One of the most complicated machines ever built was the US space shuttle (technically, the STS or Space Transportation System). Despite the title, we doubt anyone is going to duplicate it. However, one of the most interesting things about the shuttle’s avionics — the electronics that operate the machine — is that being a government project there is a ridiculous amount of material available about how it works. NASA has a page that gathers up a description of the vehicle’s avionics. If you are more interested in the actual rocket science, just back up a few levels.
We will warn you, though, that if you’ve never worked on space hardware, some of the design choices will seem strange. There are two reasons for that. First, the environment is very strange. You have to deal with high acceleration, shock, vibration, and radiation, among other things. The other reason is that the amount of time between design and deployment is so long due to testing and just plain red tape that you will almost certainly be deploying with technology that is nearly out of date if not obsolete.
A good example is the orbiter’s GPC or General Purpose Computers. There are five of them — at least three have to agree before they’ll do anything. Early versions of the GPC used magnetic core memory. That technology was old even when it was put in the design but it was the best way during the design phase to ensure the memory would not be upset by radiation effects. In 1991, a major upgrade did replace the core with semiconductor-based memory.
The information on the NASA site is a bit high-level but still detailed. If you want some real hardcore discussions about the shuttle’s avionics, the KLabs site lost NASA funding before moving to a private web server to remain operational. If you ever wanted to try your hand at programming in HAL/S as the shuttle programmers did, you can get the documentation there. There’s also a booklet with a lot of information that you can download from NASA and a video overview you might enjoy, below.
While we doubt anyone will be trying to build their own shuttle, this is still a great wealth of information. Of course, the Russians did try, back in the day and arguably made a better system. If you do build a copy, there’s already a shop manual from Haynes.