Electric propulsion systems have been identified as a key technology for transportation of DoD space assets. The AFRL IHPRPT Program is investing in the development of a dual-mode HET system. The DARPA FAST Program is considering high power HETs as part of their in-space technology demonstration of an all electric very high power space tug and GEO servicing vehicle. The unique HET design methodology to be implemented in this program could be applied across the thruster power spectrum giving it broad commercial applicability. Hall thruster systems in the 1-20 kW range are envisioned to assume both the orbit transfer and station keeping requirements for GEO communication satellites. The wide thrust-Isp capability of the proposed thruster is an essential feature for the dual mode requirement of high thrust for orbit raising and high Isp for station keeping. Commercial satellite manufacturers; SS/L, Boeing, Lockheed Martin and Orbital Sciences have all shown a strong interest in throttleable HET systems for their GEOSats. A study conducted by the SMD ISPT Project confirmed the significant potential of REP for space science, especially with recent advancements in enabling, high specific-power RPS technology (from 3 to over 8 We/kg). The study also concluded that REP would be ready for near-term NASA science missions if an electric propulsion thruster with the appropriate specific impulse throttle ability and propellant throughput capability could be developed. Following are the Trojan Asteroid, Jupiter Polar Orbiter with probes and Comet Surface Sample Return (Tempel 1) were three of the missions examined by this study. Other evaluations and assessments performed over the last decade have confirmed the benefits of REP for a variety of potential missions, including orbiters about Pluto, Neptune, and Uranus; rendezvous and Centaurs, Kuiper Belt Objects and primitive bodies in the outer Solar System; and extensive surveys of major asteroid groups. In general, REP offers the benefits of nuclear electric propulsion without the need for an excessively large spacecraft and power system.
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