@inproceedings{oai:jaxa.repo.nii.ac.jp:00020391, author = {西野, 真木 and 藤本, 正樹 and 齋藤, 義文 and 横田, 勝一郎 and 浅村, 和史 and 田中, 孝明 and 綱川, 秀夫 and 渋谷, 秀敏 and 松島, 政貴 and 清水, 久芳 and Nishino, Masaki N. and Fujimoto, Masaki and Saito, Yoshifumi and Yokota, Shoichiro and Asamura, Kazushi and Tanaka, Takaaki and Tsunakawa, Hideo and Shibuya, Hidetoshi and Matsushima, Masaki and Shimizu, Hisayoshi}, book = {Proceedings of the ISAS lunar and planetary symposium}, month = {}, note = {The 41st ISAS Lunar and Planetary Symposium (August 6-8, 2008. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)), The moon spends most of its life staying in the solar wind (SW), where a quasi-vacuum region called the lunar wake is formed on the night side. The SW electrons with higher energy can come to the lunar night-side surface, while it has been thought that the SW ions are unlikely to approach the low altitude region on the night side because their thermal speed is much lower than the SW bulk speed. Here we show detection of SW ions sneaking into the anti-subsolar region at ca. 100 km altitude, using recent comprehensive measurement by a Japanese lunar orbiter SELENE (Kaguya). The sneaking of SW ions into the deepest lunar wake was accompanied by an enhancement of counter-streaming electrons along the SW magnetic field. A part of the ions detected in the anti-subsolar region came from the lunar surface, which means that the ions of solar wind origin reflected at the night-side surface. One possibility is that electron-rich wake environment strengthened the bipolar electric field at the wake boundary to let solar-wind ions approach the lunar night side, and the other scenario is that enhancement of ions in the wake let ambient electrons to come in., Physical characteristics: Original contains color illustrations, Number of authors: 12, 資料番号: AA0064291012}, pages = {52--55}, 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)}, title = {Plasma environment of the lunar wake observed by SELENE-MAP}, volume = {41}, year = {2009} }