Since I just mentioned the possibility of solar sails being used for interstellar travel, it's worth pausing to remember the two most distant human-made objects, Voyager 1 and 2, both of which are beginning the transition into interstellar space. Both are still returning data. Reading a bit about the two craft on the mission page, NASA says that the mission team is down to 10 people.
After 30 years, that's dedication.
Image source: NASA/JPL