Ulysses, a solar-orbiting spacecraft launched in 1990, was finally retired a few weeks ago by NASA and the European Space Agency after nearly two decades of operation. In a huge elliptical loop, Ulysses swung by Earth, orbiting all the way out beyond the orbit of Jupiter, then back over the sun's poles to characterize our star's effects on its environs, only to begin another lap every six years or so.

Although the time and distance logged by Ulysses are significant, there are many older spacecraft that continue to function today. Some are just hanging on, puttering away in deep space awaiting human contact that may never come, whereas some are in daily use as communication links, monitors of Earth's activity or probes of astronomical processes.

Hailing from the 1960s to the early 1990s, here are 10 spacecraft and satellites—by no means an exhaustive list—that refuse to give up the ghost decades after deployment.