Exploring Exogenic Sources for the Olivine on Asteroid (4) Vesta

Abstract

The detection of olivine on Vesta is interesting because it may provide critical insights into planetary differentiation early in our Solar System's history. Ground-based and Hubble Space Telescope (HST) observations of asteroid (4) Vesta have suggested the presence of olivine on the surface. These observations were reinforced by the discovery of olivine-rich HED meteorites from Vesta in recent years. However, analysis of data from NASA's Dawn spacecraft has shown that this olivine-bearing unit is actually impact melt in the ejecta of Oppia crater. The lack of widespread mantle olivine, exposed during the formation of the 19 km deep Rheasilvia basin on Vesta's South Pole, further complicated this picture. Ammannito et al., (2013a) reported the discovery of local scale olivine-rich units in the form of excavated material from the mantle using the Visible and InfraRed spectrometer (VIR) on Dawn. Here we explore alternative sources for the olivine in the northern hemisphere of Vesta by reanalyzing the data from the VIR instrument using laboratory spectral measurements of meteorites. We suggest that these olivine exposures could be explained by the delivery of olivine-rich exogenic material. Based on our spectral band parameters analysis, the lack of correlation between the location of these olivine-rich terrains and possible mantle-excavating events, and supported by observations of HED meteorites, we propose that a probable source for olivine seen in the northern hemisphere are remnants of impactors made of olivine-rich meteorites. Best match suggests these units are HED material mixed with either ordinary chondrites, or with some olivine-dominated meteorites such as R-chondrites.

arXiv comment62 pages, 12 figures, 4 tables; Icarus, Available online 30 January 2015, ISSN 0019-1035, http://dx.doi.org/10.1016/j.icarus.2015.01.018

References in corpus (9)

• Phase reddening on near-Earth asteroids: Implications for mineralogical analysis, space weathering and taxonomic classification
• Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts
• Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family
• Physical Characterization of Warm Spitzer-observed Near-Earth Objects
• Olivine-dominated asteroids: Mineralogy and origin
• Olivine or Impact Melt: Nature of the "Orange" Material on Vesta from Dawn
• Comparing Dawn, Hubble Space Telescope, and Ground-Based Interpretations of (4) Vesta
• The contamination of the surface of Vesta by impacts and the delivery of the dark material
• Olivine-rich exposures at Bellicia and Arruntia craters on (4) Vesta from Dawn FC

Cited by in corpus (8)

• The Sariçiçek howardite fall in Turkey: Source crater of HED meteorites on Vesta and impact risk of Vestoids
• Ground-based Characterization of Hayabusa2 Mission Target Asteroid 162173 Ryugu: Constraining Mineralogical Composition in Preparation for Spacecraft Operations
• Olivine on Vesta as exogenous contaminants brought by impacts: Constraints from modeling Vesta's collisional history and from impact simulations
• Vestoids, Part II: The basaltic nature and HED meteorite analogs for eight Vp-type asteroids and their associations with (4) Vesta
• Characterization of Exogenic Boulders on Near-Earth Asteroid (101955) Bennu from OSIRIS-REx Color Images
• The Physical Characterization of the Potentially-Hazardous Asteroid 2004 BL86: A Fragment of a Differentiated Asteroid
• Three-dimensional spectral analysis of compositional heterogeneity at Arruntia crater on (4) Vesta using Dawn FC
• Spectral Deconvolution Analysis on Olivine-Orthopyroxene Mixtures with Simulated Space Weathering Modifications