{"created":"2023-06-20T13:20:24.372646+00:00","id":418,"links":{},"metadata":{"_buckets":{"deposit":"7922f1e3-ce27-4d64-8c9e-1d5d3bae3fd9"},"_deposit":{"created_by":1,"id":"418","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"418"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00000418","sets":["2:427:11"]},"author_link":["8440","8441","8442"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"菅野, 貴之"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"スガノ, タカユキ"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2004-03-24"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（理学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":"　Gravity field studies have been playing an important role in investigating physical properties, origin, and evolution of terrestrial planets and satellites. Information on the Moon's gravity field has been provided by radio tracking data of lunar satellites. The study began in 1966 with the satellite Luna 10, followed by Lunar Orbiters I-V and Apollo 15, 16 sub-satellites in 1960's. Several gravity field models, based on a spherical harmonic expansion, were produced from the analysis of the tracking data. The accuracy of the gravity model was dramatically improved by the recent two lunar satellites, the Clementine and the Lunar Prospector in 1990's. \n　The Lunar Prospector was launched on January 7, 1998. After finishing the 1 year nominal mission at the 100km×100km polar orbit, 6months long extended mission was carried at the average height of 30km. The highest-resolution gravity model called LP165P was produced from the low-altitude extended mission tracking data. Lunar gravity studies have a difficulty peculiar to the Moon. i.e., direct tracking data are available only at the lunar nearside because of its synchronized spin and orbital motion. The lack of farside data has been hindering us from making high resolution gravity anomaly map. In fact, the LP165P gravity anomaly map, obtained imposing artificial constraints to stabilize the estimation of coefficients using only nearside tracking data, has many spurious linear features; the model is reliable only up to 110th degree/order at the farside. \n　On the other hand, line-of-sight acceleration of the Lunar Prospector satellite during its extended low-altitude mission are available at the Planetary Data System Geosciences Note web site. Direct inversion of such data into surface mass distribution has two merits,i.e., high resolution can be attained without relying on artificial constraints, and short computation time by estimating regional parameter sets stepwise. We downloaded the LOS data product and used them for analysis of lunar gravity field. We assume that masses giving rise to the gravity anomaly are condensed in a thin layer on the lunar reference surface. First the surface is divided into large blocks as large as 500-600km, then they are subdivided into small brocks of about 25km in size. Assuming gravity anomaly at satellite positions are sum of the gravity fields of these small brocks, we estimated their masses using the least-squares method. The validity of the method is also confirmed using synthesized data. We moved the position of large block throughout the nearside to get the free-air gravity anomalies over the entire nearside. Resolution of the obtained anomaly map is equivalent to conventional model using spherical harmonics complete to 225th degree/order. Our model has much less spurious signatures than past models. \n　To take advantage of the high resolution of the obtained map, we calculated mass deficits associated with medium-sized craters (mostly formed in 4.6-3.9 Gy before present, 80-300km in diameter). They are found to be nearly proportional to 2.6 power of crater diameter. This is somewhat smaller than those inferred from topographies, which may be due to the existence of higher density impact melt sheet on the crater floor. \n　Next we performed terrain corrections for the raw LOS acceleration data using the lunar topography grid data obtained by the Clementine laser altimetry. By conducting same inversion for the corrected data, we obtained Bouguer gravity anomaly map that mainly reflects the topography of Moho. Mass deficits are not seen in the Bouguer anomaly map for the medium-sized craters, suggesting that isotatic compensation did not occur for craters up to 300km in diameter. This indicates the lunar lithosphere was already as thick as 100km at the time of these crater formations, which will serve as an important constraint to discus the initial thermal status and the cooling history of the Moon since its genesis.","subitem_description_type":"Other"}]},"item_1_description_18":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第752号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"数物科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"09 天文科学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2003"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"SUGANO, Takayuki","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":"2016-02-17"}],"displaytype":"simple","filename":"甲752_要旨.pdf","filesize":[{"value":"376.3 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨 / Abstract, Screening Result","url":"https://ir.soken.ac.jp/record/418/files/甲752_要旨.pdf"},"version_id":"e778fa61-ddb8-46c9-9b75-5aee5d725a59"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"LUNAR INTERIOR STUDIES USING THE LUNAR PROSPECTOR LINE-OF-SIGHT ACCELERATION DATA","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"LUNAR INTERIOR STUDIES USING THE LUNAR PROSPECTOR LINE-OF-SIGHT ACCELERATION DATA"},{"subitem_title":"LUNAR INTERIOR STUDIES USING THE LUNAR PROSPECTOR LINE-OF-SIGHT ACCELERATION DATA","subitem_title_language":"en"}]},"item_type_id":"1","owner":"1","path":["11"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-02-22"},"publish_date":"2010-02-22","publish_status":"0","recid":"418","relation_version_is_last":true,"title":["LUNAR INTERIOR STUDIES USING THE LUNAR PROSPECTOR LINE-OF-SIGHT ACCELERATION DATA"],"weko_creator_id":"1","weko_shared_id":1},"updated":"2023-06-20T14:54:51.104970+00:00"}