When the Polar satellite was launched in February 1996, the plan was for a two-year mission to study the lights that form a ring around Earth's north and south magnetic poles. Polar exceeded expectations by a decade.

"We've gone well beyond our original plan and into our dreams," says John Sigwarth of the National Aeronautics and Space Administration's Goddard Space Flight Center in Greenbelt, Md.

"Polar ran out of fuel during its final maneuver in February," said Sigwarth. "But even after the fuel was exhausted, we continued to maneuver on the cold helium gas that was left in the tank," he said, likening that to "using the force of your breath as you breathe out to propel yourself backward" if you happen to be traveling through space like a satellite.

But now, he said, Polar has run out of breath.

Controllers turned off the satellite Monday, slightly ahead of a likely fatal encounter with the sun. From its current orientation, Polar will drift slowly, allowing the sun's energy to quickly overwhelm the satellite, Sigwarth said.