摘要
针对小行星天基光学监测中的可见性问题,基于辐射度传输理论,引入黄道光和银道光亮度模型,建立了小行星天基光学监测的信噪比模型。结合设计的可见光传感器和望远镜的性能参数,计算了目标小行星相对望远镜的信噪比和视星等随时间的变化;考虑极限信噪比和太阳规避角,计算了地球领航轨道可见光望远镜对不同直径小行星的极限监测距离;改变小行星的物理参数,研究了信噪比和视星等对小行星物理参数的敏感性。结果表明:目标小行星在给定的场景时间内相对望远镜距离增大了约0.09AU,视星等增大了约0.51,目标小行星在口径为0.7 m的望远镜中信噪比减小了约3.78;由于观测天区覆盖地球周围0.05AU的空间,在地球领航轨道部署可见光望远镜预警来自太阳方向的小行星具有明显的优势,能为直径20 m的小行星提供750万公里的预警距离;在可见光波段,小行星的信噪比和视星等对反照率敏感,对温度和发射率不敏感。所建立的小行星天基光学监测信噪比模型可为小行星天基光学监测的信噪比动态分析和预警距离评估提供理论依据。
To investigate asteroid visibility in space-based optical surveillance using the radiative transfer theory,a brightness model of zodiacal and galactic light was introduced,and a signal-to-noise ratio(SNR)model for space-based asteroid surveillance was established.Combining the designed visible sensor with telescope performance parameters,the SNR and apparent magnitude of the target asteroid relative to the telescope over time were simulated.By considering the minimum SNR and solar avoidance angle,the maximum surveillance distance of a visible telescope deployed on an Earth-leading heliocentric orbit for as⁃teroids of different diameters was calculated.The sensitivity of the SNR and apparent magnitude to the physical parameters of the asteroids was studied by changing the physical parameters of the asteroids.The results show that the distance of the asteroid relative to the telescope increased by approximately 0.09 AU,the apparent magnitude of the asteroid increased by approximately 0.51,and the SNR of the asteroid relative to a telescope with an aperture of 0.7 m decreased by approximately 3.78 during the period under observation.Owing to good coverage of the vicinity around the Earth with a radius of 0.05 AU,there is a unique advantage for visible telescopes deployed on Earth-leading heliocentric orbits to warn of asteroids approaching from the sunward direction;they can provide an early warning distance of 7.5 million km for asteroids with a diameter of 20 m.In the visible light band,the SNR and apparent magnitude of asteroids are sensitive to the visual albedo but not to the temperature and visual emissivity.The model established in this study provides a theoretical basis for the dynamic analysis of the SNR and the assessment of early warning distances for space-based optical surveillance of asteroids.
作者
王新涛
郑建华
李明涛
WANG Xin-tao;ZHENG Jian-hua;LI Ming-tao(National Space Science Center,Chinese Academy of Sciences,Beijing 101499,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《光学精密工程》
EI
CAS
CSCD
北大核心
2021年第12期2763-2773,共11页
Optics and Precision Engineering
基金
北京市重大科技专项资助项目(No.Z181100002918004)
空间科学预先研究项目(No.XDA1502030502,No.XDA15014900)。
关键词
空间光学
小行星天基监测
天空背景
可见光传感器
信噪比模型
视星等
space optics
space-based asteroid surveillance
zodiacal and galactic light
visible sensor
signal-to-noise ratio model
apparent magnitude
