{"created":"2023-06-20T14:36:04.189774+00:00","id":2372,"links":{},"metadata":{"_buckets":{"deposit":"d8e3248b-df3c-498b-8f87-4f19d82de0ba"},"_deposit":{"created_by":1,"id":"2372","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"2372"},"status":"published"},"_oai":{"id":"oai:jaxa.repo.nii.ac.jp:00002372","sets":["1887:1893","9:10:309:351"]},"author_link":["5749","5748","5747","5745","5744","5746","5743","5740","5741","5742"],"item_3_alternative_title_2":{"attribute_name":"その他のタイトル（英）","attribute_value_mlt":[{"subitem_alternative_title":"Development of lightning and airglow camera onboard Venus Climate Orbiter"}]},"item_3_biblio_info_10":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2005-03-31","bibliographicIssueDateType":"Issued"},"bibliographicVolumeNumber":"JAXA-RR-04-016","bibliographic_titles":[{"bibliographic_title":"宇宙航空研究開発機構研究開発報告"},{"bibliographic_title":"JAXA Research and Development Report","bibliographic_titleLang":"en"}]}]},"item_3_description_16":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"現在、金星大気超回転の解明を主目的とした金星気象衛星(VCO: Venus Climate Orbiter)を打ち上げるPlanet-Cミッションが宇宙航空研究開発機構／宇宙科学研究本部を中心として進行中である。VCOに搭載する雷・大気光カメラ(LAC: Lightning and Airglow Camera)の開発を行っている。LACは金星夜面における雷放電発光・大気光を2次元で高速イメージングする観測器である。雷放電観測では、まずこの現象の存在の決定的な証拠を得て、長年の論争を収束させることを目標とする。大気光観測では、発光強度の緯度・経度分布から金星超高層大気の運動を継続的にモニターし、さらに波状構造をイメージングすることで、金星下部熱圏と下層大気の力学的結合過程の解明、金星熱圏大気大循環メカニズムの理解の進展が期待される。さらに近年、地上望遠鏡で発見された558nm(OI)の連続観測も実施し、その発光強度分布や時間変動を捉え、オーロラとも解釈できるこの発光現象の解明を目指す。LACのセンサーとしては、高感度を有し、かつ高速サンプリングが可能なものが要求される。また本観測器は、雷放電発光観測用に波長777nm(OI)の干渉フィルタを採用し、50kHzプレトリガーサンプリングでデータを取得する。一方、大気光観測時には波長551nm(O2 Herzberg 2)、558nm(OI)で連続サンプリングを行い、積分時間10secで1枚の画像を作成する。VCOは金星低緯度を周回する長楕円軌道をとるが、LACはこのうち近金点(高度300km)付近から金星より3Rv離れた地点までの高度範囲で運用する。その際、雷放電発光観測に関しては距離3Rvの地点から地球の平均的発光強度のものを、1,000kmの高度からはその1/l00レベルのものまでを検出することを目標とする。一方、大気光に関しては発光強度100Rのものを、SN比=10を確保して検出することを目標とする。上記の性能を達成するため、第1に、LACのセンサーとして光電子増倍管(PMT: Photo Multiplier Tube)とアバランシェ・フォトダイオード(APD: Avalanche Photo Diode)の2つを検討した。いずれも8×8の2次元配列素子である。絶対感度校正実験から得られた出力電流値と、暗電流測定試験から得られた暗電流値から、本観測器で100 Rayleighの光源を観測した場合の暗電流統計揺らぎによるSN比が10以上であることを確認した。第2に、金星夜面観測の際に視野内に混入することが予想される迷光(太陽直達光、金星昼面光)の量を見積もり、迷光減衰要求量11桁を達成する高い遮光技術を有する光学系の設計・開発を行った。衛星側面に設置し片側を宇宙空間に暴露させ、対物側に4枚の遮光板(vane)と1段バッフルを取り付けた光学系を設計した。その結果、衛星突起物がベーン陰影内にある場合、その迷光量はカメラ部の1段バッフルから検出器間の遮光対策で十分減衰可能な量であることを定量的に示した。第3に、高速サンプリング時におけるデータ取得方法の考案・検討を実施した。忘却係数という概念を用いてトリガーサンプリング方法を考案し、地上フォトメータで捉えられた地球雷放電発光の波形で試験した結果、ノイズと分離して信号を検出することに成功した。本研究成果により、LAC開発に必要不可欠な基礎技術の活用に見通しを立てることができた。","subitem_description_type":"Abstract"}]},"item_3_description_17":{"attribute_name":"抄録（英）","attribute_value_mlt":[{"subitem_description":"A Lightning and Airglow Camera (LAC) onboard the Venus Climate Orbiter (VCO), the Japanese Venus mission Planet-C, is being developed. The LAC is a high-speed imaging sensor and measures lightning flashes and airglow emissions on the Venus nightside disk. One of the major targets of LAC is to settle controversy on the existence of the lightning of Venus. Further, the LAC observations provide information for the charge separation mechanism, physics of sulfuric acid clouds, mesoscale planetary meteorology and impacts on atmospheric chemical processes. The regions of intense airglow emission normally distributed on the morning side of the antisolar point, which reflects that the super-rotation of the upper atmosphere modifies subsolar-to-antisolar circulation cell. So continuous observations of nightglow provide information on the global circulation in the Venus lower thermosphere. Furthermore, a plan is being made to measure the 558 nm (OI) emission which was recently discovered by a ground-based telescope, but its origin is mysterious. Both high-sensitivity and high-speed samplings are performances required for the detector of LAC. And it needs to have 8 by 8 matrix. Interference filters are used for selecting a wavelength of 777 nm (OI) for lightning flash measurement and wavelength of 551 nm (O2 Herzberg 2) and 558 nm (OI) for nightglow measurement. Individual lightning flash events are recorded with a 50 kHz pre-trigger sampling. The goal of LAC is to detect lightning events with the optical intensity of 1/100 of typical lightning events on the Earth from 1,000 km altitude and to measure 100 Rayleigh airglow with signal to noise ratio (S/N) more than 10. To realize this performance, first, Photo-Multiplier Tube (PMT) and Avalanche Photo-Diode (APD) were selected and examined as a candidate of the detector of LAC. An absolute calibration of the optical sensitivity and a measurement of thermal characteristics of dark current were performed. These results shows both PMT and APD have an ability to satisfy S/N more than 10 when LAC observes 100 Rayleigh airglow emission using them. But the problem of PMT is low quantum efficiency, while the one of APD is thermal instability of dark current. So it is concluded that PMT is suitable to detect airglow emission and APD is useful to observe lightning flash. Second, a high-contrast optics of which reduces stray-light by an order of 10(exp -11) was designed and developed. When the LAC observes the Venus nightside disk, the light from the sun and Venus dayside disk are serious contaminations. To reduce them, LAC is installed on the surface of the satellite and four vanes are set on the objective side of the camera. However, the light scattered by the surface of the satellite and the objects put on the surface, such as antenna, may seriously reduce the signal to noise ratio. The intensity of these scattered light is evaluated using detailed models to solve this problem. The results indicate that the amount of scattered light can be sufficiently reduced by a baffle under the condition that the projecting objects put at the backward of the baffle aperture. Third, data acquisition for high-speed pre-trigger sampling was designed. A very simple trigger logic was devised using oblivion coefficient and tested for terrestrial lightning flashes data obtained with a photometer on the ground. It is confirmed that this logic is quite useful to distinguish between the lightning signal and other noises.","subitem_description_type":"Other"}]},"item_3_description_32":{"attribute_name":"資料番号","attribute_value_mlt":[{"subitem_description":"資料番号: AA0048513000","subitem_description_type":"Other"}]},"item_3_description_33":{"attribute_name":"レポート番号","attribute_value_mlt":[{"subitem_description":"レポート番号: JAXA-RR-04-016","subitem_description_type":"Other"}]},"item_3_publisher_8":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"宇宙航空研究開発機構"}]},"item_3_publisher_9":{"attribute_name":"出版者（英）","attribute_value_mlt":[{"subitem_publisher":"Japan Aerospace Exploration Agency (JAXA)"}]},"item_3_source_id_21":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"1349-1113","subitem_source_identifier_type":"ISSN"}]},"item_3_source_id_24":{"attribute_name":"書誌レコードID","attribute_value_mlt":[{"subitem_source_identifier":"AA1192675X","subitem_source_identifier_type":"NCID"}]},"item_3_text_6":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"東北大学 大学院理学研究科"},{"subitem_text_value":"東北大学 大学院理学研究科"},{"subitem_text_value":"東北大学 大学院理学研究科"},{"subitem_text_value":"国立極地研究所"},{"subitem_text_value":"大阪府立大学 大学院工学研究科"}]},"item_3_text_7":{"attribute_name":"著者所属（英）","attribute_value_mlt":[{"subitem_text_language":"en","subitem_text_value":"Tohoku University Graduate School of Science"},{"subitem_text_language":"en","subitem_text_value":"Tohoku University Graduate School of Science"},{"subitem_text_language":"en","subitem_text_value":"Tohoku University Graduate School of Science"},{"subitem_text_language":"en","subitem_text_value":"National Institute of Polar Research"},{"subitem_text_language":"en","subitem_text_value":"Osaka Prefecture University Graduate School of Engineering"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"吉田, 純"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"高橋, 幸弘"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"福西, 浩"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"堤, 雅基"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"牛尾, 知雄"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"Yoshida, Jun","creatorNameLang":"en"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"Takahashi, Yukihiro","creatorNameLang":"en"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"Fukunishi, Hiroshi","creatorNameLang":"en"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"Tsutsumi, Masaki","creatorNameLang":"en"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"Ushio, Tomoo","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2020-01-15"}],"displaytype":"detail","filename":"48513000.pdf","filesize":[{"value":"7.3 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"48513000.pdf","url":"https://jaxa.repo.nii.ac.jp/record/2372/files/48513000.pdf"},"version_id":"d4c8b2f4-c964-4c0d-8129-4648abd4f937"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"惑星環境","subitem_subject_scheme":"Other"},{"subitem_subject":"金星","subitem_subject_scheme":"Other"},{"subitem_subject":"宇宙探査","subitem_subject_scheme":"Other"},{"subitem_subject":"金星気象衛星","subitem_subject_scheme":"Other"},{"subitem_subject":"雷","subitem_subject_scheme":"Other"},{"subitem_subject":"大気光","subitem_subject_scheme":"Other"},{"subitem_subject":"惑星大気","subitem_subject_scheme":"Other"},{"subitem_subject":"放電","subitem_subject_scheme":"Other"},{"subitem_subject":"planetary environment","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"Venus","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"space exploration","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"Venus Climate Orbiter","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"lightning","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"airglow","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"planetary atmosphere","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"electric discharge","subitem_subject_language":"en","subitem_subject_scheme":"Other"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"technical report","resourceuri":"http://purl.org/coar/resource_type/c_18gh"}]},"item_title":"Venus Climate Orbiter搭載　雷・大気光カメラの開発","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Venus Climate Orbiter搭載　雷・大気光カメラの開発"}]},"item_type_id":"3","owner":"1","path":["351","1893"],"pubdate":{"attribute_name":"公開日","attribute_value":"2015-03-26"},"publish_date":"2015-03-26","publish_status":"0","recid":"2372","relation_version_is_last":true,"title":["Venus Climate Orbiter搭載　雷・大気光カメラの開発"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-06-21T09:23:45.953203+00:00"}