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Science 12 January 1996:
Vol. 271. no. 5246, pp. 184 - 188
DOI: 10.1126/science.271.5246.184
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Reports

The Shape of Mars and the Topographic Signature of the Hemispheric Dichotomy

David E. Smith and Maria T. Zuber

Reanalysis of occultation data from the Mariner 9 and Viking Orbiter spacecraft to determine the shape of Mars indicated that the hemispheric dichotomy is not a fundamental feature of the shape of the planet. It is a consequence of an approximately 3-kilometer offset between Mars's center of mass and center of figure, and the boundary, along most of its length, consists of broad, gradual surface slopes over distances of thousands of kilometers. This result was supported by analysis of high spatial resolution Earth-based radar topographic profiles. Any successful model for the origin of the dichotomy must explain a planet with an ellipsoidal shape and a long wavelength gradual topographic transition between the northern and southern hemispheres.


D. E. Smith, Laboratory for Terrestrial Physics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.
M. T. Zuber, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA, and Laboratory for Terrestrial Physics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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D. E. Smith, M. T. Zuber, and G. A. Neumann (2001)
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Internal Structure and Early Thermal Evolution of Mars from Mars Global Surveyor Topography and Gravity.
M. T. Zuber, S. C. Solomon, R. J. Phillips, D. E. Smith, G. L. Tyler, O. Aharonson, G. Balmino, W. B. Banerdt, J. W. Head, C. L. Johnson, et al. (2000)
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The Global Topography of Mars and Implications for Surface Evolution.
D. E. Smith, M. T. Zuber, S. C. Solomon, R. J. Phillips, J. W. Head, J. B. Garvin, W. B. Banerdt, D. O. Muhleman, G. H. Pettengill, G. A. Neumann, et al. (1999)
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The Structure of the Upper Atmosphere of Mars: In Situ Accelerometer Measurements from Mars Global Surveyor.
G. M. Keating, S. W. Bougher, R. W. Zurek, R. H. Tolson, G. J. Cancro, S. N. Noll, J. S. Parker, T. J. Schellenberg, R. W. Shane, B. L. Wilkerson, et al. (1998)
Science 279, 1672-1676
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Topography of the Northern Hemisphere of Mars from the Mars Orbiter Laser Altimeter.
D. E. Smith, M. T. Zuber, H. V. Frey, J. B. Garvin, J. W. Head, D. O. Muhleman, G. H. Pettengill, R. J. Phillips, S. C. Solomon, H. J. Zwally, et al. (1998)
Science 279, 1686-1692
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