DENVER - NASA has ordered its comet-hunting Stardust probe to burn its remaining fuel, setting off a series of events that will shut down the spacecraft after a 12-year career.

Engineers gave the order Thursday from Lockheed Martin's Denver complex, where Stardust was built.

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Stardust will perform one last experiment by telling engineers how much fuel was left. That will tell them how accurate their fuel calculations were and help with the design of future probes.

Spacecraft don't carry fuel gauges because they don't work in zero gravity.

Stardust was launched in 1999. It completed its primary mission in 2004 by flying through a cloud of dust and gas enveloping the Wild 2 comet and capturing samples. Those were sent to Earth for study via a parachute-equipped canister.