論文 - 佐野　圭

Astronomical 6U CubeSat mission VERTECS: Scientific o bjective a nd p roject status 査読有り 国際誌

Sano K., Nakagawa T., Matsuura S., Takimoto K., Takahashi A., Fuse T., Cordova R., Schulz V.H., Lepcha P., Örger N.C., Nakayama D., Ofosu J., Rosales R.J.G., Areda E., Zangmo P., Fielding E., Chatar K., Otani Y., Kawasaki H., Morelle B., Almonte J.P., Nakagawa S., Tome Y., Karaki S., Narongphun C., Shrestha H.R., Rosa M., Dai D., Bejarano W., Ikeda A., Sato R., Hayashida K., Miyagawa H., Nishioka M., Kurosaki K., Kato I., Ikari S., Tsumura K., Jikuya I., Matsuhara H., Enokidani U., Tanaka H., Hirose Y., Ojika A., Tsumoto A., Iwaki T., Ohara Y., Cho M., Kitamura K., Masui H., Teramoto M., Yamauchi T., Hashimoto R., Fukumoto E., Leonel Z., Oho A., Yabumoto S., Masuno H., Arakawa C., Miyamoto K., Wada T., Isobe N., Miyazaki Y., Funase R., Kawahara H., Hirako K., Yatsu Y., Aoyanagi Y.

Proceedings of SPIE the International Society for Optical Engineering   13092   2024年01月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

We describe scientific o bjective a nd p roject s tatus o f a n a stronomical 6 U C ubeSat m ission V ERTECS (Visible Extragalactic background RadiaTion Exploration by CubeSat). The scientific g oal o f V ERTECS i s t o reveal the star-formation history along the evolution of the universe by measuring the extragalactic background light (EBL) in the visible wavelength. Earlier observations have shown that the near-infrared EBL is several times brighter than integrated light of individual galaxies. As candidates for the excess light, first-generation s tars in the early universe or low-redshift intra-halo light have been proposed. Since these objects are expected to show different e mission s pectra i n v isible w avelengths, m ulti-color v isible o bservations a re c rucial t o r eveal t he origin of the excess light. Since detection sensitivity of the EBL depends on the product of the telescope aperture and the field o f v iew, i t i s p ossible t o o bserve i t w ith a s mall b ut w ide-field te lescope sy stem th at ca n be mounted on the limited volume of CubeSat. In VERTECS mission, we develop a 6U CubeSat equipped with a 3U-sized telescope optimized for observation of the visible EBL. The bus system composed of onboard computer, electric power system, communication subsystem, and structure is based on heritage of series of CubeSats developed at Kyushu Institute of Technology in combination with high-precision attitude control subsystem and deployable solar array paddle required for the mission. The VERTECS mission was selected for JAXA-Small Satellite Rush Program (JAXA-SMASH Program), a new program that encourages universities, private companies and JAXA to collaborate to realize small satellite missions utilizing commercial small launch opportunities, and to diversify transportation services in Japan. We started the satellite development in December 2022 and plan to launch the satellite in FY2025.

DOI： 10.1117/12.3014708

Scopus

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The isotropic interplanetary dust cloud and near-infrared extragalactic background light observed with COBE/DIRBE 査読有り

Sano K., Matsuura S., Yomo K., Takahashi A.

Astrophysical Journal   901 ( 2 )   2020年10月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020. The American Astronomical Society. All rights reserved.. We report observation of isotropic interplanetary dust (IPD) by analyzing the infrared (IR) maps of the Diffuse Infrared Background Experiment (DIRBE) on board the Cosmic Background Explorer (COBE) spacecraft. To search for the isotropic IPD, we perform new analysis in terms of the solar elongation angle (), because we expect the zodiacal light (ZL) intensity from the isotropic IPD to decrease as a function of . We use the DIRBE weekly averaged maps covering 64° ≲ ≲ 124° and inspect the dependence of residual intensity after subtracting conventional ZL components. We find the dependence of the residuals, indicating the presence of the isotropic IPD. However, the mid-IR dependence is different from that of the isotropic IPD model at ⪆ 90°, where the residual intensity increases as a function of . To explain the observed dependence, we assume a spheroidal IPD cloud showing higher density farther away from the Sun. We estimate the intensity of the near-IR extragalactic background light (EBL) by subtracting the spheroidal component, assuming the spectral energy distribution from the residual brightness at 12 μm. The EBL intensity is derived as 45-8+11, 21-4+3, and 15 ± 3, nWm-2, sr-1 at 1.25, 2.2, and 3.5 μm, respectively. The EBL is still a few times larger than the integrated light of normal galaxies, suggesting the existence of unaccounted-for extragalactic sources.

DOI： 10.3847/1538-4357/abad3d

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Spectral study of scattered light by interstellar dust grains 査読有り

Sano K.

Proceedings of the International Astronomical Union   15 ( S341 )   302 - 303   2019年01月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Interstellar dust is traced by not only thermal emission but also scattered light. The scattered light spectrum observed from ultraviolet (UV) to near-infrared (IR) is useful to constrain some dust properties, such as size distribution, albedo, and composition. Milky Way Galaxy is a unique environment to observe the diffuse scattered light because we can extract it by removing the contribution of starlight. We have observed the UV to near-IR scattered light with space instruments, including Diffuse Infrared Background Experiment (DIRBE), Hubble Space Telescope (HST), and Multi-purpose Infra-Red Imaging System (MIRIS). The scattered light spectrum is marginally consistent with prediction from a recent dust model including carbonaceous and silicate grains with polycyclic aromatic hydrocarbon (PAH). Based on the MIRIS observation of a diffuse cloud, we compare the scattered light color with the dust model with or without grains larger than 1 micrometer. The result shows that the color is consistent with the model without the large grains, which is consistent with recent simulations of dust growth in low-density regions. However, some observations have shown the spectral excess at ∼ 0.6 micrometer wavelength, suggesting the presence of extended red emission (ERE) which cannot be explained by the conventional dust model.

DOI： 10.1017/S1743921319002990

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Galactic Latitude Dependence of Near-infrared Diffuse Galactic Light: Thermal emission or scattered light? 査読有り

Sano K., Matsuura S.

Astrophysical Journal   849 ( 1 )   2017年11月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017. The American Astronomical Society. All rights reserved. Near-infrared (IR) diffuse Galactic light (DGL) consists of scattered light and thermal emission from interstellar dust grains illuminated by the interstellar radiation field (ISRF). At 1.25 and 2.2 mm, a recent observational study shows that intensity ratios of the DGL to interstellar 100 mm dust emission steeply decrease toward high Galactic latitudes (b). In this paper, we investigate the origin(s) of the b-dependence on the basis of models of thermal emission and scattered light. Combining a thermal emission model with the regional variation of the polycyclic aromatic hydrocarbon abundance observed with Planck, we show that the contribution of the near-IR thermal emission component to the observed DGL is lower than ~20%. We also examine the b-dependence of the scattered light, assuming a plane-parallel Galaxy with smooth distributions of the ISRF and dust density along the vertical direction, and assuming a scattering phase function according to a recently developed model of interstellar dust. We normalize the scattered light intensity to the 100 mm intensity corrected for deviation from the cosecant-b law according to the Planck observation. As the result, the present model that considers the b-dependence of dust and the ISRF properties can account for the observed b-dependence of the near-IR DGL. However, the uncertainty in the correction for the 100 mm emission is large, and other normalizing quantities may be appropriate for a more robust analysis of the DGL.

DOI： 10.3847/1538-4357/aa906c

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FIRST DETECTION OF GALACTIC LATITUDE DEPENDENCE OF NEAR-INFRARED DIFFUSE GALACTIC LIGHT FROM DIRBE RENALYSIS 査読有り

Sano K., Matsuura S., Tsumura K., Arai T., Shirahata M., Onishi Y.

Astrophysical Journal Letters   821 ( 1 )   2016年04月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2016. The American Astronomical Society. All rights reserved. Observational study on near-infrared (IR) scattering properties of interstellar dust grains has been limited due to its faintness. Using all-sky maps obtained from the Diffuse Infrared Background Experiment, we investigate the scattering property from diffuse Galactic light (DGL) measurements at 1.25, 2.2, and 3.5 μm, in addition to our recent analyses of diffuse near-IR emission. As a result, we first find that the intensity ratios of near-IR DGL to 100 μm emission increase toward low Galactic latitudes at 1.25 and 2.2 μm. The derived latitude dependence can be reproduced by a scattered light model of interstellar dust with a large scattering asymmetry factor g ≡ 'cos θ' of 0.8-0.3+0.2 at 1.25 and 2.2 μm, assuming an infinite Galaxy disk as an illuminating source. The derived asymmetry factor is comparable to the values obtained in the optical, but several times larger than that expected from a recent dust model. Since a possible latitude dependence of ultraviolet-excited dust emission at 1.25 and 2.2 μm would reduce the large asymmetry factor to the reasonable value, our result may indicate the first detection of such an additional emission component in the diffuse interstellar medium.

DOI： 10.3847/2041-8205/821/1/L11

Scopus

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MEASUREMENTS OF DIFFUSE SKY EMISSION COMPONENTS IN HIGH GALACTIC LATITUDES AT 3.5 and 4.9 μm USING DIRBE AND WISE DATA 査読有り

Sano K., Kawara K., Matsuura S., Kataza H., Arai T., Matsuoka Y.

Astrophysical Journal   818 ( 1 )   2016年02月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2016. The American Astronomical Society. All rights reserved. Using all-sky maps obtained from the Cosmic Background Explorer/Diffuse Infrared Background Experiment (DIRBE) at 3.5 and 4.9 μm, we present a reanalysis of diffuse sky emissions such as zodiacal light (ZL), diffuse Galactic light (DGL), integrated starlight (ISL), and isotropic residual emission including the extragalactic background light (EBL). Our new analysis, which includes an improved estimate of ISL using the Wide-field Infrared Survey Explorer data, enabled us to find the DGL signal in a direct linear correlation between diffuse near-infrared and 100 μm emission at high Galactic latitudes (|b| > 35°). At 3.5 μm, the high-latitude DGL result is comparable to the low-latitude value derived from the previous DIRBE analysis. In comparison with models of the DGL spectrum assuming a size distribution of dust grains composed of amorphous silicate, graphite, and polycyclic aromatic hydrocarbon (PAH), the measured DGL values at 3.5 and 4.9 μm constrain the mass fraction of PAH particles in the total dust species to be more than ∼2%. This was consistent with the results of Spitzer/IRAC toward the lower Galactic latitude regions. The derived residual emission of 8.9 ± 3.4 nWm-2 sr-1 at 3.5 μm is marginally consistent with the level of integrated galaxy light and the EBL constraints from the γ-ray observations. The residual emission at 4.9 μm is not significantly detected due to the large uncertainty in the ZL subtraction, the same as in previous studies. Combined with our reanalysis of the DIRBE data at 1.25 and 2.2 μm, the residual emission in the near-infrared exhibits the Rayleigh-Jeans spectrum.

DOI： 10.3847/0004-637X/818/1/72

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DERIVATION of A LARGE ISOTOPIC DIFFUSE SKY EMISSION COMPONENT at 1.25 and 2.2 μm from the COBE/DIRBE DATA 査読有り

Sano K., Kawara K., Matsuura S., Kataza H., Arai T., Matsuoka Y.

Astrophysical Journal   811 ( 2 )   2015年10月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

� 2015. The American Astronomical Society. All rights reserved. Using all-sky maps obtained with COBE/DIRBE, we reanalyzed the diffuse sky brightness at 1.25 and which consists of zodiacal light, diffuse Galactic light (DGL), integrated starlight (ISL), and isotropic emission including the extragalactic background light. Our new analysis including an improved estimate of the DGL and the ISL with the 2MASS data showed that deviations of the isotropic emission from isotropy were less than 10% in the entire sky at high Galactic latitude (). We derived the DGL to 100 μm brightness ratios of ∼4.79 and ∼1.49 n W m-2 MJy-1 at 1.25 and 2.2 μm, respectively. The result of our analysis revealed a significantly large isotropic component at 1.25 and with intensities of 60.15 16.14 and respectively. This intensity is larger than the integrated galaxy light, upper limits from γ-ray observation, and potential contribution from exotic sources (i.e., Population III stars, intrahalo light, direct collapse black holes, and dark stars). We therefore conclude that the excess light may originate from the local universe: the Milky Way and/or the solar system.

DOI： 10.1088/0004-637X/811/2/77

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Measurement of the zodiacal light absolute intensity through Fraunhofer line spectroscopy of the night sky with the Hale telescope 査読有り 国際誌

Hanzawa M., Matsuura S., Takahashi A., Chary R.R., Sano K., Takimoto K., Tome Y.

Publications of the Astronomical Society of Japan   76 ( 3 )   353 - 364   2024年06月

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Measuring the absolute brightness of the zodiacal light (ZL), which is the sunlight scattered by interplanetary dust particles, is important not only for understanding the physical properties of the dust but also for constraining the extragalactic background light (EBL) by subtracting the ZL foreground. We describe the results of high-resolution spectroscopic observations of the night sky in the wavelength range of 300-900 nm with the double spectrograph on the Hale telescope to determine the absolute brightness of the ZL continuum spectra from the Fraunhofer absorption line intensities. The observed fields are part of the fields observed by the Spitzer Space Telescope for the EBL study. Assuming that the spectral shape of the zodiacal light is identical to the solar spectrum in a narrow region around the Fraunhofer lines, we decomposed the observed sky brightness into multiple emission components by amplitude parameter fitting with spectral templates of the airglow, ZL, diffuse Galactic light, integrated starlight, and other isotropic components including EBL. As a result, the ZL component with the Ca ii λλ 393.3, 396.8 nm Fraunhofer lines around 400 nm is clearly separated from the others in all fields with uncertainties around 20%, mainly due to the template errors and the time variability of the airglow. The observed ZL brightness in most of the observed fields is consistent with the modeled ZL brightness calculated by combining the most conventional ZL model at 1250 nm based on the Diffuse Infrared Background Experiment and the observational ZL template spectrum based on the Hubble Space Telescope. However, the ecliptic plane observation is considerably fainter than the ZL model, and this discrepancy is discussed in terms of the optical properties of the interplanetary dust accreted in the ecliptic plane.

DOI： 10.1093/pasj/psae016

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NASA観測ロケット実験CIBER-2―光学性能評価―

玉井 桃子, 松浦 周二, 橋本 遼, 中川 智矢, 中畑 秀太, 花井 翔, 瀧本 幸司, 佐野 圭, 中川 俊輔, 津村 耕司, 高橋 葵, 和田 武彦, ZEMCOV Michael, BOCK James, CIBER-2 collaboration

観測ロケットシンポジウム2023 講演集 ( 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS) )   2024年02月

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記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

レポート番号: Ⅴ-3

CiNii Research

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VERTECS: A COTS-based payload interface board to enable next generation astronomical imaging payloads 国際誌

Fielding E., Schulz V.H., Chatar K.A.A., Sano K., Hanazawa A.

Proceedings of SPIE - The International Society for Optical Engineering   13101   2024年01月

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Due to advances in observation and imaging technologies, modern astronomical satellites generate large volumes of data. This necessitates efficient onboard data processing and high-speed data downlink. Reflecting this trend is the Visible Extragalactic background RadiaTion Exploration by CubeSat (VERTECS) 6U Astronomical Nanosatellite. Designed for the observation of Extragalactic Background Light (EBL), this mission is expected to generate a substantial amount of image data, particularly within the confines of CubeSat capabilities. This paper introduces the VERTECS Camera Control Board (CCB), an open-source payload interface board leveraging Commercial Off-The-Shelf (COTS) components, with a Raspberry Pi Compute Module 4 at its core. The VERTECS CCB hardware and software have been designed from the ground up to serve as the sole interface between the VERTECS bus system and astronomical imaging payload, while providing compute capability not usually seen in nanosatellites of this class. Responsible for mission data processing, it will facilitate high-speed data transfer from the imaging payload via gigabit Ethernet, while also providing a high-bitrate serial connection to the payload X-band transmitter for mission data downlink. Additional interfaces for secondary payloads are provided via USB-C and standard 15-pin camera connectors. The Raspberry Pi embedded within the VERTECS CCB operates on a standard Linux distribution, streamlining the software development process. Beyond addressing the current mission’s payload control and data handling requirements, the CCB sets the stage for future missions with heightened data demands. Furthermore, it supports the adoption of machine learning and other compute-intensive applications in orbit. This paper delves into the development of the VERTECS CCB, offering insights into the design and validation of this next-generation payload interface, to ensure that it can survive the rigors of space flight.

DOI： 10.1117/12.3019471

Scopus

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Microwave Patch Antenna Placement on 6U CubeSat 国際誌

Nakayama D., Sano K., Matsushima T., Fukumoto Y.

2024 International Conference on Electronics Packaging, ICEP 2024   193 - 194   2024年01月

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Kyushu Institute of Technology (Kyutech) is developing a 6U CubeSat that is named 'VERTECS' (Visible Extragalactic background RadiaTion Exploration by CubeSat). This is an astronomical CubeSat designed to reveal star formation history by observing visible extragalactic background light [1] and the first satellite for Kyutech to rely on not UHF (around 400 MHz) but only microwave (>1 GHz) to communicate between the satellite and ground station. Microstrip patch antennas are adopted on this CubeSat due to desired characteristics such as low profile, lightweight, and non-deployable structure. However due to the performance of the microstrip patch antenna is limited such as directional radiation pattern and narrow operational bandwidth, the placement of the antenna on CubeSat is more critical compared to that of the conventional antenna for UHF communication, such as dipole and monopole antenna. In this paper, we describe choosing the antenna placement while considering antenna performance, including the coupling of transmission and reception antenna.

DOI： 10.23919/ICEP61562.2024.10535673

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VERTECS: Thermal modeling and analysis to enhance mission efficiency through temperature control strategies of a 6U CubeSat with visible light telescope 査読有り 国際誌

Rosales R.J.G., Kawasaki H., Karaki S., Rosa M., Fielding E., Chatar K., Matsuura S., Hirose Y., Masui H., Sano K., Nakagawa T., Cho M.

Proceedings of SPIE the International Society for Optical Engineering   13099   2024年01月

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This study focuses on optimizing the thermal performance of the Visible Extragalactic background RadiaTion Exploration by CubeSat (VERTECS), a 6U CubeSat with a 3U telescope for observing Extragalactic Background Light. Aside from dealing with satellite survivability in the space environment, the payload includes a CMOS sensor which requires operational temperatures of less than 0°C to minimize the noise due to temperature dependent dark current in observation data. The payload telescope lens optical system is designed to operate within a temperature range of -10°C to 35°C. The thermal analysis considers solar radiation, internal heat dissipation, and external factors in various orbital scenarios. The investigation identifies potential temperature fluctuations and proposes passive thermal control strategies, including enhanced coatings and radiators. By implementing tailored strategies, this research enhances the reliability and longevity of 6U CubeSat missions, advancing small satellite technology in space exploration and scientific research.

DOI： 10.1117/12.3018823

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VERTECS: Operational and Power Management Strategy 査読有り 国際誌

Nakagawa S., Narongphun C., Leonel Z., Shrestha H.R., Kato I., Fukumoto E., Cordova R., Schulz V.H., Örger N.C., Sano K., Nakagawa T., Takimoto K., Matsuura S., Tsumura K., Takahashi A., Nakayama D., Ojika A., Sato R., Chatar K.A.A., Otani Y., Fielding E., Hayashida K., Tanaka H., Areda E.E., Morelle B.B.A., Kawasaki H., Enokidani U., Rosales R.J.G., Shohei K., Jikuya I.

Proceedings of SPIE the International Society for Optical Engineering   13092   2024年01月

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Extragalactic Background Light (EBL), the cumulative light from outside the galaxy, is a crucial observational target for understanding the history of the universe. We are developing a CubeSat; VERTECS (Visible Extragalactic background RadiaTion Exploration by CubeSat) with a 6U size (approximately 10 × 20 × 30 cm), equipped with Solar Array Wings (SAW). Our mission is to conduct extensive observations of the visible EBL. The satellite is designed to operate in a sun-synchronous orbit at an altitude of 500-680 km (approximately 15 orbits per day) and observe the EBL on the shadow side to avoid stray light from the Sun and Earth. To observe EBL, a high-performance CMOS sensor, attitude control devices, and high-speed communication equipment X-band are essential. We should note that these components these components consume a significant amount of power. Therefore, some strategic operational plans are necessary to operate this CubeSat within the limited power resources. In addition, VERTECS needs to meet its mission requirements, conducting 10 observations, 4 data downlinks, and 1 command uplink within a day. We have constructed some operational scenarios utilizing attitude control and SAW to meet these requirements, and we also constructed a power budget simulation for VERTECS. In this presentation, we describe how we plan to operate VERTECS utilizing the subsystems and the results of the power simulation during the operation.

DOI： 10.1117/12.3017332

Scopus

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VERTECS: Development Status of the Mission Payload Specialized in Visible EBL Observation 査読有り 国際誌

Takimoto K., Hirose Y., Iwaki T., Kawasaki H., Matsuura S., Nakagawa S., Nakagawa T., Ojika A., Sato R., Takahashi A., Tome Y., Tsumoto A., Tsumura K., Sano K.

Proceedings of SPIE the International Society for Optical Engineering   13092   2024年01月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

The extragalactic background light (EBL) is the integrated emission from all objects outside of the Milky Way galaxy and is a crucial observational quantity in the broader study of the history of cosmic structures. In the near-infrared EBL, there have been measurements of an emission component several times brighter than the cumulative light from extragalactic galaxies. This unknown radiation component has led to proposals for candidate source objects, such as first stars and galactic halo brown dwarfs. These source objects exhibit distinct radiation spectra in the visible wavelength. The VERTECS (Visible Extragalactic background RadiaTion Exploration by CubeSat) project is focused on continuously observing the visible EBL using a wide-field small telescope on a 6U CubeSat. The primary characteristic of this telescope is its high-throughput (SΩ > 10⁻⁶ m²sr). The 3U-sized optical telescope onboard this satellite consists of a lens optics with a total field of view of 6^◦ × 6^◦, pixel field of view of 11” × 11”, a highly sensitive and low-noise detector module, and a baffle to eliminate stray light from the Sun and Earth. Additionally, color filters divide the wavelength range from 400 to 800 nm into four bands. Our observation strategy involves capturing 60-second exposure images while shifting the observed field by 3^◦ increments and stacking the acquired images to perform photometry in the four bands. Thus far, most of the telescope design has met the required specifications, and the project is currently advancing towards the production of an engineering model. This project was selected in the JAXA-SMASH and is currently progressing in satellite development with a planned launch in the 2025 fiscal year. In this presentation, we will report on the strategy for observing the visible EBL, the progress in the development of the optical telescope, and the future plans.

DOI： 10.1117/12.3016614

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VERTECS: Design and development of 6U CubeSat structure for observations of extragalactic background light 査読有り 国際誌

Kawasaki H., Areda E.E., Matsuhara H., Masui H., Takimoto K., Morelle B.B.A., Matsuura S., Nakagawa T., Enokidani U., Hirose Y., Sano K.

Proceedings of SPIE the International Society for Optical Engineering   13092   2024年01月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

The extragalactic background light (EBL) is the integrated emission from out of our Galaxy.Its observation is crucial for revealing the history of star-formation from the early universe to the present epoch. Visible Extragalactic background RadiaTion Exploration by CubeSat (VERTECS) is a 6U astronomical satellite to observe the EBL in visible wavelength from 0.4 µm to 0.8 µm. To observe the EBL, a telescope with 11 lenses and a high-performance CMOS sensor are equipped within 3U volume. The remaining 3U comprises the bus section mainly based on the bus design previously developed at Kyushu Institute of Technology. This paper describes the design and verification processes of the structure and thermal model of the satellite to fulfill the interface and mission requirements. From a mission perspective, the precise attitude and orbit control system unit is mounted on the same interface plate as the telescope to meet stringent pointing stability requirements during observations. The purpose of the stiff design of this interface plate is to minimize structural deformation. Furthermore, integrating multiple external antennas with relatively large X-band and S-band communication units require effective routing harness management. Static stress analysis is performed under the quasi-static loading condition. In addition, modal analysis is also conducted to fulfill the strength and stiffness requirements of the launcher. A series of mechanical environmental tests (shock, random, and sinusoidal vibrations) have been conducted to verify the design and analysis results. The results showed that designed model can fundamentally withstand the launch environment.

DOI： 10.1117/12.3016648

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The Cosmic Infrared Background ExpeRiment 2 (CIBER-2): Status of Recent Flights 査読有り 国際誌

Matsuura S., Bock J.J., Cooray A., Fazar C., Feder R.M., Hashimoto R., Heaton G., Hristov V., Kawano Y., Korngut P., Lee D.H., Matsumi C., Mercado D., Nakagawa S., Nakagawa T., Nakahata S., Nguyen C.H., Noda K., Patru D., Park W.K., Sano K., Takahashi A., Takimoto K., Tamai M., Tsumura K., Zemcov M.

Proceedings of SPIE the International Society for Optical Engineering   13092   2024年01月

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

The extragalactic background light (EBL) is the integrated diffuse emissions from unresolved stars, galaxies, and intergalactic matter along the line of sight. The EBL is regarded as consisting of stellar emissions and thus an important observational quantity for studying global star formation history throughout cosmic time. Intensity and anisotropy in the near-infrared EBL as measured by the Cosmic Infrared Background ExpeRiment (CIBER), NASA’s sounding rocket experiment, and previous infrared satellites exceed the predicted signal from galaxy clustering alone. The objective of CIBER-2 is to unveil the EBL excess by observing it at extended wavelengths into the visible spectrum with an accuracy better than CIBER. The onboard instrument of CIBER-2 comprises a 28.5-cm telescope cooled to 90K, and three HAWAII-2RG detectors coupled with dual-band filters for photometric mapping observations in six wavebands simultaneously and with linear variable filters for low-resolution spectroscopy. Although CIBER-2 made a successful first flight from White Sands Missile Range in New Mexico in 2021, technical problems such as contamination of thermal radiation from the rocket chassis and degradation of the mirror coat were recognized. Despite a successful second flight in 2023 solving the problems with the revised onboard instrument, the experiment was aborted because of trouble with the rocket tracking system. In this paper, we describe the parachute-recovered payload rebuilt after the second flight and the testing, and we report the successful flight on May 5th 2024.

DOI： 10.1117/12.3017526

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A Framework for Space Education Integrating Science and Engineering through the development of 2U CubeSat 査読有り 国際誌

Kitamura K., Masui H., Abe S., Uozumi T., Teramoto M., Fujimoto A., Sano K., Yoshikawa A., Cho M.

Proceedings of the International Astronautical Congress Iac   2-B   1305 - 1309   2024年01月

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

In order to develop practical space human resources on an interdisciplinary of science and engineering fields, Kyushu Institute of Technology and the Kyushu University collaborated to implement a 2U-size CubeSat development program for undergraduate students. In this program, students from different universities and different disciplines work together to develop satellites to accomplish full-scale scientific missions. To guide this program, complementary educational programs in science and engineering were established, and the two universities collaborated to educate the students. In this paper we report the outline and implementation of this initiative.

DOI： 10.52202/078378-0164

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Heliocentric distance dependence of zodiacal light observed by Hayabusa2# 査読有り 国際誌

Tsumura K., Matsuura S., Sano K., Iwata T., Yano H., Kitazato K., Takimoto K., Yamada M., Morota T., Kouyama T., Hayakawa M., Yokota Y., Tatsumi E., Matsuoka M., Sakatani N., Honda R., Kameda S., Suzuki H., Cho Y., Yoshioka K., Ogawa K., Shirai K., Sawada H., Sugita S.

Earth, Planets and Space   75 ( 1 )   2023年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Zodiacal light (ZL) is sunlight scattered by interplanetary dust particles (IDPs) at optical wavelengths. The spatial distribution of IDPs in the Solar System may hold an important key to understanding the evolution of the Solar System and material transportation within it. The number density of IDPs can be expressed as n(r) ∼ r-α , and the exponent α∼ 1.3 was obtained by previous observations from interplanetary space by Helios 1/2 and Pioneer 10/11 in the 1970s and 1980s. However, no direct measurements of α based on ZL observations from interplanetary space outside Earth’s orbit have been performed since then. Here, we introduce initial results for the radial profile of the ZL at optical wavelengths observed over the range 0.76 - 1.06 au by ONC-T aboard the Hayabusa2# mission in 2021-2022. The ZL brightness we obtained is well reproduced by a model brightness, although there is a small excess of the observed ZL brightness over the model brightness at around 0.9 au. The radial power-law index we obtained is α= 1.30 ± 0.08 , which is consistent with previous results based on ZL observations. The dominant source of uncertainty arises from the uncertainty in estimating the diffuse Galactic light (DGL). Graphical Abstract: [Figure not available: see fulltext.]

DOI： 10.1186/s40623-023-01856-x

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Near-infrared Polarization Charateristics of the Zodiacal Light Observed with DIRBE/COBE 査読有り 国際誌

Takimoto K., Matsuura S., Sano K., Feder R.M.

Astrophysical Journal   944 ( 2 )   2023年02月

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記述言語：英語   掲載種別：研究論文（学術雑誌）

We report near-infrared polarization of the zodiacal light (ZL) measured from space by the Diffuse Infrared Background Experiment (DIRBE) on board the Cosmic Background Explorer in photometric bands centered at 1.25, 2.2, and 3.5 μm. To constrain the physical properties of interplanetary dust, we use DIRBE Weekly Sky Maps to investigate the solar elongation (ϵ), ecliptic latitude (β), and wavelength (λ) dependence of ZL polarization. We find that the polarization of the ZL varies as a function of ϵ and β, consistent with observed polarization at λ = 550 nm. While the polarization dependence on wavelength at (ϵ, β) = (90°, 0°) is modest (increasing from 17.7% ± 0.2% at 1.25% μm to 21.0% ± 0.3% at 3.5 μm), the variation is more pronounced at the north ecliptic pole (23.1% ± 1.6%, 35.1% ± 2.0%, and 39.3% ± 2.1% at 1.25, 2.2, and 3.5 μm, respectively). The variation in ZL polarization with wavelength is not explained by either Rayleigh scattering or absorptive particles larger than 10 μm.

DOI： 10.3847/1538-4357/acb937

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Data downlink prioritization using image classification on-board a 6U CubeSat 国際誌

Chatar K.A.A., Fielding E., Sano K., Kitamura K.

Proceedings of SPIE - The International Society for Optical Engineering   12729   2023年01月

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Nanosatellites are proliferating as low-cost dedicated sensing systems with lean development cycles. Kyushu Institute of Technology (Kyutech) and collaborators have launched a joint venture for a nanosatellite mission, Visible Extragalactic background RadiaTion Exploration by CubeSat (VERTECS). The primary mission is to elucidate the formation history of stars by observing the optical-wavelength cosmic background radiation. The VERTECS satellite will be equipped with a small-Aperture telescope and a high-precision attitude control system to capture the astronomical data for analysis on the ground. However, nanosatellites are limited by their onboard memory resources and downlink speed capabilities. Additionally, due to a limited number of ground stations, the satellite mission will face issues meeting the required data budget for mission success. To alleviate this issue, we propose an on-orbit system pipeline to autonomously classify and then compress desirable image data for downlink prioritization and optimization. The system comprises a prototype Camera Controller Board (CCB) which carries a Raspberry Pi Compute Module 4 which is used for classification and compression. The system uses a lightweight Convolutional Neural Network (CNN) model to classify and determine the desirability of captured image data. The model is designed to be lean and robust to reduce the computational and memory load on the satellite. The model is trained and tested on a novel star field dataset consisting of data captured by the Sloan Digital Sky Survey (SDSS). The dataset is meant to simulate the expected data produced by the 6U satellite. The compression step implements GZip, RICE or HCOMPRESS compression, which are standards for astronomical data. Preliminary testing on the proposed CNN model results in a validation classification accuracy of 100% on the star field dataset, with compression ratios of 3.99, 5.16 and 5.43 for GZip, RICE and HCOMPRESS that were achieved on tested FITS image data.

DOI： 10.1117/12.2684047

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