In this historical photo from the U.S. space agency, the completely assembled Deep Space 1 (DS-1) technology demonstrator spacecraft is displayed. The DS-1 spacecraft incorporates a number of advanced technology concepts in its mission, but none so "high profile" as its Ion propulsion system.
The name itself evokes visions of Star Trek and science fiction fantasy, although the idea actually dates from the 1950s. However, unlike the "Warp Drive" propulsion system that zings the fictional starship Enterprise across the cosmos in minutes, the almost imperceptible thrust from the ion propulsion 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. Unlike the fireworks of most chemical rockets using solid or liquid fuels, the ion drive emits only an eerie blue glow as ionized (electrically charged) atoms of xenon are pushed out of the engine. Xenon is the same gas found in photo flash tubes and many lighthouse bulbs.
Deep Space 1 was launched in October 1998 as part of NASA's New Millennium Program, which is managed by JPL for NASA's Office of Space Science, Washington, DC. The California Institute of Technology in Pasadena manages JPL for NASA.
Each weekday, SPACE.com looks back at the history of spaceflight through photos (archive).