Sometimes the code i write doesn't work 6 months later – so I was incredibly impressed to read about the NASA team who reprogrammed the Voyager 1 space probe some 37 YEARS after the code was last changed. I can't imagine what the 40 hour wait between sending the commands and receiving the response was like.
https://rob.al/2Cy6MJW
The Voyager team is able to use a set of four backup thrusters, dormant since 1980, for orienting the spacecraft.