Planets

Precise mass determination and the nature of Phobos

  1. T. P. Andert1,
  2. P. Rosenblatt2,
  3. M. Pätzold3,
  4. B. Häusler1,
  5. V. Dehant2,
  6. G. L. Tyler4,
  7. J. C. Marty5

Article first published online: 7 MAY 2010

DOI: 10.1029/2009GL041829

Issue

Geophysical Research Letters

Geophysical Research Letters

Additional Information

How to Cite

Andert, T. P., P. Rosenblatt, M. Pätzold, B. Häusler, V. Dehant, G. L. Tyler, and J. C. Marty (2010), Precise mass determination and the nature of Phobos, Geophys. Res. Lett., 37, L09202, doi:10.1029/2009GL041829.

Author Information

  1. 1

    Department of Space Technology, University of German Armed Forces, Munich, Germany

  2. 2

    Department of Reference Systems and Geodynamics, Royal Observatory of Belgium, Brussels, Belgium

  3. 3

    Department of Planetary Research, Rheinisches Institut für Umweltforschung, University of Cologne, Cologne, Germany

  4. 4

    Department of Electrical Engineering, Stanford University, Stanford, California, USA

  5. 5

    CNES, GRGS, Toulouse, France

Publication History

  1. Issue published online: 7 MAY 2010
  2. Article first published online: 7 MAY 2010
  3. Manuscript Accepted: 22 MAR 2010
  4. Manuscript Revised: 8 MAR 2010
  5. Manuscript Received: 3 DEC 2009

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Keywords:

  • Phobos;
  • Mars Express

[1] We report independent results from two subgroups of the Mars Express Radio Science (MaRS) team who independently analyzed Mars Express (MEX) radio tracking data for the purpose of determining consistently the gravitational attraction of the moon Phobos on the MEX spacecraft, and hence the mass of Phobos. New values for the gravitational parameter (GM = 0.7127 ± 0.0021 × 10−3 km3/s2) and density of Phobos (1876 ± 20 kg/m3) provide meaningful new constraints on the corresponding range of the body's porosity (30% ± 5%), provide a basis for improved interpretation of the internal structure. We conclude that the interior of Phobos likely contains large voids. When applied to various hypotheses bearing on the origin of Phobos, these results are inconsistent with the proposition that Phobos is a captured asteroid.

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