Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts

Abstract

NASA's Dawn spacecraft observations of asteroid (4) Vesta reveal a surface with the highest albedo and color variation of any asteroid we have observed so far. Terrains rich in low albedo dark material (DM) have been identified using Dawn Framing Camera (FC) 0.75 μm filter images in several geologic settings: associated with impact craters (in the ejecta blanket material and/or on the crater walls and rims); as flow-like deposits or rays commonly associated with topographic highs; and as dark spots (likely secondary impacts) nearby impact craters. This DM could be a relic of ancient volcanic activity or exogenic in origin. We report that the majority of the spectra of DM are similar to carbonaceous chondrite meteorites mixed with materials indigenous to Vesta. Using high-resolution seven color images we compared DM color properties (albedo, band depth) with laboratory measurements of possible analog materials. Band depth and albedo of DM are identical to those of carbonaceous chondrite xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance in DM (1-6 vol%) is consistent with howardite meteorites. We find no evidence for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of DM. Our modeling efforts using impact crater scaling laws and numerical models of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta during the formation of the ~400 km Veneneia basin by a low-velocity (<2 km/sec) carbonaceous impactor. This discovery is important because it strengthens the long-held idea that primitive bodies are the source of carbon and probably volatiles in the early Solar System.

Icarus (Accepted) Pages: 58 Figures: 15 Tables: 2

References in corpus (1)

• Cometary Origin of the Zodiacal Cloud and Carbonaceous Micrometeorites

Cited by in corpus (39)

• Resolved Spectrophotometric Properties of the Ceres Surface from Dawn Framing Camera Images
• Global Photometric Properties of Asteroid (4) Vesta Observed with Dawn Framing Camera
• Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family
• Connecting Asteroids and Meteorites with visible and near-infrared spectroscopy
• Mineralogy and Surface Composition of Asteroids
• Different origins or different evolutions? Decoding the spectral diversity among C-type asteroids
• (16) Psyche: A mesosiderite-like asteroid?
• Detection of Water and/or Hydroxyl on Asteroid (16) Psyche
• Olivine or Impact Melt: Nature of the "Orange" Material on Vesta from Dawn
• Asteroid 16 Psyche: Shape, Features, and Global Map
• Mars Encounters cause fresh surfaces on some near-Earth asteroids
• Astronomical Observations of Volatiles on Asteroids
• Detection of Rotational Spectral Variation on the M-type asteroid (16) Psyche
• Comparing Dawn, Hubble Space Telescope, and Ground-Based Interpretations of (4) Vesta
• Exploring Exogenic Sources for the Olivine on Asteroid (4) Vesta
• The contamination of the surface of Vesta by impacts and the delivery of the dark material
• Asteroid Photometry
• Evidence for OH or H2O on the surface of 433 Eros and 1036 Ganymed
• More chips off of Asteroid (4) Vesta: characterization of eight Vestoids and their HED meteorite analogs
• Lithologic Mapping of HED Terrains on Vesta using Dawn Framing Camera Color Data
• The Heterogeneous Surface of Asteroid (16) Psyche
• The boulder population of asteroid 4 Vesta: Size-frequency distribution and survival time
• Ground-based Characterization of Hayabusa2 Mission Target Asteroid 162173 Ryugu: Constraining Mineralogical Composition in Preparation for Spacecraft Operations
• Survival of the impactor during hypervelocity collisions I: An analogue for low porosity targets
• The Formation of Jupiter, the Jovian Early Bombardment and the Delivery of Water to the Asteroid Belt: The Case of (4) Vesta
• Basalt or not? Near-infrared spectra, surface mineralogical estimates, and meteorite analogs for 33 Vp-type asteroids
• Olivine on Vesta as exogenous contaminants brought by impacts: Constraints from modeling Vesta's collisional history and from impact simulations
• Survival of the impactor during hypervelocity collisions II: An analogue for high porosity targets
• Constraining the Regolith Composition of Asteroid (16) Psyche via Laboratory Near-infrared Spectroscopy
• Dielectric Properties of Vesta's Surface as Constrained by Dawn VIR Observations
• Link between the Potentially Hazardous Asteroid (86039) 1999 NC43 and the Chelyabinsk meteoroid tenuous
• 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 surface of (1) Ceres in visible light as seen by Dawn/VIR
• The Physical Characterization of the Potentially-Hazardous Asteroid 2004 BL86: A Fragment of a Differentiated Asteroid
• Phase Angle Effects on 3-micron Absorption Band on Ceres: Implications for Dawn Mission
• Three-dimensional spectral analysis of compositional heterogeneity at Arruntia crater on (4) Vesta using Dawn FC
• Variegation and space weathering on asteroid 21 Lutetia
• The surface of (4) Vesta in visible light as seen by Dawn/VIR