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A.F. Cheng, O. Barnouin-Jha, L. Prockter, T. Cole, Y. Guo (JHU/APL), M.T. Zuber, G. Neumann (MIT), D.E. Smith, J. Garvin (NASA/GSFC), M. Robinson (Northwestern), J. Veverka, P. Thomas (Cornell)
The NEAR Laser Rangefinder (NLR) first detected Eros at a range of nearly 300 km and had accumulated, by mid-August 2000, over 7.6 million range returns from orbits as low as 35 km radius. We present the first results from analyses of altimetric profiles interpreted with the aid of simultaneous, boresighted images obtained by the NEAR Multispectral Imager (MSI). The location of the NLR boresight relative to that of MSI was determined by detailed correlations of ranging data and simultaneous images, including numerous cases where the laser boresight slewed off and on the limb of the asteroid, and one case where the laser illuminated a boulder at the same time it was imaged. In the data presented, the precision of the range measurements is about one meter, with the minimum spot diameter under 5 meters, and successive spots are contiguous or overlapping. We characterize the global fabric of ridges, grooves, and chains of craters or pits on Eros, and describe its regional variations. Surface roughness distributions and regional variations are also characterized. Peak-to-trough amplitudes of ridges and grooves southwest of the Psyche crater exceed 100 meters, but are under 40 meters toward the southeast of the saddle-shaped feature Himeros. The topographic profiles of the long ridge Rahe Dorsum are consistent with interpretation as a tectonic feature whose height reaches ~110 meters within Himeros. Several landslides, associated with steep slopes in crater walls, and crater benches are characterized. These data are used to infer a depth of loose regolith in the range 20 to 40 meters. Examples of jointed craters have been found. We suggest that many, and perhaps most, craters on Eros formed in a strength-controlled regime.