On 13 December 2012, Chang'e-2 conducted a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 ± 120 meters from the asteroid's surface. The highest-resolution image, with a resolution of better than 3 meters, reveals new discoveries on the asteroid, e.g., a giant basin at the big end, a sharply perpendicular silhouette near the neck region, and direct evidence of boulders and regolith, which suggests that Toutatis may bear a rubble-pile structure. Toutatis' maximum physical length and width are (4.75 × 1.95 km) ±10%, respectively, and the direction of the +z axis is estimated to be (250±5∘, 63±5∘) with respect to the J2000 ecliptic coordinate system. The bifurcated configuration is indicative of a contact binary origin for Toutatis, which is composed of two lobes (head and body). Chang'e-2 observations have significantly improved our understanding of the characteristics, formation, and evolution of asteroids in general.
@article{arxiv.1312.4329,
title = {The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2},
author = {Jiangchuan Huang and Jianghui Ji and Peijian Ye and Xiaolei Wang and Jun Yan and Linzhi Meng and Su Wang and Chunlai Li and Yuan Li and Dong Qiao and Wei Zhao and Yuhui Zhao and Tingxin Zhang and Peng Liu and Yun Jiang and Wei Rao and Sheng Li and Changning Huang and Wing-Huen Ip and Shoucun Hu and Menghua Zhu and Liangliang Yu and Yongliao Zou and Xianglong Tang and Jianyang Li and Haibin Zhao and Hao Huang and Xiaojun Jiang and Jinming Bai},
journal= {arXiv preprint arXiv:1312.4329},
year = {2019}
}