Radius and limb topography of Mercury obtained from images acquired during the MESSENGER flybys |
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| Authors: | Jürgen Oberst Stephan Elgner F Scott Turner Mark E Perry Robert W Gaskell Maria T Zuber Mark S Robinson Sean C Solomon |
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| Institution: | aGerman Aerospace Center, Institute of Planetary Research, Rutherfordstr. 2, D-12489 Berlin, Germany;bJohns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA;cPlanetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719, USA;dDepartment of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;eSchool of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA;fDepartment of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA |
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| Abstract: | Analysis of images obtained by the MESSENGER spacecraft during its three flybys of Mercury yields a new estimate for the planet's mean radius of 2439.25±0.69 km, in agreement with results from Mariner 10 and Earth-based observations, as well as with MESSENGER altimeter and occultation data. The mean equatorial radius and polar radius are identical to within error, suggesting that rotational oblateness is negligible when compared with other sources of topography. This result is consistent with the small gravitational oblateness of the planet. Minor differences in radius obtained at different locations reflect regional variations in topography. Residual topography along three limb profiles has a dynamic range of 7.4 km and a root-mean-square roughness of 0.8 km over hemispherical scales. Following MESSENGER's entry into orbit about Mercury in March 2011, we expect considerable additional improvements to our knowledge of Mercury's size and shape. |
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| Keywords: | Mercury Radius Topography Imaging MESSENGER |
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