Geometric correction for thermographic images of asteroid 162173 Ryugu by TIR (thermal infrared imager) onboard Hayabusa2
Geometric correction for thermographic images of asteroid 162173 Ryugu by TIR (thermal infrared imager) onboard Hayabusa2
复制标题
隼鸟二号上的 TIR（热红外成像仪）对小行星 162173 Ryugu 的热成像图像进行几何校正
DOI：
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Yukio Yamamoto
中科院分区：
文献类型：
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作者：
T. Arai;T. Okada;Satoshi Tanaka;T. Fukuhara;H. Demura;T. Kouyama;N. Sakatani;Y. Shimaki;H. Senshu;T. Sekiguchi;J. Takita;N. Hirata;Yukio Yamamoto
从2018年6月到2019年11月，Hayabusa2号航天器上的热红外成像仪对小行星162173龙(1999 JU$$3$3)进行了热成像观测。我们之前的报告显示，琉球的表面充满了多孔材料，具有很高的表面粗糙度。这些结果是通过将观测到的TIR温度图投影到Ryugu形状模型上作为几何校正而得到的。在光学导航相机(ONC)和光探测和测距(LIDAR)观测期间，利用SPICE核(NASA/NAIF)的数据内插计算了TIR的指向方向。然而，当不使用TIR进行ONC和LIDAR时，观测到的TIR图像的映射精度降低。此外，Hayabusa2的轨道和高度起伏也增加了温度图的误差。为了解决温度图像的映射问题，我们改进了TIR图像的校正方法，将所有观测到的TIR图像与琉球高清晰度形状模型(SFM 800k V20180804)上的表面坐标进行了拟合。此校正通过使用最小二乘拟合相对于Hayabusa2帧旋转TIR帧来调整TIR的指向方向。结果，温度图在高分辨率的$0.5^CIRC$0内收敛到空间扩展区域。5∘by$$0.5^CIRC$$0。5个∘地图。例如，在额济马萨克逊热区，估算的热惯量约为300$$SIM$$∼350JM$$^-2 S$$^-0.5}$-0.5K$$-1。在地表地貌特征大于TIR像元尺度的情况下，该估计是成功的。然而，由于地表粗糙度的影响，如Urashima陨石坑等光滑地形的热惯量估计很困难，那里的粗糙度可能比TIR的像素尺度小得多。
The thermal infrared imager (TIR) onboard the Hayabusa2 spacecraft performed thermographic observations of the asteroid 162173 Ryugu (1999 JU $$_3$$ 3 ) from June 2018 to November 2019. Our previous reports revealed that the surface of Ryugu was globally filled with porous materials and had high surface roughness. These results were derived from making the observed temperature maps of TIR using a projection method onto the shape model of Ryugu as geometric corrections. The pointing directions of TIR were calculated using an interpolation of data from the SPICE kernels (NASA/NAIF) during the periods when the optical navigation camera (ONC) and the light detection and ranging (LIDAR) observations were performed. However, the mapping accuracy of the observed TIR images was degraded when the ONC and LIDAR were not performed with TIR. Also, the orbital and attitudinal fluctuations of Hayabusa2 increased the error of the temperature maps. In this paper, to solve the temperature image mapping problems, we improved the correction method by fitting all of the observed TIR images with the surface coordinate addressed on the high-definition shape model of Ryugu (SFM 800k v20180804). This correction adjusted the pointing direction of TIR by rotating the TIR frame relative to the Hayabusa2 frame using a least squares fit. As a result, the temperature maps spatially spreading areas were converged within high-resolved $$0.5^circ$$ 0 . 5 ∘ by $$0.5^circ$$ 0 . 5 ∘ maps. The estimated thermal inertia, for instance, was approximately 300 $$sim$$ ∼ 350 Jm $$^{-2}$$ - 2 s $$^{-0.5}$$ - 0.5 K $$^{-1}$$ - 1 at the hot area of the Ejima Saxum. This estimation was succeeded in case that the surface topographic features were larger than the pixel scale of TIR. However, the thermal inertia estimation of smooth terrains, such as the Urashima crater, was difficult because of surface roughness effects, where roughness was probably much smaller than the pixel scale of TIR.
隼鸟二号热红外成像仪对地月观测及其在小行星162173龙宫探测中的应用
影响因子：
2.4
作者：
Okada T
通讯作者：
Okada T