@inproceedings{oai:jaxa.repo.nii.ac.jp:00008117, author = {大登, 裕樹 and 山本, 真裕 and 江黒, 高志 and 高橋, 慶治 and 廣瀬, 和之 and 曽根, 理嗣 and 田島, 道夫 and Oto, Hiroki and Yamamoto, Masahiro and Eguro, Takashi and Takahashi, Keiji and Hirose, Kazuyuki and Sone, Yoshitsugu and Tajima, Michio}, book = {第23回宇宙エネルギーシンポジウム 平成15年度, The 23rd ISAS Space Energy Symposium March 9, 2004}, month = {Jun}, note = {Li ion batteries for space applications possess high discharge voltage, high specific energy, and lightweight properties, their research and development being conducted rapidly in recent years not only in the U.S. and France but also in Japan. Because of its weight reduction, the asteroid sample return mission spacecraft, HAYABUSA (MUSES-C before launch), which was launched in May 2003 and will bring back samples of the asteroid subsequently named ITOKAWA, 1998SF36, to the earth in June 2007, carried a Li ion battery with a specific energy of more than 85 Wh/kg. The battery consists of 11 prismatic cells with a rated capacity of 13.2 Ah, which are connected in series to supply power required to loads at a bus voltage of about 50 V during a discharge period. During a long mission period of about four and a half years, the battery is to be discharged only four times to launch the spacecraft, conduct its swing-by by means of the earth, make terminator observations to take images of the asteroid, and touch down on it to collect its samples. However, during the rest of the mission period except these events, a predetermined state of charge (SOC) must always be maintained because HAYABUSA is required to safely achieve the attitude control toward a safe hold mode for the sun acquisition in the event of sudden attitude anomalies. In addition, to remove an unbalanced SOC of each cell due to its capacity difference, a reset operation by which all the cells are charged up to a limit charge voltage of 4.1 V is to be conducted every four months. Therefore, a simulation model was developed on the ground using spare FM cells to predict SOC as precisely as possible before the reset operation. Already conducted was the reset operation two times successfully in orbit after the launch, evaluating a capacity test as well as the reset operation of the spare cells conducted on the ground at the same time. As a result, it has been confirmed that the capacity degradation of the onboard battery is as predicted according to the simulation model. It is planned to conduct the swing-by operation of the spacecraft by means of the earth in May 2004 and the first capacity test of the onboard battery in July 2004 and it is thought that the subsequent events can be overcome including achievement of a final safe hold mode to return to the earth., 資料番号: AA0047275001}, pages = {1--5}, publisher = {宇宙航空研究開発機構宇宙科学研究本部, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA/ISAS)}, title = {はやぶさ搭載バッテリーセルの運用経過}, year = {2004} }