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Post by Chicago Astronomer Joe on Oct 11, 2006 21:59:09 GMT -6
Near Infrared Mapping Of Ceres Surface
Although Ceres is the largest main-belt asteroid and was the first to be discovered (by G.Piazzi in 1801), its physical properties are still not well understood. While it is expected to have retained a large amount of primordial water ice in its interior, many questions about the composition of its surface and sub-surface layers, the properties of its regolith, its degree of differentiation, etc, remain unanswered.
We used state-of-the-art adaptive optics instrumentation available at the Keck observatory, Mauna Kea, Hawaii, to image the surface of Ceres with a spatial resolution of 30km. Our observations were carried out during the 2002 opposition of Ceres in the near-infrared J/H/K-bands, at a wavelength range particularly well adapted to investigate the composition and properties of planetary surfaces.
We produced albedo maps covering 80% of the asteroid, which appears to display a wealth of 40 to 160km large geological features with intensity in reflected light varying by 12% across the surface (see attachment). We believe that these variations could be due to particular terrain features, as well as differences in their surface composition and/or degree of alteration by space weathering effects (ageing of surface due to interaction of solar wind, micrometeorites impacts, etc).