The gravitational field of Phobos
Abstract
The external gravitational field produced by a rigid body of uniform density but irregular shape is formulated in terms of spherical harmonics. The formalism is applied to the Martian satellite Phobos. Based on a 3dimensional shape model of Phobos by Duxbury, the gravitational coefficients up to degree and order 4 for a homogeneous Phobos are computed. In particular, we find J_{2} = 0.105. The inplane libration amplitude of a homogeneous Phobos is predicted to be 0.97°, within the rather large uncertainty of the observed value of 0.78 ± 0.4°.
 Publication:

Geophysical Research Letters
 Pub Date:
 August 1989
 DOI:
 10.1029/GL016i008p00859
 Bibcode:
 1989GeoRL..16..859C
 Keywords:

 Gravitational Fields;
 Phobos;
 Planetary Gravitation;
 Satellite Imagery;
 Topography;
 Natural Satellites;
 Numerical Analysis;
 Viking Spacecraft;
 MARS;
 SATELLITES;
 PHOBOS;
 GRAVITY FIELDS;
 HARMONICS;
 DENSITY;
 PARAMETERS;
 SHAPE;
 CALCULATIONS;
 Lunar and Planetary Exploration; Satellites of Mars;
 Planetology: Solid Surface Planets and Satellites: Gravitational fields;
 Geodesy and Gravity: Geopotential theory and determination;
 Planetology: Solid Surface Planets and Satellites: Orbital and rotational dynamics;
 Planetology: Comets and Small Bodies: Gravitational fields