NASA’s longest living spacecraft were launched 40 years ago (aka are over the hill) and are still going strong. The voyager probes were designed to be long lasting through utilization of radioisotope thermoelectric generators along with backup systems and radiation shielding. They are 13 and 11 billion miles away at this point and it will be interesting the data they send back when they both reach interstellar space. What are you working on currently which could last 40+ years? What should we be working on right now (outside of physical buildings and infrastructure) which we should make sure lasts 40 years?