The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2

Abstract

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.

Modeling method and preliminary model of Asteroid Toutatis from Chang’E-2 optical images

“…It may be the result of a violent collision by two smaller bodies. According to the previous research [4], the maximum length in the image is about (4.75 ± 0.475) km. The maximum width is estimated about (1.95 ± 0.195) km.…”

“…When making a flyby, Chang'E-2 obtained more than 400 high-resolution images about Asteroid 4179 Toutatis [4]. The highest resolution is up to 3 m. The meteorite craters and terrain characters can be seen clearly.…”

“…In April 2012, Chang'E-2 departed from Earth-Sun L2 region to begin an extended mission to the Asteroid 4179 Toutatis, and made a successful flyby in December 2012. The closest distance is about (770±120) m, and the relative velocity is about 10.73 km/s [4]. During the flyby, Chang'E-2 obtained plenty of high-resolution optical images [5,6].…”

Using Chebyshev polynomial interpolation to improve the computational efficiency of gravity models near an irregularly-shaped asteroid

“…Since the first close-up image of asteroid 951 Gaspra taken in 1971 by Galileo spacecraft en route to Jupiter, 13 asteroids (including dwarf planet Ceres and Pluto) have been explored by spacecrafts. On December 13, 2012, the Chinese lunar probe Chang'e-2 flew by Toutatis with a surface distance of 0.77 km (Huang et al 2013;Jiang et al 2015;Zhao et al 2015). Recently, OSIRIS-REx was launched by NASA on September 8, 2016 and now is on its way to asteroid 101955 Bennu (Lauretta and Team 2012).…”

“…Asteroid 4179 Toutatis is a typical irregular-shaped asteroid, with dimension x = 4.60 km, y = 2.29 km and z = 1.92 km (Hudson et al 2003;Huang et al 2013). Take Toutatis as example, the division is illustrated in Fig.…”