The proposed 20 to 50 kW thruster system has many applications both as a stand-alone system and as part of a much larger (higher power) cluster. The thruster will be well suited for orbit raising and interplanetary transfers, supporting exploration and science missions. The demonstrated throttling ability is important for a singular thruster that might be called upon to propel a spacecraft from Earth to Mars or Venus. Mars orbits at 1.52 AU, which reduces the solar constant to 43% of the value at Earth. Venus orbits at 0.72 AU, which increases the solar constant to 190% of the value at Earth. As a result the output power of a nominal 10 kW array varies between 4.3 and 19.1 kW as a spacecraft travels between these planets. The ability to throttle efficiently is even more important for missions beyond Mars.
For DoD missions, including orbit raising for high power satellites and upper stages, the customer is the Air Force, via other defense contractors. A decade ago, the Air Force Research Laboratory (AFRL) initiated a program to cluster HETs as a means to reach the 100 kW to 150 kW power range desired for orbit transfer vehicles, space tugs, and re-supply vessels. Busek is working on the design an upper stage based upon the ESPA ring. A high power iodine Hall thruster system will would enable a high throughput (propellant mass >1200 kg), high delta-V orbit transfer stage based upon the ESPA ring. To carry more than ~450 kg of propellant, the system would have to be fitted with additional Xe propellant tanks that hang on the outside of the ring. With iodine, the ring could easily contain over 1200 kg of propellant. For truly commercial activities, such as GTO to GEO transfers, the customers are commercial satellite vendors and operators. Other potential customers are the emerging satellite servicing ventures such as MacDonald Dettwiler SIS and Vivisat.
More »