procedures, but to find errors. -- try to find areas. in the last sim, the 1201 came up. that was the emphasis for

looking into that. that is a perfect example of the teamwork that it took to pull this mission off. hal: another way to describe the simulations people, they were very devious. [laughter] john: on that note, thank you for being here and thank you to these panelists. [applause] [captions copyright national cable satellite corp. 2019] [captioning performed by the national captioning institute, which is responsible for its caption content and accuracy. visit ncicap.org] announcer: and now you are watching american history tv. every weekend, beginning saturday at 8:00 a.m. eastern, we bring you 48 hours of unique programming exploring our nations past. american history tv is only on c-span3. announcer: in 1979, a small

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