Revisit of rotational dynamics of Asteroid 4179 Toutatis from Chang'e-2's flyby

TL;DR

This study analyzes the rotational dynamics of asteroid Toutatis using Chang'e-2 flyby data, revealing its tumbling motion, specific Euler angles, and rotational periods, enhancing understanding of its rotational state.

Contribution

It provides a detailed analysis of Toutatis' rotational parameters from flyby data, including Euler angles and rotational periods, which were not previously well-characterized.

Findings

Euler angles at flyby: -20.1°, 27.6°, 42.2°

Rotational period about long axis: 5.38 days

Precession period: 7.40 days

Abstract

This paper presents analysis of the rotational parameters of Toutatis based on the observational results from Chang'e-2's close flyby. The 3-D shape model derived from ground-based radar observation is used to calculate the 3-1-3 Euler angles at the flyby epoch, which are evaluated to be $-20.1^\circ\pm1^\circ$, $27.6^\circ\pm1^\circ$ and $42.2^\circ\pm1^\circ$. The large amplitude of Toutatis' tumbling attitude is demonstrated to be the result of the large deviation of the angular momentum axis and the rotational axis. Two rotational periods are evaluated to be $5.38\pm0.03$ days for rotation about the long axis and $7.40\pm0.03$ days for precession of the long axis about the angular momentum vector based on Fourier analysis. These results provide a further understanding of rotational state of Toutatis.