隼鸟2号/NIRS3光谱仪的在轨校准更新：小行星(162173)龙宫的新全球近红外光度特性
Updated in-flight calibration of the Hayabusa2/NIRS3 spectrometer: new global near-infrared photometric properties of asteroid (162173) Ryugu
浏览论文内容
中文总结 AI 辅助
本研究更新隼鸟2号NIRS3光谱仪的在轨校准，修正两次着陆后数据偏差，揭示龙宫表面存在弱东西二分性，为后续小行星观测提供支持。
中文摘要 AI 辅助
搭载于隼鸟2号的近红外光谱仪（NIRS3）对小行星(162173)龙宫开展观测，重点寻找含水矿物的特征。然而在任务期间，望远镜光学导航相机（ONC-T）与NIRS3测得的绝对反射率存在系统偏差，且两次着陆操作改变了仪器响应，使得第二次着陆后的数据可靠性降低。修正这些问题对解读龙宫表面细微的光谱差异、更好地理解碳质小行星的起源与演化、为隼鸟2号#任务后续对小行星(98943)鸟船星和1998 KY26的观测提供支持至关重要。我们利用不同任务阶段的龙宫观测数据进行相对校准，利用月球观测数据进行绝对校准；将第一次地球重力助推期间获取的月球光谱，与基于月球轨道器及地基数据构建的光度模型模拟光谱进行对比。随后将更新后的校准应用于隼鸟2号近距阶段的全部数据集，实现了可分辨盘面的全球及区域光度分析。结果显示，第一次和第二次着陆后获取的数据在2μm处分别需要5.4±1.8%和10.3±0.4%的缩小修正；绝对校准表明，与原始校准相比，NIRS3的反射率被低估了约8%。我们的新光度参数与此前研究一致，且显示相位比和相位变红存在弱东西二分性，表明龙宫东半球的表面粗糙度更高，细粒 regolith（表土）丰度更高。
英文摘要
The Near InfraRed Spectrometer (NIRS3) onboard Hayabusa2 observed asteroid (162173) Ryugu, searching especially for signatures of water-bearing minerals. However, during the mission, absolute reflectance measured by the Telescopic Optical Navigation Camera (ONC-T) and NIRS3 showed a systematic offset. Additionally, touchdown operations have modified the instrumental response, which has made post-second-touchdown data less reliable. Correction of these issues is crucial to interpret the subtle spectroscopic differences across the surface, better understand the origin and evolution of carbonaceous asteroids, and support the Hayabusa2$\sharp$ mission's future observations of the asteroids (98943) Torifune and 1998 KY26. We used Ryugu observations at different mission phases for relative calibrations and lunar observations for the absolute calibration. Moon spectra acquired during the first Earth swing-by were compared to simulated ones from photometric models based on lunar orbiter and ground-based data. We then applied the updated calibration to the full Hayabusa2 proximity phase dataset, enabling disk-resolved global and regional photometric analyses. We showed that the data obtained following the first and second touchdowns required downscaled corrections of $5.4 \pm 1.8 $% and $10.3 \pm 0.4 $% at 2 $μm$, respectively, while the absolute calibration revealed that NIRS3 reflectance was underestimated by about 8% compared with the original calibration. Our new photometric parameters are consistent with previous studies and indicate a weak east-west dichotomy in phase ratio and phase reddening, pointing to higher surface roughness and higher abundance of fine-grained regolith in Ryugu eastern hemisphere.
发表机构
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)（宇宙科学研究所（ISAS），日本宇宙航空研究开发机构（JAXA））
- Instituto de Astrofísica de Canarias (IAC)（加那利天体物理学研究所 (IAC)）
- Department of Astrophysics, University of La Laguna（拉帕尔马大学天体物理系）
- Department of Earth and Planetary Science, The University of Tokyo（东京大学地球行星科学系）
- LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, CY Cergy Paris Université（巴黎天文台 LIRA，PSL 大学，索邦大学，巴黎西岱大学，法国国家科学研究中心，CY 塞吉巴黎大学）
机构由 AI 辅助整理，请以论文原文为准。
