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Vesta is the asteroid with the largest albedo variation among the known rocky Solar System objects and shows a widespread occurrence of dark material (DM) and bright material (BM) units. In the first observation phases by the Dawn spacecraft, two main extensions of low albedo areas were identified on Vesta and found to be closely correlated with carbonaceous, OH-rich, material. In this work we use...
The Vesta gravity field and related physical parameters have been precisely measured using 10-months of radiometric Doppler and range data and optical landmark tracking from the Dawn spacecraft. The gravity field, orientation parameters, landmark locations, and Vesta’s orbit are jointly estimated. The resulting spherical harmonic gravity field has a half-wavelength resolution of 42km (degree 20)....
NASA’s Dawn spacecraft orbited Vesta for approximately one year, collecting thousands of hyperspectral images of its surface. The mission revealed that Vesta’s surface shows the largest variations in surface albedo on asteroids visited thus far, due to the presence of dark and bright materials at the local scale (i.e. 0.1–10km).The aim of this work is to characterize the photometric properties of...
We use the shape and gravity field of Vesta determined from observations of the Dawn spacecraft to place constraints on the asteroid’s interior structure. We compute a three-layer interior structure model by minimizing the power of the residual gravity anomaly. The densities of the mantle and crust are based on constraints derived from the Howardite–Eucrite–Diogenite (HED) meteorites.Vesta’s present-day...
Deposits of dark material appear on Vesta’s surface as features of relatively low-albedo in the visible wavelength range of Dawn’s camera and spectrometer. Mixed with the regolith and partially excavated by younger impacts, the material is exposed as individual layered outcrops in crater walls or ejecta patches, having been uncovered and broken up by the impact. Dark fans on crater walls and dark...
Vesta spectra have prominent near-infrared absorption bands characteristic of pyroxenes, indicating a direct link to the howardite, eucrite and diogenite meteorites. Many localized dark and bright materials are present on Vesta’s surface. Here we focus on the bright material (BM) units to determine their spectral properties, their origin, the presence of mineralogical phases different from pyroxenes,...
We examine the gravity and topography of the asteroid 4 Vesta, as recently revealed by the Dawn mission. The observed gravity is highly correlated with the observed topography, and suggests little lateral variation in density. The variance spectra of both gravity and topography follow power laws which are very similar to those seen for the Moon, Mars, Venus, and Earth. A significant way in which Vesta...
A 20th degree ellipsoidal harmonic gravity field of Vesta is determined by processing radiometric Doppler and range data from the Dawn mission. The gravity field shows sensitivity up to degree 18 and the coefficients are globally determined on average to degree 15. Gravity anomalies are mapped to the Brillouin ellipsoid (304×289×247-km), which is a substantially closer fit to the surface than the...
Remote sensing data acquired during Dawn’s orbital mission at Vesta showed several local concentrations of high-albedo (bright) and low-albedo (dark) material units, in addition to spectrally distinct meteorite impact ejecta. The thermal behavior of such areas seen at local scale (1–10km) is related to physical properties that can provide information about the origin of those materials. We use Dawn’s...
The Dawn spacecraft recently observed the presence of dark material, which in turn proved to be associated with the presence of OH and H-rich material, on the surface of Vesta. The source of this dark material has been almost unanimously identified with the low albedo asteroids, likely analogous to the carbonaceous chondrites found on Earth, that impacted on Vesta over its lifetime. However, it is...
The asteroid Vesta is a differentiated planetesimal from the accretion phase of Solar System formation. Although its present-day shape is dominated by a non-hydrostatic fossil equatorial bulge and two large, mostly unrelaxed impact basins, Vesta may have been able to approach hydrostatic equilibrium during a brief early period of intense interior heating. We use a finite element viscoplastic flow...
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