DENVER, Colorado - NASA ordered its comet-hunting Stardust probe to burn its remaining fuel on Thursday, setting off a sequence that shut down the spacecraft after a 12-year career.

Stardust had finished its main mission in 2006, sending particles from a comet to Earth. It took on another job last month, photographing a crater on an asteroid.

It accomplished one last experiment on Thursday, firing its thrusters until its last hydrazine fuel was gone. The length of that burn, a little under 2 1/2 minutes, will tell engineers exactly how much fuel was left so they can see how accurate their calculations were.