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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

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。

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