The ion propulsion engine on Deep Space 1 has accumulated more operating time in space than any other propulsion system in the history of the space program.
Xenon is the same gas found in photo flash tubes and many lighthouse bulbs.
A similar engine powers the Deep Space 1 spacecraft. The almost imperceptible thrust from the system is equivalent to the pressure exerted by a sheet of paper held in the palm of your hand. The ion engine is very slow to pick up speed, but over the long haul it can deliver 10 times as much thrust per pound of fuel as more traditional rockets. Previous ion propulsion systems, like those found on some communications satellites, were not used as the main engines, but only to keep the satellites on track. Deep Space 1 is the first spacecraft to use this important technology as its primary means of propulsion.