Conditions for Sublimating Water Ice to Supply Ceres' Exosphere

M. E. Landis, S. Byrne, N. Schörghofer, B. E. Schmidt, P. O. Hayne, J. Castillo-Rogez, M. V. Sykes, J. P. Combe, A. I. Ermakov, T. H. Prettyman, C. A. Raymond, C. T. Russell

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Observations of a water vapor exosphere around Ceres suggest that the dwarf planet may be episodically outgassing at a rate of ~6 kg s−1 from unknown sources. With data from the Dawn mission as constraints, we use a coupled thermal and vapor diffusion model to explore three different configurations of water ice (global buried pore-filling ice, global buried excess ice, and local exposed surface ice) that could be present on Ceres. We conclude that a buried ice table cannot alone explain the vapor production rates previously measured, but newly exposed surface ice, given the right conditions, can exceed that vapor production rate. Sublimation lag deposits form that bury and darken this surface ice over a large range of timescales (from <1 year to approximately hundreds of kyr) that depend on latitude and ice regolith content. Sublimating water vapor can loft regolith particles from the surface of exposed ice, possibly prolonging the visible lifespan of those areas. We find that this process is only effective for regolith grains smaller than approximately ones of microns.

Original languageEnglish (US)
Pages (from-to)1984-1995
Number of pages12
JournalJournal of Geophysical Research: Planets
Volume122
Issue number10
DOIs
StatePublished - Oct 2017

Keywords

  • Ceres
  • exosphere
  • ice

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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