Introduction to the Special Issue: Ice on Ceres. Issue 7 (16th July 2019)

• Record Type: Journal Article
• Authors: Sizemore, H. G.; Schmidt, B. E.; Castillo‐Rogez, J. C.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 7(2019)
• Page Start: 1639
• Page End: 1649
• Publication Date: 2019-07-16
• Subjects: Ceres -- ice -- cryosphere -- asteroid belt; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2019JE006012
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: Ceres is the largest body in the asteroid belt, and the most water‐rich inner solar system body after Earth. Its exploration by the Dawn spacecraft has been long anticipated, in large part because it was expected to be an ice‐rich world. A variety of ice‐ and volatile‐related physical processes were expected to occur on Ceres, including possible cryovolcanism. A major goal of the Dawn mission at Ceres was to understand the abundance, distribution, and phase partitioning of water in the subsurface. Coordinated investigations of subsurface ice during the Dawn mission benefited from the decades‐long effort to inventory and characterize subsurface ice on Mars. Specifically, morphological analysis was leveraged to bridge a length‐scale gap between geophysical remote sensing data sets that provide quantitative constraints on the abundance of subsurface ice at very shallow depths (<1 m; neutron spectroscopy) and data sets that provide quantitative constraints on composition at much longer length scales (tens of kilometers; gravity science). This morphological analysis underscores that Ceres shares geophysical characteristics with terrestrial planets, icy moons, comets, and asteroids, and blurs some of the conventional boundaries between these terms. Grappling with this ambiguity stands to benefit investigations of interior evolution and volatile‐related processes on all solid planetary bodies. Plain Language Summary: Dwarf planet Ceres, the largest object in the main asteroid belt, was known to have a water‐rich interior and to episodically outgas water vapor to space when the Dawn spacecraft arrived at Ceres in 2015. Dawn performed global mapping of Ceres' elemental and mineralogical composition, geology, and subsurface structure. Analysis of the Dawn data sets has leveraged frameworks and techniques developed for characterizing the abundance and distribution of ice on Mars. Collectively, these investigations indicate that ice and water played key roles in shaping the dwarf planet. They have revealed Ceres to be a complex object that shares characteristics with many different types of solar system objects, including terrestrial planets, icy moons, comets, and asteroids. Key Points: Investigations of ice at Ceres have long been anticipated due to the importance of water in driving its chemical and physical evolution Investigations of subsurface ice at Ceres benefited from the decades‐long effort to inventory and characterize subsurface ice on Mars Ceres blurs conventional boundaries, sharing characteristics with terrestrial planets, icy moons, comets, and asteroids