[P-PS03] Small Solar System Bodies: New perspectives on the origin and evolution of the Solar System

[PPS03-P12] High Degree Products of Thermal Infrared Imager onboard Hayabusa2

*Takehiko Arai¹, Hirohide Demura², Tatsuaki Okada⁴, Satoshi Tanaka⁴, Naoya Sakatani⁴, Yuri Shimaki⁴, Hiroki Senshu³, Toru Kouyama⁵, Takuya Ishizaki⁴, Masanori Kanamaru⁷, Tomohiko Sekiguchi⁶ (1.Maebashi Institute of Technology, 2.The University of Aizu, 3.Chiba Institute of Technology, 4.Japan Aerospace Exploration Agency, 5.National Institute of Advanced Industrial Science and Technology, 6.Hokkaido University of Education, 7.The University of Tokyo)

Keywords:Hayabusa2, Thermal Infrared Imager, Thermal Inertia, High Degree Products

The thermal infrared imager (TIR) onboard the Hayabusa2 spacecraft observed the surface temperature of asteroid 162173 Ryugu during 2018 and 2019. TIR derives the surface thermophysical properties and reveals the surface thermal evolution and the origin of their accumulation process. Thermal inertia is a key index for estimating surface thermophysical properties. This index is critical for evaluating the surface's physical condition, such as density and porosity. However, surface roughness under the spatial resolution of TIR confuses the estimation of the thermal inertia. The observed surface brightness temperature of TIR was globally flattened due to the roughness. Therefore, we need a surface thermophysical model, including the roughness model, to derive the accurate thermal inertia. We used the shape model of Ryugu with Gaussian random numbers as the roughness model. We compared the observed image with the anticipated images derived from the thermophysical model with roughness and determined the thermal inertia maps. In this study, we introduce the high-degree products of the TIR data, such as shape model projection maps (Level 3) and thermal inertia maps (Level 4).