Search

For a better global coverage of SLR (Satellite Laser Ranging) stations, We have formed an industry-government-academia research group in Japan and have designed and integrated a very minimum system for SLR. The basic concepts are small-size and low-cost in contrast to the majority of the existing SLR stations. As of early 2023, we have not tested actual ranging observations to SLR satellites yet, but we have finished testing its core components such as a laser, a timer and a telescope mount, and we are currently assembling these components and developing software. This project is linked with airbourne/satellite optical communications where high precision optical tracking is essential, and the deployment to the Antarctica is also under consideration., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

This presentation covers the 10 year history of GGOS Japan.As many as six Japanese national institutes have been operating large-size geodetic facilities with VLBI and/or SLR in Japan and also in Antarctica, and they had been involved in each geodetic service rather independently. In 2013, we initiated "GGOS Working Group" in Japan to enhance the communications among the Japanese institutes and global geodesists and also to encourage collaboration beyond each technique.GGOS Japan is basically a loose network, but it has a chair, a secretary, an outreach representative, working groups (currently active: Data DOI working group) and representatives of each geodetic technique (VLBI, SLR/LLR, GNSS, DORIS and gravimetry). We regularly host annual meetings and sometimes small meetings with focused issues. We have also involved in organising or supporting scientific sessions in domestic and international conferences.During the 10 years history, it was positioned as a GGOS Affiliate in 2017 and we renamed it as "GGOS Japan" in 2019. Basara Miyahara was elected as the GGOS President in 2019. GGOS Japan's webpages are being updated on the GGOS Website, and we have contributed to GGOS YouTube channels.We often set focused activities. We are currently working on the review of ITRF2020 from an operating point of view, and we are also working on a possible best location for a future GGOS Cores site in Japan. In the future we hope to collaborate with international communities, in particular with other GGOS Affiliates., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

A report from GGOS Japan, the first GGOS Affiliate, ranging from its 9-year history and the latest news.

Current satellite laser ranging (SLR) systems work at laser repetition rates of some 10 Hz up to about 10 kHz. However, using a laser repetition rate of 100 kHz offers several advantages: First, a laser with lower pulse energy can be used, while nevertheless the same amount of returns is received for a given target. Second, a poor single-shot precision (e.g. due to a long laser pulse) can be counteracted, as the statistical error decreases with the number of individual measurements. These two factors increase the number of options concerning the laser source, and may also help to make the system inherently eye-safe. Lastly, it may also help to gather data more quickly and thus increase the number of targets that can be tracked per system. A high repetition rate SLR system has been installed at the Uhlandshohe observatory in Stuttgart, Germany. Using an effective repetition rate of 100 kHz and a pulse energy of 50 µJ, various typical SLR targets could be ranged successfully, including LAGEOS and global Navigation System satellites at altitudes of around 20;000 km. A comparative orbit analysis, using data taken by other SLR stations at the same time, shows that a normal point scatter in the order of 1 cm is achieved despite the rather poor single-shot precision of about 60 cm. These results show an interesting potential especially for future low-cost SLR systems, that may utilize this technique to achieve competitive performance with small, low-energy lasers.

近年の新しいテクノロジにより、人工衛星の軌道をcmで測定することが可能になっている。そのデータ解析を行う軌道決定ソフトウェアにおいては、衛星に作用する加速度・地球の回転・地上局の動きなど、数多くの物理モデルを取り込む必要がある。一方で、精密軌道決定を通して、cmあるいはmmオーダーの新たな物理現象を検出することも可能である。, New technologies have made it possible to measure the satellite orbits at cm precision. Precise orbit determination software requires a number of physical models on the satellite acceleration, the rotation of the Earth, the site displacement, and so on. Reversely it can be used for detecting precise effects of cm or even sub-cm order., 資料番号: AA0063223003, レポート番号: JAXA-SP-06-015

資料番号: AA0063354022

重力ミッション衛星による地球重力場係数の決定においては,衛星位置の高精度な観測方式とともに,与えられた観測量から位置決定を行う精密軌道決定ソフトウェアが重要な役割を担う。情報通信研究機構(NICT)では,GPS受信機を搭載した低軌道衛星の軌道決定ソフトウェアの開発を行ってきた。GPS信号を用いた軌道決定では,ダイナミック法とキネマティック法の2種類の方式で軌道決定が可能である。GRACE衛星の軌道決定を行い,衛星レーザ測距及びK-Band測距観測値と比較したところ,ダイナミック法で数cm RMS程度での一致度を達成した。

高精度な軌道を得るために、レーザ反射鏡やGPS(Global Positioning System)受信機を搭載する低軌道衛星(代表的なものとして、LAGEOS(LAser GEOdynamics Satellite)・AJISAI(あじさい: EGS: Experimental Geodetic Satellite)・CHAMP(CHAllenging Minisatellite Payload)など)の数が増えてきている。計測精度は、数cmから、条件がよいときで1cm以下を達成している。この高い精度を活かすには、それに見合った精度で、衛星の運動力学や地球回転・局位置変動など、数多くの最新物理モデルを組み込む必要がある。NICT (National Institute of Information and Communications Technology)で開発中の軌道決定ソフトウェア'concerto'の紹介、これまでに得られた地球物理学的成果、さらに今後の展望について報告する。, A number of low earth orbiters carry a laser reflector array and/or a GPS (Global Positioning System) tracking system to obtain high precision orbit. The tracking precision is currently a few cm to sub cm. We have developed the analysis software 'concerto' whose physical models match or excel the measurement precision. The software is used to derive the motion of a satellite, the coordinates of tracking stations, Earth rotation, and other geophysical phenomena., 資料番号: AA0063480059

We propose a mission plan by means of a micro-satellite on a Low Earth Orbit (LEO) (300-1,000 km) with an advanced GPS (Global Positioning System) receiving system and a micro accelerometer on board. This LEO satellite can provide the following Earth observations: (1) time variations of low degrees Earth's gravity field coefficients; (2) fluctuations in atmospheric density in the thermosphere estimated from the atmospheric drags; (3) vertical structures of temperature, water vapor and electron density with GPS occultation technique; (4) the sea surface height and surface winds by receiving GPS reflection. The cost of this kind of small satellite is mush smaller than the ordinary earth observation satellites. Thus a large number of this kind of LEO satellites enables the low cost Earth's environments monitoring with high temporal and spatial resolutions in future., 資料番号: AA0063353011

通信総合研究所では、精密軌道解析ソフトウェアconcerto v4の開発を進めている。新しいver.4の開発の主眼は、解析できる入力データタイプの拡張と、さらなる軌道決定精度の向上である。前者については、これまでのSLRデータの他に、GPSの擬似測距および搬送波位相、測角、衛星搭載加速度計のデータを使用可能にする予定である。後者の精度向上のためには最新の物理モデルの利用が必要である。ver.4では、IERS Conventions 2003をベースとし、潮汐や衛星に作用する摂動に対しては、より精密なモデルを取り込んでいる。本稿では、新しいver.4の特徴について概説すると共に、CHAMPに搭載されたGPS受信機データを解析した結果についても述べる。, At Communications Research Laboratory, precise orbit determination software, 'concerto', has been developed and the new version 4 is now being tested. Major features of this new version are expansion to deal with multiple observation data types and improvement of orbit determination accuracy. Even though the old version of concerto can only solve Satellite Laser Ranging data, the new version will be possible to solve GPS code and carrier phase, angular observation, and accelerometer. Physical models included in version 4 are mostly based on IERS Conventions 2003. For the ocean tide and the perturbation acting on the satellite, more accurate models are implemented beyond the limit of IERS Conventions 2003. In this paper, the feature of concerto ver. 4 is overviewed and the result of the orbit determination with GPS precise orbit and CHAMP received data is described., 資料番号: AA0047899160

第14回宇宙科学シンポジウム (2014年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 14ｔh Space Science Symposium (January 9-10, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000058190, レポート番号: P2-158

第14回宇宙科学シンポジウム (2014年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 14ｔh Space Science Symposium (January 9-10, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000058191, レポート番号: P2-159

Skew of an image fiber, which has more than ten thousands of cores in a common cladding, was measured by a novel measurement method for the first time. This method can measure the time-of-flight difference between individual cores over the whole area of an image circle. The measurement result reveals that a test 100-m-long image fiber has skew of 5 ps/m, and the time-of-flight distributes randomly in the whole area of the image circle due to nonuniformity of the core dimension. It is also experimentally shown that the skew of an image fiber increases by bending. The theoretical analysis reveals that the bending-induced skew depends neither on the radius of curvature nor the shape of the curve but it depends only on the number of turns it is wound. The numerical calculation of skew by using typical parameters of image fibers shows that the winding have to be restricted to less than five turns to achieve a transmission speed of over 1 Gb/s/ch. Finally, we propose a twisted image fiber and an "8-shaped" bobbin to suppress the skew due to bending.

第4回極域科学シンポジウム横断セッション：[IP] 極域における多圏融合物理現象11月13日（水）国立極地研究所 ３階 ラウンジ

第13回宇宙科学シンポジウム (2013年1月8日-9日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 13th Space Science Symposium (January 8-9, 2013. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000063290, レポート番号: P5-028

第12回宇宙科学シンポジウム (2012年1月5日-6日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 12th Space Science Symposium (January 5-6, 2012. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 13名, 資料番号: SA6000064145, レポート番号: P4-048

第11回宇宙科学シンポジウム (2011年1月5日-7日. 宇宙航空研究開発機構宇宙科学研究所相模原キャンパス), 相模原市, 神奈川県, 11th Space Science Symposium (January 5-7, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 形態: CD-ROM1枚, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0065426112

第24回大気圏シンポジウム（2010年2月18日-19日. 宇宙航空研究開発機構宇宙科学研究本部（JAXA)(ISAS)）, 相模原市, 神奈川県, 24th Atmospheric Science Symposium (February 18-19, 2010. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 22名, 資料番号: SA6000073045, レポート番号: Ⅴ-22

第31回太陽系科学シンポジウム(2009年12月21-22日, 宇宙航空研究開発機構宇宙科学研究本部), The thirty-first Space Energy Symposium (December 21, 2009, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan), 形態: カラー図版あり, 形態: CD-ROM1枚, 著者人数: 11人, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0064738008

Skew of an image fiber, which has more than ten thousands of cores in a common cladding, was measured by a novel measurement method for the first time. This method can measure the time-of-flight difference between individual cores over the whole area of an image circle. The measurement results reveals that a test 100-m-long image fiber has skew of 5 ps/m, and the time-of-flight distributes randomly in the whole area of the image circle due to nonuniformity of the core dimension. It is also experimentally shown that the skew of an image fiber increases by bending. The theoretical analysis reveals that the bending-induced skew depends neither on the radius of curvature nor the shape of the curve but it depends only on the number of turns it is wound. The numerical calculation of skew by using typical parameters of image fibers shows that the winding have to be restricted to less than 12.5 turns to achieve a transmission speed of over 1 Gbps/ch. Lastly we propose twisted image fiber and a 8-shaped bobbin to suppress the skew due to bending.