1979: How to LAND ON THE MOON | Project Apollo | Retro Tech | BBC Archive

take a look at the command module, quite small for three men for almost 10 days, isn't that three sofas, the middle one usually folded for extra space? you flew the spaceship, you sat here at this control, how much power do you want? And with this one, what direction do you want to go in front of you? the control panel which way up are the computer engines, the fuel tanks and up here are the warning lights, so here you are in your spaceship, but where is here? That's the next major navigation problem. Most of the time, the large tracking stations on Earth would calculate how long it took to receive a radio signal from the spacecraft and use that information to determine the Apollo's whereabouts in space, but here, if something goes wrong, you're on your own and that's where this comes in, you see how one gyro stays the same up, anything that moves, now you put three gyros spinning and sitting like this, like this and like that, and they will feel the spaceship moving around them until the computer and so will three accelerometers that detect thrust the same way you know your head tilts back when a car accelerates.

Now the computer has a clock to know that we're going in this direction, we're going this fast in this direction and we've been doing it for X hours or minutes and it can use that to determine where the spacecraft is roughly for the really fine details. You use these things, a telescope and a seat, you point the spacecraft so that through the seat you see, say, Miami, then you ask the computer to find you a particular star and, while searching for the star with the telescope, you also tilt it. a little mirror back on the seat at the same time, okay, here's the star in the telescope.

Center it when you return to the Sextant. the stars also in the tilted mirror of the Sexton and because the optics are superimposed on Miami, the angle of the small mirror of the seon is the angle between St and Miami. Put that angle into the computer so you have this angle, do it again in another one. Star and Miami now there are several places in space where you get those particular angle relationships, but since the computer already knows approximately where you are, it knows which of those positions you are not in, leaving only the one you are in and that's how to get a solution in space seems easy uh-uh one day on the way home after having circled the

moon

and we were a little relaxed, I got a little careless and started using the program to start navigating and I accidentally put the program error which actually put me back on the launch pad I lost all reference to our position in space our attitude uh this was not in the flight plan uh uh they already know that we were we wanted to keep everything running this was the first flight and Naturally, we didn't want to lose our

land

mark because we couldn't get home safely, so everyone was pretty worried until I manually looked around the sky and found three stars that I recognized since the computer couldn't tell me.

Since which star was which and then I did a manual alignment of the platform and since then we were back in good shape. The next problem to solve was how the Luna module leaving the surface of the Moon would find a command module. after a 60M climb and perform the complex maneuvers to match position and speed accurately enough to perform this last move, which is accelerated in the movie with the kind of precision needed to hit the docking target, will tell you what we have captured there. Come on, we were there. So that's not as easy as it seems.

Suppose you are in the Moon module following the command module at the same speed in the same orbit to catch it. You start your engine wrong, which puts you in a higher orbit than him and higher orbits are slower orbits. Perversely, you should have done exactly the opposite, you started your engine as if to go straight away from him, which leads you to a lower orbit and the lower orbits are faster, so you catch up when you get to the side. The command module, of course, is below, so docking involves a series of very delicate mini-maneuvers, many of which are the opposite of what you think you should do, although the Luna module's computer will take you to Rendevu or to the bottom. to the surface of the Moon on its own, it will only do so if all the switches are in the right position to be told what you need to know and as you can see there are a lot of switches to be in the right position.

Of course, you can fly the LM yourself if you want to use these two controls, then the main computer shows which direction you are facing, how much fuel you have left and the one that everyone wants to see, very gently turns on that one, the lunar contact light. As you get above 500 feet, the job is to find a quiet place to

land

and land. The commander has 2 minutes to do it before he runs out of fuel, so he looks out the window as if his life depends on it. He does it and the Luna module pilot is telling him everything he needs to know from that screen that says you're going forward or sideways at a certain number of feet per second and this screen here that says you're going up or down. at a certain number of feet per second. so many feet per second, so it says things like 200 feet forward at 8 down at 5, the name of the game of course is to land on the surface of the Moon by going forward or sideways at n and down at a very small number, it seems easy. but as we watch the landing of Apollo 11 remember what I said about putting the switches in the correct position 50 down on 2 and 1/2 19 forward 3 and A2 down 22 feet 13 forward forward going down nicely 200 feet 4 and 2 52 just uh stop the landing there for a minute while I tell you about all the other people who were doing it too, the people the crew called Houston, they were about 70 and they were divided into four shifts, their average age was less than 30 years old and this.

It was his office the mission operations control room this is what everyone did gido the guidance and navigation officer remember it you will meet one Foo every maneuver of the spacecraft was his responsibility

retro

to bring it back safely to Earth here the flight surgeon here the capsule Communicator the astronaut in constant contact with the crew and here two groups of engineers, one observing all the systems on board the command module, the other observing all the systems on board the Luna module and all observing paying close attention up here, the hot seat, the flight director, the boss now while all you and I heard during the mission was the Communicator capsule talking to the crew here everyone was talking to everyone else on their own Communications Network internal call Flight Director Loop listen to what the landing was like that locked us up there, tcom, okay, it's a very weak FL, okay, how do you look, all your systems are working, it's a strong FL, how about do you control?

We look good, we guide you, the flight director in charge, whose voice you heard, was Jean Crunt. We came on board around 8:00:00 00 on the morning of July 20th and it was like everyone was ready for a big game. I think everyone had sweaty palms. They were a little nervous. We communicated with the other controllers to get more or less the general status of the spacecraft and it seemed that everything was going very well for us and as soon as a spacecraft arrived, the first thing we noticed was that our communications were very deteriorated, they were poor , they came and went and it seemed that that initial problem was necessary to mobilize the team to more or less the mood.

Hey, this is just another training exercise, we have problems, that's what we're training to work on, so let's do it, this is the orientation officer. I said you would meet Steve Bales, he was monitoring the navigation and therefore any involvement in the navigation by the Apollo computer. Unfortunately, we had started the limb guidance computer with a navigation error, it was about 14M per hour, what that means is the guidance computer. It is believed to be heading towards the Moon 14 million hours slower than it actually is. The only thing that could save the situation was an update to The Landing radar that told the onboard computer that it was wrong that the astronauts couldn't do anything to help the radar.

The flight looks good. at that moment I started to relax a little because the worst problem I thought we could have on a landing was a navigation problem just 20 seconds after I had started to correct the state Vector error occurred the first alarm of the program 12 122 alarm flight

retro

ir retro down 6 plus at alarm 122 that means the computer was too overloaded to do everything it was supposed to do. Bales had 20 seconds, if in that time the computer stopped navigating or there was one more alarm, he would have to abort the landing immediately. let's go to that flight let's go to that alarm Roger we got you we're going reur we'll go he's taking in do H now R roger3 you got the Accelerator Accelerate Down you were scared to death but I wasn't as scared during the alarms as I was but when we started the landing, what we had to do is make sure that if for some reason we had an accident during the actual landing phase, we had the information to tell us why an accident occurred, so communications and indeed telemetry They were extremely important.

What you're really saying is that if people died, you had to know why, we have to know why. That is absolutely correct. Okay, we still have landing radar guidance. Alright? converged beautiful has converged yes okay okay all flight controllers are going to land guide control retro Capcom we are going to land Eagle Houston you are going to land on rer alarm 121 alarm 121 of the same type we are going to fly the same type we Come on, one of The main problems caused by the five computer emergencies during the descent was that the crew were only able to look and see where they were in the last few minutes, so they weren't exactly happy that we were aware of some of the problems we knew we had a tight fuel budget, we didn't know the computer was going to act badly on us, as it did, the alarms had occurred because a Rendevous radar switch had been left on, flooding the computer with an overload of data.

We didn't even need during landing for a switch to be in the place we told the crew to put it. We hadn't been super smart if we had been super smart in the two or three months before landing and thought about this circuit. and I thought about what the possible implications might be, so we've caught it forward which is 40 feet down two and a half kicking up some dust 30 feet 2 and a half down shadow four forward four forward moving to the right a few 30 seconds 30 seconds had 30 seconds of fuel left contact light OK engine stop AA in decent control both Auto decent engine command engine arm override off 43 is in we have turned it off we copy it Eagle all T1 on standby T1 Tranquility base here the eagle landed Roger TW Calm down we copied you on the ground you have a group of guys about to turn blue we are breathing again thank you very much the eagle landed and I could see it here on my console I saw the altitude go up to zero I couldn't believe it, we trained, I said, oh my God, we did it, uh, Charlie Duke just then says you've got a bunch of guys down here about to turn blue, well, Charlie Duke could see me from his console position. and I always thought he was talking about me, but I always thought he said blue because Charlie couldn't tell that he had turned white as a sheet, which is the way I had turned.

I assure you that Slayton was director of flight operations in the The weather and deck were right next to me when we were in the final stages. The descent. Well, in fact, you were there the entire descent and we were relaying information back and forth and they went down, I think a few hundred feet. and after a minute they were still buzzing around the surface and uh uh and we were talking and all this information was coming in and I was trying to filter and finally the platform hit me like that and he said to shut up so uh He stayed on. silence and we just watched and then they started and I was literally holding my breath.

I can remember that I was personally and they landed within 15 seconds of an abort situation or maybe 20. I forgot exactly, but I was close and, at that point, where the eagle landed, and great, I forgot what I said exactly, but we have a group of guys about to turn blue, we are breathing again and I know I really was and I was very tense. at that time, but the people in the observation room and in our areas oftraining we could hear him cheering through the glass walls in the room here and that took a few seconds to sink in and then what we had to do is get back to business again because we had to make sure that not only were we down but we hadn't had any leaks in any of our thrusters so we had to start a countdown for two possible abort times, we had to change the computer modes and everyone was emotionally locked in, I remember at the last minute I was gripping of the handle of this TV and I just wouldn't let go and I had to change the comms loops and I couldn't talk and I finally got so frustrated with myself that I grabbed and slammed my hand on the console and that brought me back to life and for days I was bruised from wrist to elbow.