In 1997, the International Sun-Earth Explorer 3 (ISEE-3), its extended mission completed, was left to its own devices in space. No one even tried to talk to the venerable probe (launched in 1978), which had studied cosmic rays, comets, and solar phenomena. A private group, the ISEE-3 Reboot Project, came to its rescue. A crowdfunded effort, the Project reached a Space Act agreement with NASA allowing them to try to contact the probe and set it to yet another mission. Using the Arecibo Observatory in Puerto Rico, project engineers on 29 May made contact and got a response from the "dead" spacecraft. With $160,000 raised from Kickstarter, the group has plans to fire the ancient engine and send ISEE-3 to ES-1, the Earth-Sun Lagrange Point 1, nearly a million miles from Earth, and get the instruments going again.
This effort is groundbreaking in so many ways. Reviving a spacecraft launched when Jimmy Carter was President. A citizen group taking over and running a NASA probe. This really is a voyage into new frontiers. (I contributed, by the way).