In the Payload Hazardous Servicing Facility, workers guide a protective canister as it is lowered over the Stardust spacecraft. Once it is enclosed, Stardust will be moved to Launch Pad 17-A, Cape Canaveral Air Station, for launch preparations. Stardust is targeted for liftoff on Feb. 6 aboard a Boeing Delta II rocket for a close encounter with the comet Wild 2 in January 2004. Using a silicon-based substance called aerogel, Stardust will capture comet particles flying off the nucleus of the comet. The spacecraft also will bring back samples of interstellar dust. These materials consist of ancient pre-solar interstellar grains and other remnants left over from the formation of the solar system. Scientists expect their analysis to provide important insights into the evolution of the sun and planets and possibly into the origin of life itself. The collected samples will return to Earth in a sample return capsule to be jettisoned as Stardust swings by Earth in January 2006