# 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 3-dimensional shape model of Phobos by Duxbury, the gravitational coefficients up to degree and order 4 for a homogeneous Phobos are computed. In particular, the authors find J{sub 2} = 0.105. The in-plane liberation amplitude of a homogeneous Phobos is predicted to be 0.97{degree}, within the rather large uncertainty of the observed value of 0.78 {plus minus} 0.4{degree}.

- Authors:

- (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

- Publication Date:

- OSTI Identifier:
- 5833124

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Geophysical Research Letters (American Geophysical Union); (USA); Journal Volume: 16:8

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MARS PLANET; SATELLITES; GRAVITATIONAL FIELDS; CALCULATION METHODS; CARTESIAN COORDINATES; DENSITY; MORPHOLOGY; SPHERICAL HARMONICS; TOPOGRAPHY; COORDINATES; PHYSICAL PROPERTIES; PLANETS; 640107* - Astrophysics & Cosmology- Planetary Phenomena

### Citation Formats

```
Chao, B.F., and Rubincam, D.P.
```*The gravitational field of Phobos*. United States: N. p., 1989.
Web. doi:10.1029/GL016i008p00859.

```
Chao, B.F., & Rubincam, D.P.
```*The gravitational field of Phobos*. United States. doi:10.1029/GL016i008p00859.

```
Chao, B.F., and Rubincam, D.P. Tue .
"The gravitational field of Phobos". United States.
doi:10.1029/GL016i008p00859.
```

```
@article{osti_5833124,
```

title = {The gravitational field of Phobos},

author = {Chao, B.F. and Rubincam, D.P.},

abstractNote = {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 3-dimensional shape model of Phobos by Duxbury, the gravitational coefficients up to degree and order 4 for a homogeneous Phobos are computed. In particular, the authors find J{sub 2} = 0.105. The in-plane liberation amplitude of a homogeneous Phobos is predicted to be 0.97{degree}, within the rather large uncertainty of the observed value of 0.78 {plus minus} 0.4{degree}.},

doi = {10.1029/GL016i008p00859},

journal = {Geophysical Research Letters (American Geophysical Union); (USA)},

number = ,

volume = 16:8,

place = {United States},

year = {Tue Aug 01 00:00:00 EDT 1989},

month = {Tue Aug 01 00:00:00 EDT 1989}

}

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