Phobos control point network, rotation, and shape

Abstract A new independent control point network for Phobos was computed from image data obtained by the SRC (Super Resolution Channel) on board the European Mars Express Mission. The network solution includes 3D coordinates of 665 surface control points and was used to observe the forced libration amplitude of Phobos. Based on the network control points a spherical harmonic function model to degree and order 17 was derived, from which volume, bulk density and moments of inertia were computed. The modeled forced libration amplitude agrees to our observation within the error bands, indicating a homogeneous mass distribution for Phobos. To bring both values into exact agreement with the observations, different mass distribution models were applied. It appears that the amplitude is relatively insensitive to a simple two-layer density model.

[1]  Thomas C. Duxbury,et al.  Phobos and Deimos control networks , 1989 .

[2]  M. Ya. Marov,et al.  Phobos-Grunt: Russian sample return mission , 2004 .

[3]  W. Baarda,et al.  A testing procedure for use in geodetic networks. , 1968 .

[4]  Thomas C. Duxbury,et al.  An analytic model for the Phobos surface , 1991 .

[5]  Dah-Ning Yuan,et al.  A global solution for the Mars static and seasonal gravity, Mars orientation, Phobos and Deimos masses, and Mars ephemeris , 2006 .

[6]  J. Oberst,et al.  New astrometric observations of Deimos with the SRC on Mars Express , 2008 .

[7]  R. Turner.  A model of Phobos , 1978 .

[8]  P. K. Seidelmann,et al.  Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2003 , 2005 .

[9]  Thomas C. Duxbury,et al.  The figure of Phobos , 1989 .

[10]  I. Shapiro,et al.  Arecibo radar observations of Phobos and Deimos , 2007 .

[11]  P. Thomas,et al.  Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites: 2000 , 2002 .

[12]  R. Jaumanna,et al.  The imaging performance of the SRC on Mars Express , 2008 .

[13]  L. H. Keith,et al.  Chemical and physical properties , 1992 .

[14]  Hauke Hussmann,et al.  New Astrometric Observations of Deimos with the SRC on Mars Express , 2011 .

[15]  M. S. Matthews,et al.  Resources of near-Earth space , 1993 .

[16]  D. Tholen,et al.  Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006 , 2007 .

[17]  J. Veverka,et al.  The generation and use of numerical shape models for irregular Solar System objects , 1993 .

[18]  Kenneth Seidelmann.  Working Group on Cartographic Coordinates and Rotational Elements , 2007 .

[19]  P. Thomas.  Shapes of small satellites , 1987 .

[20]  B. Fong Chao,et al.  The gravitational field of Phobos , 1989 .

[21]  W. Zeitler.  Simultane Neuausgleichung des globalen 3D-Mars-Netzes , 1999 .

[22]  C. F. Yoder,et al.  Phobos' gravity field and its influence on its orbit and physical librations , 1990 .