HISAKI Project Team
Profile Information
- Affiliation
- Professor, College of Science Department of Physics, Rikkyo University教授, 物理学専攻博士課程後期課程, 理学研究科Professor, Field of Study: Physics, Graduate School of ScienceSpecially Appointed Professor, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(Concurrent)Specially Appointed Professor, Institute of Space and Astronautical Science
- Degree
- 博士(理学)(東京大学)
- Researcher number
- 30455464
- J-GLOBAL ID
- 201101036293959472
- researchmap Member ID
- 6000028006
Research Interests
1Research Areas
1Research History
6-
Apr, 2018 - Present
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Apr, 2018 - Present
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Apr, 2018 - Present
Education
3-
Apr, 1997 - Mar, 2002
Papers
132-
Icarus, 420, Sep 15, 2024Various natural effects gradually alter the surfaces of asteroids exposed to the space environment. These processes are collectively known as space weathering. The influence of space weathering on the observed spectra of C-complex asteroids remains uncertain. This has long hindered our understanding of their composition and evolution through ground-based telescope observations. Proximity observations of (162173) Ryugu by the telescopic Optical Navigation Camera (ONC-T) onboard Hayabusa2 and that of (101955) Bennu by MapCam onboard Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) found opposite spectral trends of space weathering; Ryugu darkened and reddened while Bennu brightened and blued. How the spectra of Ryugu and Bennu evolved relative to each other would place an important constraint for understanding their mutual relationship and differences in their origins and evolutions. In this study, we compared the space weathering trends on Ryugu and Bennu by applying the results of cross calibration between ONC-T and MapCam obtained in our companion paper. We show that the average Bennu surface is brighter by 18.0 ± 1.5% at v band (550 nm) and bluer by 0.18 ± 0.03 μm−1 (in the 480–850 nm spectral slope) than Ryugu. The spectral slopes of surface materials are more uniform on Bennu than on Ryugu at spatial scales larger than ∼1 m, but Bennu is more heterogeneous at scales below ∼1 m. This suggests that lateral mixing of surface materials due to resurfacing processes may have been more efficient on Bennu. The reflectance−spectral slope distributions of craters on Ryugu and Bennu appeared to follow two parallel trend lines with an offset before cross calibration, but they converged to a single straight trend without a bend after cross calibration. We show that the spectra of the freshest craters on Ryugu and Bennu are indistinguishable within the uncertainty of cross calibration. These results suggest that Ryugu and Bennu initially had similar spectra before space weathering and that they evolved in completely opposite directions along the same trend line, subsequently evolving into asteroids with different disk-averaged spectra. These findings further suggest that space weathering likely expanded the spectral slope variation of C-complex asteroids, implying that they may have formed from materials with more uniform spectral slopes.
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Spectrochimica Acta Part B: Atomic Spectroscopy, 107049-107049, Sep, 2024
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 18-18, Aug 21, 2024
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Icarus, 417 116122-116122, Jul, 2024
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Space Science Reviews, 220(1), Jan 24, 2024Abstract Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum $\varDelta $V capability of $600\text{ ms}^{-1}$. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.
Misc.
83Research Projects
17-
科学研究費助成事業, Apr, 2018 - Mar, 2023
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科学研究費助成事業, 日本学術振興会, Apr, 2019 - Mar, 2022
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アストロバイオロジーセンター サテライト研究, 自然科学研究機構, Apr, 2018 - Mar, 2021
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JAXA戦略的基礎開発予算, 文部科学省, Apr, 2019 - Mar, 2020
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JAXA戦略的基礎開発予算, 宇宙航空研究開発機構, Apr, 2018 - Mar, 2019
