P42A-04
Ceres in Color: Surface variegation suggests a compositionally diverse landscape
Thursday, 17 December 2015: 11:05
2007 (Moscone West)
Vishnu Reddy1, Andreas Nathues2, Lucille Le Corre1, Edward Cloutis3, Matthew R Izawa4, Martin Hoffmann2, Michael Schäfer2, Thomas Platz2, Guneshwar Thangjam2, Carle M Pieters5, Lucy A McFadden6, Britney E Schmidt7, Harry Y McSween Jr8 and Dawn Science Team, (1)Planetary Science Institute Tucson, Tucson, AZ, United States, (2)Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, (3)University of Winnipeg, Department of Geography, Winnipeg, MB, Canada, (4)University of Western Ontario, London, ON, Canada, (5)Brown University, Earth, Environmental and Planetary Sciences, Providence, RI, United States, (6)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (7)Georgia Institute of Technology Main Campus, Atlanta, GA, United States, (8)University of Tennessee, Knoxville, TN, United States
Abstract:
NASA’s Dawn spacecraft entered orbit around dwarf planet Ceres in March 2015 to begin a yearlong exploration. The Framing Cameras (FC) onboard Dawn are mapping the surface of Ceres with seven color filters (0.4-1.0 microns) and one clear panchromatic filter. These data provide unprecedented information at high spatial resolution. During its exploration of Vesta, Dawn’s first target, several distinct compositional units were observed in the FC color data. Like Vesta, Ceres exhibits hemispherical dichotomy with the Eastern hemisphere being brighter than the Western hemisphere. In the Eastern hemisphere there appears to be an old impact basin between ~80 and 170 deg E longitude containing the craters Kerwan and Dantu. This old basin seems to have excavated bright material that dominates the hemisphere. Ceres background material has a geometric albedo ranging from 0.09 to 0.11 but the albedo of the small bright spots is much higher, ranging between 0.2 and 0.4. In addition, Dawn FC observed several surface units of intermediate albedo hinting at compositionally distinct surface material. Areas with geometric albedo lower than Ceres average are primarily associated with ejecta blankets of impact craters such as Occator and could either represent material darkened by impact melting, or material mixed with an exogenic component from remnant material of the impactor. A majority of the small bright spots on Ceres are located on the walls, floors or ejecta blankets of impact craters and could represent excavated material from a sub-surface layer. Based on the albedo and colors obtained from Dawn FC, we have identified several units on the surface of Ceres. These include bright spots, dark material, and average Cerean surface material. Color spectra of these different units show a UV drop-off and varying spectral slope. With higher resolution images now being acquired we expect to find more clues revealing their formation mechanism and also detect smaller-scale color units with distinct compositional characteristics.
