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Subsurface structures of the Moon reflect the history of past volcanic activity and thermal evolution, and is important to understand the formation and evolution of the Moon. The Lunar Radar Sounder (LRS) has detected reflected echoes from the regolith layers formed between different subsurface lava units in many lunar Maria. From them, the lava eruption volume and eruption rate can be estimated. Both types of knowledge areimportant for elucidating lunar volcanic activity. Nevertheless, most subsurface analyses by LRS are limited to large-scale layered structures, and the subsurface structures below small-scale volcanic terrains which have been discovered in recent high-resolution camera images have not been detected using LRS. Because off-nadir surface scattering echoes are superimposed on nadir echoes from small-scale subsurface structure in LRS observation data, it is difficult for us to distinguish between the two. For this study, after we evaluated the surface scattering effects on the moon by surface scattering simulation, we compared them with LRS observation data to assess the detectability of small-scale subsurface echoes. Results for one ground track of LRS show the possibility of identifying small-scale subsurface echoes. The analytical method described herein can be applied to the lunar global area and could reveal the distribution of small-scale subsurface echoes and the subsurface structure on the global Moon in the future. These data are expected to contribute to a more detailed understanding of the volcanic history of the Moon., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA2230011000, レポート番号: JAXA-RR-22-005E

Using the plasma instruments (LEPi, LEPe, MEPi and MEPe) onboard the Arase satellite, we can comprehensively investigate the fluxes of electrons and ions with different energies. Also, the in-situ electron density can be estimated by using the upper hybrid resonance frequencies detected from the plasma wave spectrum. The geomagnetic storm that commenced on 8 September 2017 has a Dst minimum of -147nT and appears to be a medium-sized magnetic storm at first glance, but it is known that it was a peculiar magnetic storm in various ways. For example, it is an extreme erosion of the plasmasphere to around L=1.5, and a strong SAPS generation.Our previous research suggested that this extreme erosion of the plasmasphere was the result of a convective electric field that continued to penetrate into the magnetic equatorial region for more than 6 hours, however, the reason for the continuation of the convection field was unclear. We therefore compare the evolution of ring current particles during this peculiar magnetic storm to the magnetic storm which commenced on 25 August 2018, which has a similar Dst minimum (-175nT) and erode plasmasphere to around L=2.5., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

令和4年度宇宙科学に関する室内実験シンポジウム（2023年3月6日-7日. オンライン開催), 2023 Symposium on Laboratory Experiment for Space Science (March 6-7, 2023. Online Meeting), 資料番号:SA6000187002, レポート番号: 2

第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催), 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting), 著者人数: 21名, 資料番号: SA6000185020, レポート番号: Ⅲ-5

第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催), 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting), 資料番号: SA6000185001, レポート番号: Ⅰ-1

第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催), 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting), 資料番号: SA6000185003, レポート番号: Ⅰ-3

Magneto-impedance (MI) effect was discovered about 30 years ago and a micro-size magnetic sensor that utilizes this effect becomes commercially available. Nosé et al. (2022, doi: 10.1029/2022JA030809) made some modifications to the commercially available MI sensors to cover the dynamic range of the geomagnetic field. For the period of March 30 to April 27, 2018, they conducted experimental observations of geomagnetic field variations with the MI sensors at the Mineyama observatory in Japan. Data obtained with the MI sensors are compared with those from the fluxgate magnetometer (FGM) that has been working at the observatory. Results showed that the MI sensors can record geomagnetic field variations such as geomagnetic storms, Sq variations, low-latitude positive bays, SSC, and geomagnetic pulsations with a peak-to-peak amplitude of £ 1 nT that are also detected with the FGM. This study revealed that the MI sensor can measure the geomagnetic field variations in a period from a few tens of seconds to a few hours.Using MI sensors, Raspberry Pi, low-cost 24-bit A/D converters, and stable power supply circuits, we developed a magnetometer with approximately $4,000, which is named MIM-Pi (MI sensor Magnetometer with Raspberry Pi). Because of its low cost, MIM-Pi provides an opportunity to construct a dense observation network of geomagnetic field. We are now deploying MIM-Pi in Kanto-Tohoku area. When we apply the magnetoseismology method to the data from such dense observation network, it will be possible to monitor fine structures of the plasma mass density distribution in the inner magnetosphere., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Equatorial plasma bubbles are a phenomenon of plasma density depletion with small-scale density irregularities, normally observed in the equatorial ionosphere. This phenomenon, which impacts satellite-based communications, was observed in the Asia-Pacific region after the largest-on-record January 15, 2022 eruption of the Tonga volcano. We used satellite and ground-based ionospheric observations to demonstrate that an air pressure wave triggered by the Tonga volcanic eruption could cause the emergence of an equatorial plasma bubble. The most prominent observation result shows a sudden increase of electron density and height of the ionosphere several ten minutes to hours before the initial arrival of the air pressure wave in the lower atmosphere. The propagation speed of ionospheric electron density variations was ~ 480–540 m/s, whose speed was higher than that of a Lamb wave (~315 m/s) in the troposphere. The electron density variations started larger in the Northern Hemisphere than in the Southern Hemisphere. The fast response of the ionosphere could be caused by an instantaneous transmission of the electric field to the magnetic conjugate ionosphere along the magnetic field lines. After the ionospheric perturbations, electron density depletion appeared in the equatorial and low-latitude ionosphere and extended at least up to ±25° in geomagnetic latitude., トンガ沖海底火山噴火がもたらした電離圏の穴 --最先端の観測から見えた地圏と宇宙圏のつながり--. 京都大学プレスリリース. 2023-05-24.

第4回観測ロケットシンポジウム（2022年3月14-15日. ハイブリッド開催（JAXA相模原キャンパス& オンライン）), 4th Sounding Rocket Symposium(March 14-15, 2022. Hybrid(in-person & online) Conference (Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 12名, 資料番号: SA6000175010, レポート番号: Ⅱ-5

第4回観測ロケットシンポジウム（2022年3月14-15日. ハイブリッド開催（JAXA相模原キャンパス& オンライン）), 4th Sounding Rocket Symposium(March 14-15, 2022. Hybrid(in-person & online) Conference (Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 17名, 資料番号: SA6000175003, レポート番号: Ⅰ-3

第4回観測ロケットシンポジウム（2022年3月14-15日. ハイブリッド開催（JAXA相模原キャンパス& オンライン）), 4th Sounding Rocket Symposium(March 14-15, 2022. Hybrid(in-person & online) Conference (Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000175021, レポート番号: Ⅴ-1

令和3年度宇宙科学に関する室内実験シンポジウム（2022年2月28日-3月1日. オンライン開催), 2022 Symposium on Laboratory Experiment for Space Science (February 28-March 1, 2022. Online Meeting), 資料番号: SA6000178006, レポート番号: 6