In the past 20 years MBBDASA has developed, qualified and delivered to several customers two types of satellite propulsion thrusters (10 Nand 400 N). These thrusters have been successfully brought into operation and are working in 12 satellites (including GALILEO spaceprobe) without any difficulties. After this remarkable break-through in the satellite business (mainly telecommunication satellites) we started to concentrate internal efforts on the imorovement of the aoulied technolo- .I gies.A second generation of thrusters was decided in order to improve the performenace and the operation range for future application.In the frame of this work the family of the bi-propellant thrusters was enlarged. For high accuracy attitude control a 4 N thruster was developed and for more efficient apogee injection an increase of the 400 N performance level is in preparation. , ; he presentation will demonstrate the history of the 1st generation thrusters (swirl atomising injection system and three types of cooling: film-regenerative-radiative) and the excellent in-orbit operation. A second part will cover the latest status of development/qualification/application of the 2nd generation thrusters (swirl atomising injection system and two types of cooling: film-radiative).Details on the material selection, on the joining technology for the different materials and on the achieved performances will be presented. The development of the 2nd generation thrusters started with the 4 N thruster in the mid-80's with principle operation tests. After a few years this line was corrected to the 10 N thrusters which was the most demanding thrust level to be improved. Fig. 5 shows a foto of the 10 N Pt/Rh thruster in the qualified version. This thruster will be applied in the EUROPEAN scientific program CLUSTER for orbit and attitude correction. Parallel to the 10 N thruster the development of a 4 N thruster (Fig. 22) was restarted and shall be completed by a qualification in 1992/93. A third thrust level (400 N) is at the moment in preparation and shall complete the new enlarged 2nd generation family in 1993/1994. Finally the existing and intended projects applying the second genration thrusters will be discussed showing the advantages of using one single type high performing bi-propellant thructer technology.

No abstract

On the basis of more than 200 successfully operating bi-propellant engines of the fust generation in orbit DASA is now in qualification process on ground of the second generation This new family of satellitelspaceprobe and orbit insertiodcorrection engines offers several advantages like performance improvement, pulse mode improvement and enlarged operation range. Three different thrust levels are represented by this new family: -4 N thruster for attitude control with main interest on high accuracy minimum impulse bit 10 N thruster for orbit correction and/or insertion support with concentration on high specific performance and very long burning time for injection backup capability 400 N engine for orbit injection and/or correction with rather large thrust level hut low enough not to create too strong constraints to the spacecraft. The presentation will mainly concentrate on the qualification status of these new engines. This qualification demonstration will cover the whole hot f r h g specrmm as well as the environmental testing. This new generation differs from the first one in principle by two main characteristics:replacement of normal standard material by high temperature resistant material (without the need of surface coaelimination of regenerative cooling in the hottest area (nozzle throat).--ting)AU the other principles like swirl atomizing injector, film cooled combustion chamber, radiative cooled expansion nozzle as well as monostable thruster valve will remain nearly unchan-The 10 N thruster was the first item submitted to the introduction of this new generation of engines.During qualification under extreme conditions the regeneratively cooled 10 N thrusters showed limits in operation reaching high mixture ratio at high mass flow with the risk to reach thermal instability endangering the thruster life.The new generation allowed to increase the operation range into higher areas of mixture ratio and mass as well as down to lower values. At the same time the specific impulse and the minimum impulse hit could be improved as well The presentation will show the qualification test results with respect to long burning time (more than 50 hours), high number of duty cycles (more than 700.000 pulses) and comfonable resistance against environmental vibration loads.ged Following high accuracy requirements for attitude fine pointing DASA decided to decrease the thrust level for its bi-propellant thrusters as far as possible. This attempt ended up in the development of a 4 N thruster. For this thruster the presentation will also demonstrate the feasibility for long burning time (more than 40 hours), high number of duty cycles (more than 750.000 pulses), exeemely low minimum impulse bits (C 13 mNs) with very high reproduceability, high specific impulse during pulse mode operation and also comfortable resistance against environmental loads.The third member of the new bi-propellant thruster family of DASA is the 400 N engine mainly applied for apogee injection manoeuvres. Due to the much higher through-put of propellants ...

All artificial satellites surrounding the earth request a propulsion system in order to perform the necessary orbit and attitude correction manoeuvres. These propulsion systems are nearly all based on liquid systems (either mono-or bipropellant), sometimes in combination with solid and/or gas systems. Today most of the satellites use bipropellant systems for injection as well as correction manoeuvres. Especially in Europe all telecomuiunication satellites use bi-propellant systems and DASA also suceeded to receive a contract for the scientific CLUSTER program using its bi-propellant thrusters. The main reason for this decision was the fact that DASA was preparing a second generation of low thrust engines (10 N) offering slightly increased performance. 111 the meantime this new 10 N thruster was successfully qualified for CLUSTER and in addition also for telecommunication satellites.Furtheron DASA developed a 4 N bipropellant thruster for attitude control which has already passed pre-qualification tests and will be submitted to formal qualification testing early 1993. This Daner summarizes the aualification test results of the 10

No abstract