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A.F. Cheng (Johns Hopkins Applied Phys Lab), D.E. Smith (NASA/GSFC), M.T. Zuber (MIT and NASA/GSFC), O. Barnouin-Jha (Johns Hopkins Applied Phys Lab)
The global shape model NLR393 has been determined from over 16 million ranges to the surface as measured by the NEAR Laser Rangefinder. The model is expressed as a spherical harmonic expansion of which the coefficients through degree and order 90 are used to create a plate model, where the surface is approximated with triangular planar facets (plates). The plate model analyzed here consists of 7722 plates, with a mean size (square root of mean area) of 380 m. The NLR393 shape model is consistent with an almost uniform density throughout the interior (Zuber et al., Science 289, 2097, 2000). With the density assumed constant, the gravitational-centrifugal potential is calculated at Eros's surface and used to determine elevation, as defined by the potential difference from the global mean value divided by the local acceleration of effective gravity. This elevation is an approximation to height above the geoid. A global topographic map of surface elevation, generated from NLR393, resolves craters smaller than 1 km and supports the interpretations of Himeros (saddle-shaped depression) and Shoemaker Regio (most boulder-rich area on Eros) as impact craters. The global distributions of slopes are characterized by two-point samples (pairs of points separated by baselines from 400 to 800 m) and three-point samples (slopes of triangular plates). Steep slopes are located preferentially on crater walls as noted by Zuber et al. The distributions of slopes are distinct from the distributions of roughness, as characterized by higher order samples and by fractal techniques.