Surface water-ice deposits in the northern shadowed regions of Ceres

Abstract

Ceres, a dwarf planet located in the main asteroid belt, has a low bulk density1, and models predict that a substantial amount of water ice is present in its mantle and outer shell24. The Herschel telescope and the Dawn spacecraft5 have observed the release of water vapour from Ceres6,7, and exposed water ice has been detected by Dawn on its surface at mid-latitudes8. Water molecules from endogenic and exogenic sources can also be cold-trapped in permanent shadows at high latitudes911, as happens on the Moon12,13 and Mercury14,15. Here we present the first image-based survey of Ceres’s northern permanent shadows and report the discovery of bright deposits in cold traps. We identify a minimum of 634 permanently shadowed craters. Bright deposits are detected on the floors of just 10 of these craters in multi-scattered light. We spectroscopically identify one of the bright deposits as water ice. This detection strengthens the evidence that permanently shadowed areas have preserved water ice on airless planetary bodies.

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Figure 1: Composite binary-averaged mosaic of the north polar region of Ceres.
Figure 2: Craters hosting permanent shadows and bright deposits.
Figure 3: Craters hosting bright deposits.
Figure 4: Water-ice signatures within crater 2 in VIR spectra.

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Acknowledgements

We acknowledge the outstanding work of the Dawn design, engineering and operations team. We thank NASA, the Max Planck Society, and the German and Italian Space Agencies for support for this investigation.

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Contributions

T.P. designed the concept of this study, developed the threshold methodology, performed the image processing and prepared the manuscript. A.N., N.Scho., F.P., E.M., S.E.S., M.S., M.H., P.G.-M., W.D., J.R., K.-D.M. and C.T.R. contributed to the development of data analysis and interpretation. S.B. and M.E.L. performed the temperature calculations. Crater analysis and impact simulation were performed by T.K. and N.Schm., respectively. J.-P.C. and G.S.T. analysed the VIR data. All authors discussed and contributed to the preparation of this manuscript.

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Correspondence to T. Platz.

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The authors declare no competing financial interests.

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Supplementary Figures 1–8 with captions, Supplementary Table 1 with caption, captions for Supplementary Videos 1 and 2. (PDF 2318 kb)

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Platz, T., Nathues, A., Schorghofer, N. et al. Surface water-ice deposits in the northern shadowed regions of Ceres. Nat Astron 1, 0007 (2017). https://doi.org/10.1038/s41550-016-0007

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