[M-ZZ45] Planetary defense - what should we do?

[MZZ45-P05] Development of Orbit Prediction Model Based on Asteroid Thermography

*Masanori Kanamaru¹, Giacomo Tommei², Tatsuaki Okada³, Naoya Sakatani³, Yuri Shimaki³, Satoshi Tanaka³, Takuya Ishizaki³, Hiroki Senshu⁴, Takehiko Arai⁵, Tomohiko Sekiguchi⁶, Naru Hirata⁷, Hirohide Demura⁷, Seiji Sugita¹ (1.The University of Tokyo, 2.The University of Pisa, 3.ISAS/JAXA, 4.Chiba Institute of Technology, 5.Maebashi Institute of Technology, 6.Hokkaido University of Education, 7.The University of Aizu)

Keywords:Asteroid, Thermophysical model, Non-gravitational acceleration

Thermophysical simulation of an asteroid is beneficial not only for preliminary investigation of observation conditions for a spacecraft and a rover and comparison with infrared observations but also for prediction of non-gravitational effects acting on the asteroid, such as the Yarkovsky effect and YORP effect. These effects cause perturbations in the orbit and rotation of the asteroid. In order to precisely predict the orbit of the asteroid approaching the earth, it is necessary to improve the model of non-gravitational effects based on thermal observations of asteroids.

We have been developing a numerical simulator for the dynamical evolution of asteroids, "Astroshaper". The thermophysical model implemented in Astroshaper will be compared with thermal observations conducted by the Hayabusa2 and Hera missions to determine the thermal properties of asteroids and to estimate non-gravitational effects. Using the shape model derived from ground-based observations, we calculated the BYORP (binary YORP) effect acting on the binary asteroid Didymos and its satellite Dimorphos. It was found that the BYORP effect could work to broaden the mutual orbits of the Dimorphos. The accuracy of the prediction should be improved by using the high-resolution shape model obtained by the Hera mission. In the future, we plan to apply the improved thermophysical model based on the findings from the Hayabusa2 and Hera missions to predict an orbit of a potentially hazardous asteroid.