The Voyager probes are amazing in many regards but they may ALSO be the longest continuously running computer programs (by some definitions). Each probe has three computers each of which has a backup. I wrote this eight years ago for MIT Technology Review: https://www.technologyreview.com/2015/08/06/166822/what-is-the-oldest-computer-program-still-in-use/
Discussion
For more on Voyager probes, see these many articles I wrote about them, including an interview with the original and long-time project lead, Ed Stone. https://glog.glennf.com/blog/2017/8/4/if-you-love-voyager-like-i-love-voyager