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Building an Apollo Simulator
For two years, I’ve been working to program and build a complete Apollo space flight simulator to use in my physics classes. When I say “complete,” I mean not just a computer program that lets you fly, but a mock-up of the spacecraft control panels and the entire Mission Control, as well.
I’m a physicist, and I do a lot of computer programming in my research, so I started with writing a Python language program to handle the physics of space flight. The basic idea is that, given a starting position and speed, you add up the forces acting on the spacecraft (gravity, atmospheric drag, engines), and from that you get the acceleration. That gives you, in turn, the new position and speed. Step the clock forward a fraction of a second, and repeat. I have a lot of computer engineering students in my class, so it fit naturally with the lessons.
I was able to write the main program by myself, but I wanted more than just a few numbers dancing around my laptop screen, accurate though they may be. I needed a view out the window, switches to control the spacecraft, and terminals for the flight controllers down in “Houston” to watch the telemetry. The graphics and networking were something I’d never done before, so I hired one of my students to handle all of this.
The view from the astronauts’ seats.
For the spacecraft, I built a control panel out of whiteboard panel and borrowed toggle switches and lights from the Engineering Department for the most basic flight controls: abort, engine, parachutes, attitude, and stage separation. They gave me an Arduino microcontroller to connect them to the simulator (more programming for my student). My student set up graphics for the earth, moon, and stars, so the astronauts would have a view out the window, and he put in a display for the Apollo Guidance Computer. Finally, I printed out a full-sized poster of the actual Command Module control panel to give them more sense of being in and surrounded by the spacecraft.
Mission Control was easier, in a lot of ways. The flight controllers only need to look at telemetry—numbers and plots—no fancy graphics, but we had to figure out how to send all of that from my laptop, over the network, and get it to display, live.
The last component was the Mission Planning and Analysis Division, who works out the orbits and the plans for maneuvers, to get the crew out to the Moon and back. That meant a few more programs from me that would let the students design the orbit, and I had to test it out myself to make sure I could put the whole flight together.
Finally, I had to write up manuals and procedures for everybody. The astronauts needed to know how to handle maneuvers and reentry. The flight controllers had to know what problems to look for and when to call an abort.
I had originally planned to have it ready for next summer, on the 50th anniversary of the Apollo 11 moon landing. But I started to realize that it was coming together faster than I expected, so I pushed the date up and committed to having the class carry out a round-the-moon flight (a recreation of Apollo 8, without any landing) this semester. Last month, I finally had it ready to go, and we had a launch.
View of Mission Control
I split the class into two teams, Red and White, who would take separate shifts and assigned each of the students to a role I thought they were well fitted for. Astronauts and the Flight Dynamics Officer (FIDO) had pretty hefty duties, so those went to some of the best students. CAPCOM (capsule communicator, the only one to speak directly to the crew) went to the chattier students. Others were more flexible in the assignments. In the view here, Red CAPCOM is talking through a walkie-talkie app to the astronauts.
My Mission Control security badge
You might see green badges on the students’ shirts. I made a fair imitation of the original Mission Control badges using Powerpoint, typed their names on them with my manual typewriter, and laminated them.
So how did it go? Pretty well, considering it was our test flight. A real crowd turned up to watch us. We had two launches and two reentries. The first launch went smoothly, mostly because of the bug that kept me from creating the engine failure I was trying to slip them. The second time, I gave them one engine failure on the second stage. The Booster Systems Engineer caught it and said we could continue on the other four engines. Then I made a second one fail, and he correctly called an abort. This caused some excitement, and I could hear the astronauts (in the same room with us for practice runs) frantically hitting the abort switch.
The first reentry had a real—and unplanned—switch failure that made the crew skip out of the atmosphere, because they couldn’t roll the spacecraft into the correct orientation. The second reentry was very smooth. As they entered the radio blackout (I’ve made the simulation stop sending data to Mission Control as long as it lasts), we heard a phone buzz. It was a telemarketer calling up one of the astronauts! That relieved some tension in the room, as people started joking about it. I remarked how impressed I was that they’d gotten the call through the ionization blackout. Perhaps we should hire them to handle communications. Finally, the crew opened their parachutes and splashed down gently in the Pacific Ocean.
Everybody had a great day, even though we didn’t wind up with enough time for the actual flight around the Moon. So I’m starting up a Spaceflight Club to give us more chance to practice the flights and carry out a full mission. I’m getting Engineering to machine a full-scale, realistic control panel. I’ll have all of the dials and switches of the real spacecraft, and it will be painted up to look like the original. By this coming summer, this is going to be pretty fantastic.
Published in Education
Oh, I’m enjoying this. Don’t apologize! This is what makes Ricochet so much fun; the comments are giving you more information and entertainment.
Sure! In principle, we can run groups already, but I’ll be putting the word out here when the super-duper control panel is ready. If you’re in southern Ohio, we’re at Shawnee State University. Come on by, and we can set something up.
If you—if any of you—are considering going to Green Bank Observatory (West Virginia) for their Star Quest event in June next year, my wife and I give talks there, and I’ll be bringing the whole simulator over for complete flight sessions! It’ll be near the 50th anniversary of the Apollo 11 moon landing. Hope to see some of y’all there.
Hey, I was in the seat to your left when I was in Mission Control! It was August of 1986, and NASA had suspended flights in the wake of the Challenger accident. The movie Space Camp had come out that summer, and a French magazine was doing a story on the real Space Camp. During our launch countdown, the photographer had his camera on me, and I rather consciously crossed my fingers in a way that showed up in his viewfinder. I never knew which magazine that was; I’d have enjoyed seeing if the photo made it in there. The only drawback was that I was still in my bowl haircut at that age.
@timh, here’s a question that you might’ve covered, but I don’t remember seeing it:
You put students in the position of astronauts/mission control and have them work through the mission, which–as I said above–is a dose of just pure awesome.
What tools do they have at their disposal?
I’m thinking proficiency with slide-rules is about as robust as proficiency with buggy-whips. What IT (etc.) do they have at their disposal to work the mission calcs?
If the students don’t have full-spectrum IT, do they resent that? Or gain a deeper respect of the knowledge and skills of the original personnel?
As some of you know, I attended the Vanguard 1 50th and 60th celebrations at the Naval Research Lab in 2008 and 2018. I’ve put together the transcript of the 2008 meeting which included comments from then NASA head Mike Griffin and four Vanguard veterans. There’s a lot of info about pre NASA launches. Unfortunately, I’ve never gotten permission to publish the transcript. But if anyone’s interested, PM me your email and I’ll send it to you.
Hi, Boss Mongo—sorry its been a week since I’ve been checking the site and am just now getting to this.
This is a good question!
The actual orbit designers of the Apollo program did use NASA’s digital computers to plan out the trajectories. Gene Kranz’s book, Failure Is Not An Option, has a funny story about a rogue group organized by Jack Schmidt (Apollo 17), working out some bold ideas for dark-side-of-the-moon landings. They were using the Mission Control computers during off hours, kind of sneaking their orbit calculations in there without permission. Of course, preliminary work can be done with charts and graphs. My orbit designers are using a set of Python programs I wrote for the purpose, which will do pretty much the same calculations the Apollo-era programs did, only much faster. We’ve got a few hours to run the whole mission, after all, rather than a week. Because the actual calculations and rules for these are more complicated than I have the time to teach them (this is only the first semester of freshman physics), I’ve simplified some of the problems and given them a more limited range of options. We’re assuming that the Moon is directly over Earth’s equator, and neither of them rotate or revolve.
That’s where the heaviest calculations came in. The flight controllers were generally more involved with individual systems and would be looking at status indicators and strip charts more than calculations. For most of them, I think math was kind of incidental. During the Apollo 13 accident, Sy Liebergot (White EECOM) was looking at the oxygen and fuel cell readouts and from the rates at which they were decreasing, he was able to predict when they’d run out. That’s a straightforward calculation in principle. So far, I haven’t implemented that level of sophistication in the failure options. Given time, though… ;) I’ve thought about working out some nomographs (remember those?) for them to make quick calculations of formulas. I’ve got a whole book on designing them.
But in general, I’m not limiting their computing technology for problem solving. We have a short time to carry out the simulations, and I’m working with introductory physics students, so I feel it’s an acceptable trade-off.
Hi, Richard,
That’s fantastic. I’d love to get a copy. I’ll send you a PM though the site.
Uh, no. No I don’t. Thanks for the link though (I kind of peaked in physics at understanding F=MA; it’s worked for me thus far).