Eidophor Memories

This interesting YouTube video was brought to my attention yesterday, and it brought back lots of great memories of the old Mission Control Center that got me to reminiscing….

When I showed up at JSC in 1980, the control center was using much of the same technology as it had developed and used during the Apollo program. The old green consoles were being fed data (and controlling) the big computers on the first floor, and the large displays up in front of the room were still being shown by a large, dedicated – and complicated – projection system in what we all called “the Bat Cave”. The Bat Cave was a spacious room crowded with all sorts of stands, mirrors, and projectors, most of which you couldn’t see very well because the entire space was painted black and the lights were rarely on. You entered the Bat Cave by the double doors on the far-right front of the room, and could continue on to another room beyond. We rarely wandered around in the Bat Cave itself because you could trip on something in the dark and probably mess up something expensive.

This video is interesting because the person who does it (very well, I might add) approaches it sort of like an archeologist might. She has pictures from the Apollo days, and a couple of drawings – plus a document that was written in 1989 by a contractor who was asked to propose a modernized system for the projection system.

As part of this proposal, they wrote up a few pages of how the old system worked. It was a wondrous amalgamation of old optical projectors, plotting systems, mechanical trackers and cooling devices which prevented the large, expensive bulbs from melting. This system was in daily use well into the Shuttle years, during most of my career as a flight controller and then into my early years as a Flight Director. We threw around the term “Eidophor” for the side displays, which referred to a special projection system for early television images that actually only worked on the rightmost screen.

The fact that this YouTuber couldn’t go back to the original source documents that created the system – and that we read as workbooks describing how the displays worked – is simply an unspoken comment on how bad we all are at documenting what we actually do on a daily basis. Yes, she was trying to piece together what happened from just 50 years ago, much as an archeologist has to piece together the story of an ancient civilization from a few pieces of bone and some pot shards in an old fire pit. We might THINK we do a good job of documenting what we do every day, but evidence like this says that we really don’t. We can’t for instance, simply go to Boeing and have them pull the construction drawings from their Rockwell (North American) files to build an Apollo command module. No one today actually knows how to do it anymore.

This video does a great job of describing what will seem to many to be a Rube Goldberg system of scribes, multi-layer projection, and plotter projectors to give flight controllers a simple image of a spacecraft moving on a map. And yes – it all actually worked just the way she describes. I have, somewhere in a box, an old glass slide (maybe 2 inches square?) with a metal coating that was used to scribe orbits of the projector. In the old days, you’d sometimes see a new map pop up, then a set of orbital paths would start appearing, but the scribing device would get hung up, and the beautiful sine wave would die off in a squiggly line dropping off the right edge of the screen. The orbits would go away, and a fresh set would be drawn – you could imagine a technician back there in the Bat Cave trying to tap and prod the scribe to start working properly again.

Not that we didn’t have similarly entertaining situations once we went to a front projection system. The first front projector systems we had were big, boxy machines, the size of small refrigerators, hanging from the ceiling of the control room. They were finicky, and took time to warm up – and sometimes had electrical issues. I remember a simulation where the Prop officer shot up from their chair and almost jumped over the console behind them as smoking, molten insulation started dripping onto their console from the projector overhead. There were sparks and flames, with a few flaming bits falling onto the console below before the Ground Controller got power removed and a fire extinguisher deployed.

But that was in the future compared to what is described here as “the early days of Mission Control”. If you’re interested in the history of technology, it is worth taking the time to watch!


The Apollo Mission Control had state-of-the-art, large displays in the front of the room — but what was behind them?

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