The NASA Solar Electric Power Technology Application Readiness (NSTAR) 30-centimeter system, consisting of an ion thruster, power processor, and digital control and interface units, was designed specifically to support NASA's future requirements. It is being validated by the New Millennium Deep Space 1 project.

Unlike its commercial satellite counterpart that uses a xenon ion propulsion system, XIPS (pronounced "zips"), for north-south stationkeeping and for orbit raising, the NSTAR system will be the primary propulsion system for the Deep Space 1 spacecraft.

The Deep Space 1 spacecraft may be the first of several to use the NSTAR system. Under the $8.1 million contract that was awarded by NASA to Hughes Electron Dynamics Division in 1995, two flight thrusters, and associated power processor and digital control and interface units, were produced.

The advantage of ion propulsion is efficiency. Ion propulsion is 10 times more efficient than chemical thrusters. This translates into a reduction of propellant mass of up to 90%. For commercial communications satellites, the reduced propellant mass creates an option to reduce launch cost, increase payload, or increase satellite lifetime, or any combination of the above.

For Deep Space 1, the improved propellant efficiency of the NSTAR system results in a lighter spacecraft that will reach its destination in half the time. Deep Space 1 is currently scheduled to reach the near-Earth asteroid 1992 KD in July 1999.

By Oct. 1999, Deep Space 1 will have completed its primary mission and will be on a trajectory that could result in an encounter with Comets Wilson-Harrington and Borelly in 2001.

"XIPS is the result of more than 40 years or research by Hughes and NASA. The NSTAR 30-centimeter system was designed to meet very specific operational parameters," said Tim Fong, manager of Hughes Electron Dynamics Division.

"The NSTAR ion propulsion system on Deep Space 1 requires operation over a wide range of thrust and input power, since the solar power available drops significantly as the spacecraft goes further away from the sun. This NSTAR system is remotely programmable, allowing NASA to adjust its thrust to meet these changing conditions over the life of the mission."

In addition to the 30-centimeter NSTAR system designed for NASA, Hughes Electron Dynamics Division also produces two commercial XIPS systems: a 13-centimeter unit that is an option on the HS 601 spacecraft built by Hughes Space and Communications Co., and a 25-centimeter version that will debut on Hughes' first HS 702 in early 1999.

Hughes Electron Dynamics Division built the first commercial XIPS system, which was launched Aug. 28, 1997, on PAS-5, an HS 601HP satellite for PanAmSat Corp.