Hughes' Ion Engine Serving as Primary Propulsion to NASA's Deep Space 1
In 1995, Hughes Electron Dynamics, today known as Boeing Electron Dynamic Devices, Inc., located in Torrance, Calif., was awarded a $9.2 million contract to design and manufacture the NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) 30-centimeter system for validation on the New Millennium Deep Space 1 project. This would be the first time an ion engine would be used as the primary method of propulsion in a deep space mission. The system consists of an ion thruster, power processor, and digital control and interface units.
Deep Space 1 was launched on Oct. 24, 1998 from the Cape Canaveral Air Station, the first mission in NASA's New Millennium Program. The purpose of the New Millennium Program is to test and validate new technologies in a series of deep space and Earth-orbiting missions. This is the first deep space NASA mission to focus on technology, rather than science.
As one of the 12 new technologies being tested on Deep Space 1, the ion engine performs the critical role of spacecraft propulsion. It is the primary method of propulsion for the 8-1/2-foot, 1,000-pound spacecraft, and its use is preparing it for possible inclusion in future NASA space science missions.
Still on its planned 11-month technology validation mission, as of the end of February 1999, the Deep Space 1 spacecraft has traveled more than 28 million miles from Earth.
An ion engine relies on electrically charged atoms, or ions, to generate thrust. Xenon, an inert, noncombustible gas, is electrically charged and the ions are accelerated to a speed of about 62,900 miles per hour (30 kilometers per second). The ions are then emitted as exhaust from the thruster, creating a force, which propels the spacecraft in the opposite direction.
The primary advantage of electric propulsion is efficiency. An ion engine is 10 times more efficient than its alternative, a chemical propulsion system. With xenon, it is possible to reduce propellant mass onboard a spacecraft by up to 90 percent. The advantages of having less onboard propellant include a lighter spacecraft, and, since launch costs are set based on spacecraft weight, reduced launch cost.
Unlike its chemical counterpart, the ion engine produces a gentle thrust, but for a very long duration. The Deep Space 1 spacecraft carried about 81.5 kilograms of xenon propellant, which will provide about 20 months of continuous thrusting, more than enough to propel Deep Space 1 throughout its entire mission. The 30-centimeter ion thruster on Deep Space 1 will eventually change the spacecraft's speed by 4.5 kilometers per second, the equivalent of 10,000 miles per hour.
Hughes and NASA began investigating the use of xenon as a propellant alternative back in the early 1960s. Other materials, such as cesium and mercury, were also investigated, but xenon was preferred because it would generate the greatest thrust and, as an inert gas, would not be hazardous to handle and process.
The NSTAR engine was designed for operation in deep space. Prolonged periods of operation in low levels of sunlight required a unique design for deep space missions. The NSTAR engine is remotely programmable from the ground, enabling ground stations to adjust the thruster's operation as needed. The spacecraft's on-board autonomous software can also adjust the operation of the thruster.
Boeing Electron Dynamic Designs also produces a commercial xenon ion propulsion system, XIPS, for use on Boeing 601HP and Boeing 702 spacecraft in geosynchronous orbit. The first satellite to fly with an onboard XIPS system was PAS-5, which was launched in August 1997.
Boeing Electron Dynamic Designs is a world leader in the design and manufacture of microwave, traveling wavetube amplifiers, and ion thrusters for commercial and military applications.
Deep Space 1 Ion Drive Engine
