Rotational motion of Phobos

• Published in: Astronomy and astrophysics (Berlin) Vol. 548; p. 1
• Main Authors: Rambaux, N, Castillo-Rogez, J C, Le Maistre, S, Rosenblatt, P
• Format: Journal Article
• Language: English
• Published: 01.12.2012
• ISSN: 0004-6361; 1432-0746

The objective of this paper is to present the spectrum of Phobos' librations by using recent orbital ephemerides and geophysical knowledge of this Martian satellite. The analysis of the librational spectrum highlights the relationship between dynamical and geophysical properties of the body, but is also useful for cartographic and geodetic purposes for future space missions dedicated to Phobos. The authors developed a numerical model of Phobos' rotation that includes the point-mass Mars acting on the dynamical shape of Phobos, expanded to the third degree, and the effect of Mars' oblateness. Phobos exhibits a rich and varied set of librational oscillations. The main librations and the librations close to the proper frequencies are the most sensitive to the interior structure. On the other hand, the superimposed effect of large amplitude oscillations is likely to make the determination of the mean obliquity challenging.