Frédéric Marchandise

The PPS ® 1350-G Qualification Demonstration: 10500 hrs on the Ground and 5000 hrs in Flight

The PPS ® 1350-G is a thruste r d esigne d for North/South station keeping of satellites in the range 1 to 4 tons in Geostationary Earth Orbit (1.7 t to 6.5 t in GTO). The PPS®1350-G produces a nominal thrust of 88 10 -3 N for an electrical input power of 1,5 kW. On th e Smart-1 lunar mission (launch mass of 370 kg), a thruster of identical design has demonstrated almost 5000 hrs of ope rations in flight with a thrust of 70 10 -3 N for an available input power level of 1.2 kW. This pape r discusses the current qualification status of the PPS ® 1350-G. Th e qualification campaign starte d in 2002 with environmental tests. The camp aign then proceeded with life testing, and is still on going at th e Sn ecma test facilities. A first sequence of on/off cycles was completed, before a set of cold-cycle conditions in Russia, at OKB Fakel facilities. A second sequence of cold cycles were per formed at the beginning of 2006, to de monstrate the ab ility of the thruste r to operate in very cold conditions at the end of its operational life. These cold starts whe re performe d within a dedicated Snecma test facility at temperatures below -45°C. The thruster performance remaine d nominal after these tests. Since the end of these cold-start cycles, in the middle of 2006, life testing has resume d and is still on-going with the objective of de monstrating the capability required for the Alphabus platform. The objective in terms of on /off cycles was met in mid -Septe mber 2006, with over 7250 cycles; life testing is thus now proceeding with long firings, typically of 250 hours, in order to cover the total impulse needs for orbit toping. End of Dece mber 2006, over 10500 hrs of cumulate d run time and 3.39 10 6 N.s of total impulse have been demonstrate d by the Qualification Model (QM). Results show good thruster pe rformance, above the specified values. This paper will discuss the thruster performance in terms of eff iciency, thrust stability, thermal behavior and ion distribution (data measured along the life test). Thermal cartography of the thruster also provides information on the phenomena occurring during the e ngine startup transient. As already obse rved in flight as well as on most development tests, this thruster shows similar functional transition modes. Erosion of th e thruster and cathode is still occurring at a relatively slow pace, with special mention to the cathode exhibiting quite very little visible (external) erosion. Additionally, the diffe rent tests performe d on the PPS ® 1350-G thruster indicate an excellent availability and reliability. The diffe rent components reliability (cathode, anode block, xenon flow controller) will be discussed. With the use of Electric Propulsion, the issue

Electric Propulsion Thruster Assembly for Future Small Geostationary Comsats

A leader in Plasma Propulsion Systems, Snecma has developed a broad range of associated products and services, including Thruster Module Assemblies and the Smart-1 lunar probe Electric Propulsion Subsystem. Four flight units of the 1.5-kW PPS1350-G stationary plasma thruster are also nearing completion for Alphasat. New applications of the recurring hardware can now be considered. One such application would be to cover NorthSouth and East-West station-keeping maneuvers, momentum wheels off-loading as well as orbital maneuvers on board future, small geostationary communications satellites. This paper describes the application of the existing, flight proven electric propulsion hardware to this new class of missions.