NASA Retires Comet Hunter

NASA's comet-hunting Stardust spacecraft ended its 12-year career with a final experiment. The probe, which has traveled billions of miles since its launch in 1999, was ordered to burn the remaining fuel in its tanks, allowing engineers to calculate how much was left and improve fuel consumption models, Popular Science reports. "I think this is a fitting end for Stardust. It's going down swinging," a NASA engineer said.

With its fuel exhausted, the probe will be unable to keep its solar panels directed toward the sun and will shut down completely, remaining in orbit more than a million miles from Earth. It's "like saying goodbye to a friend," said a Stardust program manager for Lockheed Martin, who has worked on the probe since 1996. "It's been an amazing spacecraft. It's done everything we asked, it's done it perfectly." Stardust finished its main mission in 2006, and completed its final task, a fly-by of comet Tempel 1, last month. (More Stardust stories.)