Originally Posted by JayUtah

The DSKY displays were OTS 7-segment electroluminescent units, not light-emitting diodes or liquid-crystal displays. They're based on the principle that you can get just anything to glow if you shove enough voltage across it. They bear more resemblance to the tube displays called nixies. They really aren't affected by vacuum. They aren't much affected by cold either, since they work by running pretty hot. You can cold-soak those things forever and then just fire them up. The thermal ramp-rates were hundreds of degrees Celsius per second.