{"created":"2023-06-20T13:20:23.782923+00:00","id":407,"links":{},"metadata":{"_buckets":{"deposit":"ec553c2f-c157-4f3d-8860-e7e0e16c80d5"},"_deposit":{"created_by":1,"id":"407","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"407"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00000407","sets":["2:427:11"]},"author_link":["8408","8406","8407"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"河野, 裕介"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"コウノ, ユウスケ"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2002-03-22"}]},"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":"　　The study on orbital motion and the interior structure of the Moon and planets is one of the methods to approach for the revolution as a dynamical system and the origin of the solar system. It is a powerful method to measure the gravity fields obtained by the orbital motion of a spacecraft in order to estimate the inner layer and the density structure of the Moon and the planets. Orbits or positions of a lunar or planetary spacecraft have mainly been determined by range and Doppler measurements. These measurements provide only one-dimensional information about the position along the line of sight. On the other hand, differential VLBI (Verv Long Baseline Interferometry) has the sensitivity of positioning in direction perpendicular to the line of sight, so that combining both range and Doppler measurements with differential VLBI enables us to measure three-dimensional position of a spacecraft. The research in this thesis is to develop a new three-dimensional positioning technique to determine the position and the motion of a spacecraft and to estimate the gravity fields and interior of the Moon or planets. In order to attain this purpose, a new differential VLBI, \"Multi-frequency VLBI\" is proposed, and the developments of its system and software for the estimation of phase delay are described. In addition to the VLBI method, effects caused by an antenna phase pattern and a spin on Doppler measurements are also described, and the correction method of this effect is proposed to improve the Doppler measurement accuracy.\n　　VLBI methods have been used for positioning of spacecrafts since 1960's. In these methods, carrier waves were transmitted from a spacecraft because of saving its transmitting power and obtaining hish SNR. Unfortunately, the phase delay of a carrier wave, however, has cycle ambiguities, therefore only phase delay rate has been mainly used so far. If plural carrier waves at different frequencies are transmitted from a spacecraft, the group delay among the plural carrier waves enables us to resolve the cycle ambiguity of the phase delay. There is one example which used two carrier waves. 6.5MHz apart transmitted from the spacecraft of the Venus. A group delay between the two frequencies was successfully determined without the ambiguity, in other words, bandwidth synthesis of only two frequencies was first conducted in this experiment. The accuracy of positioning reached 10 km for about 1 AU distance. In addition, the ionospheric effect could not be corrected because the two carrier waves were in the same frequency band.\n　　We propose a new VLBI method, \"Multi-frequency VLBI\". The system transmits three frequency signals in S-band and one signal in X-band. These frequencies are set to resolve the cycle ambiguity from a lot of group delays and to correct the ionospheric effect. In this system, the phase delay of RF signals at S and X-band can be estimated, so that the accuracy of positioning can be drastically improved by a factor of 1300 (8.4GHz/6.5 MHz). In order to realize this VLBI method, we developed a ground VLBI system, software to estimate phase delays and an irnterface with the software of gravity fields and orbits estimation. This software has the distinctive features as follows. It can estimate the current frequency from the predicted orbital motion and calculates the phase delay from the phase difference at the frequency. This performance allows us to utilize the oscillator for general use, such as a crystal oscillator, as a frequency reference onboard a spacecraft.\n　　We carried out VLBI experiments of NASA's spacecraft, Lunar Prospector (LP), as a preliminary test of the whole system. Unfortunately, LP transmitted only one frequency signal, so that we could not correct the phase variations with period longer than several tens seconds due to the ionosphere, troposphere, discrepancy of the lunar gravity model and so on. As a result of this experiment, residual phases from predicted ones are within ±2π, and the Root- Mean-Square (RMS) of the residual for the period of several seconds is about 4 degrees. The RMS residual for the several seconds, however, means that we can determine the position of LP within the accuracy of 1.5m around the Moon if we can correct the variations with long period by using the Multi-frequency VLBI. In the study of the Doppler measurements, we pointed out seven error sources that are the ionosphere, the troposphere, spin of the spacecraft, a phase pattern of an antenna, attitude of spacecraft, instability of a transponder and instability of a frequency standard. In particular, the effects caused by spin of a spacecraft and phase pattern of an antenna have not been discussed so far. We pointed out that the spin and the phase pattern of the antenna considerably affect the Doppler measurements and these effects must be removed from observed Doppler frequency data for a precise gravity determination. For this research, we analyzed a Doppler data of spin stabilized satellite, \"Nozomi\" and detected their effects of the spin and the phase pattern of the antenna for the first time. Furthermore, we developed a new method to remove this effect, and confirmed the validity of the method by applying the method to Doppler data of  \"Nozomi\" \n　　All the Multi-frequency VLBI and corrected Doppler frequency data can be combined as observables in the orbit and the lunar gravity estimation software of \"GEODYN-II\", and analyzed for three-dimensional positioning of a spacecraft. Because the VLBI system uses narrow bandwidth signals and the amount of the data is much less than those in conventional one, the system has a potential of real time VLBI through the INTERNET. This means that the system can be widely used in real time positioning of various spacecrafts, for instance a module landing on the Moon and the \"Nozomi\" in a transfer orbit to the Mars.","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586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":"2001"}]},"item_1_version_type_23":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_ab4af688f83e57aa","subitem_version_type":"AM"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"KONO, Yusuke","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586_要旨.pdf","filesize":[{"value":"338.5 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/407/files/甲586_要旨.pdf"},"version_id":"557b19a1-b254-4b84-9c8e-8f3a54ae7f57"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲586_本文.pdf","filesize":[{"value":"3.9 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/407/files/甲586_本文.pdf"},"version_id":"05e11ed2-2cb9-49ad-9f46-f57c0d8ae3d6"}]},"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":"Precise Three-dimensional Positioning of Spacecrafts by Multi-frequency VLBI and Doppler Measurementys","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Precise Three-dimensional Positioning of Spacecrafts by Multi-frequency VLBI and Doppler Measurementys"},{"subitem_title":"Precise Three-dimensional Positioning of Spacecrafts by Multi-frequency VLBI and Doppler Measurementys","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":"407","relation_version_is_last":true,"title":["Precise Three-dimensional Positioning of Spacecrafts by Multi-frequency VLBI and Doppler Measurementys"],"weko_creator_id":"1","weko_shared_id":1},"updated":"2023-06-20T14:55:05.903734+00:00"}