On June 13, the Hubble Space Telescope took itself offline due to a fault in its payload computer, which manages its scientific instruments. Since then, NASA has been doing the sort of troubleshooting that might be familiar to many of us—with the added twist that the hardware is irreplaceable, in space, and about the same vintage as a Commodore 64.

So far, controllers have managed to figure out a number of things that are not at fault, based on attempted fixes that haven’t worked. They’ve narrowed the problem down, but they haven’t pinpointed it. And, at this point, the next steps will depend on the precise nature of the problem, so getting a diagnosis is the priority.

If at first you don’t succeed…

The hardware at issue is part of the payload computer system, which contains a control processor, a communications bus, a memory module, and a processor that formats data and commands so that the controller can “speak” to all the individual science instruments (this also converts the data that the instruments produce into a standard format for transmission to Earth). There’s also a power supply that’s supposed to keep everything operating at the right voltage.