[U-06_28AM1] New Progress toward the Understanding of Small Solar System Bodies

[U06-P11_PG] Cratering chronology models for the near-Earth asteroid 1999 JU3

3-min talk in an oral session

*Kosuke ANDO¹, Tomokatsu MOROTA¹, Seiji SUGITA², Rie HONDA³, Shingo KAMEDA⁴, Manabu YAMADA⁵, Chikatoshi HONDA⁶, Hidehiko SUZUKI⁴, Sei-ichiro WATANABE⁷ (1.Graduate School of Environmental Studies, Nagoya University, 2.Department of Complexity Science and Engineering, Graduate School of Frontier Sciece, The University, 3.Departmant of information Sciemce, Kochi University, 4.School of Science, Rikkyo University, 5.Planetary Exploration Research Center, Chiba Institute of Technology, 6.The University of Aizu, 7.Division of Earth and Planetary Sciences, Graduate School of Science, Nagoya University)

The Japanese asteroid explorer Hayabusa-2, that is scheduled for launch in 2014, will be observe a near Earth C-type asteroid 1999 JU3 and will return to Earth with its samples. In this study, we model cratering and crater erasure processes on 1999 JU3 to provide an age estimate for 1999 JU3 based on high-resolution images that will be obtained by Hayabusa-2. The impact rate on 1999 JU3 is calculated from population models of main-belt asteroids (MBAs) and near-Earth asteroids (NEAs) and the average collision probabilities for the main belt and for NEAs. By converting the impactor size to the size of consequent crater based on crater scaling law and the average collision velosities for the main belt and for NEAs, the cratering rate on 1999 JU3 is calculated. For comparison, we use two population models of asteroids, two crater scaling laws and five conditions of surface of 1999JU3. In addition, two crater erasure processes, seismic shaking and saturation of craters, are considered in our model. As a result, our models indicate that age estimate of 1999 JU3 primary depends on crater scaling laws used and assumptions of surface conditions of 1999 JU3 rather than population models of asteroids.