ASER : ADVANCED SATELLITE ENGINEERING RESEARCH PROJECT
ASER project has been started in FY2003 under the contract from METI and NEDO. The purpose of the project is to develop key technologies for the next generation advanced satellite, utilizing the already developed technology through various preceding projects. There are 5 items to be developed, namely 1) High capacity thermal control system technology 2) Next generation electric propulsion system 3) Precise correction experiment of the onboard X'tal oscillator by ground based atomic clock 4) Large size composite structure manufacturing technology 5) High energy density Li-ION battery system The development results will be applied to Quasi Zenith Satellite System (QZSS), which is joint program of four government ministries, MPHPT, MEXT, METI, and MLIT for the significantly improvement of the accuracy of positioning for Japan by near zenith direction spacecrafts. MPHPT: The Ministry of Public Management, Home Affairs, Posts and Telecommunications, MEXT: Ministry of Education, Culture, Sports Science and Technology, METI: Ministry of Economy, Trade and Industry, MLIT: Ministry of Land, Infrastructure and Transport 1) High capacity thermal control system technology This is the development of large heat dissipation capability thermal control system. The system consists of 3 dimensional heat pipe network which enables heat transfer to and from any part of the satellite structure so that equipment heat can be dissipated at coldest surface of the satellite system of any particular point of time. Engineering model has been developed and tested.
2) Next generation electric propulsion system Hall thruster engine was selected as next generation electric thruster system since it can deliver relatively high thrust with high specific impulse. Thruster and power supply unit is under development. They will be subjected to life test to demonstrate reliable operation.
3) Precise correction experiment of the onboard X'tal oscillator by ground based atomic clock This system consists of on board crystal oscillator and ground based high accuracy atomic clock, linked by communication line with the satellite. The idea is to keep high clock accuracy by conventional crystal oscillator calibrated by ground based atomic clock. By employing this system, satellite clock with atomic accuracy can be attained with fraction of cost for on board crystal oscillator. Verification test using actual satellite link has been conducted.
4) Large size composite structure manufacturing technology Satellites are becoming more and more large in size these days. Up to now, large structure is manufactured as an assembly of many small piece parts, which hinders to lower the cost. This technology is to develop design and manufacturing of large scale composite structure in single piece. Satellite main structure with more than 4 meters in length has been manufactured in single piece utilizing this technology.
5) High energy density Li-ION battery system High energy density battery system with 175 AH Li-ION battery cells has been developed. In order to assure reliable operation and long operating life on orbit, the battery system has a) Cell over voltage protection circuit and b) Cell bypass switch in case of cell open circuit failure. The system went through qualification test.