system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do large and complex projects - e.g. the James Webb Space Telescope (JWST) - keep pace with, and accommodate, technological changes over extended design and build periods?

For example, JWST's control systems originally designed in 1992 would, I'm sure, look very different to control systems designed today. Will they have been updated multiple times along the way?
gpt
Systems might be updated during multiple rounds of the design process, but at some point the technology is locked in, which is essentially the same as a freeze in software engineering. At that point, no further changes or updates are made even if new technology becomes available unless it's to fix some problem that comes up in testing. Things that go into space are very expensive and once they're up there, there's no way to swap parts or change or fix things, so you want something that as reliable as possible, which pretty much always means something that's been around longer and has time to have been extensively tested and have had all the bugs worked out. Reliability is what's most important, not what's newest.