Color and Albedo Heterogeneity of Vesta from Dawn

Reddy, V.; Nathues, A.; Corre, Lucille Le; Sierks, H.; Li, Jian‐Yang; Gaskell, R. W.; McCoy, Timothy J.; Beck, A. W.; Schröder, Stefan; Pieters, C. M.; Becker, K. J.; Buratti, B. J.; Denevi, Brett W.; Blewett, D. T.; Christensen, Ulrich R.; Gaffey, M. J.; Gutiérrez-Marques, P.; Hicks, Michael; Keller, H. U.; Maue, T.; Mottola, S.; McFadden, L. A.; McSween, H. Y.; Mittlefehldt, David W.; O’Brien, D. P.; Raymond, C. A.; Russell, C. T.

doi:10.1126/science.1219088

Cited by 167 publications

(261 citation statements)

References 34 publications

(12 reference statements)

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“…Howardites and eucrites along with diogenites (HED meteorites) have been linked to asteroid (4) Vesta, on the basis of their spectral and mineralogical similarities derived from groundbased observations (e.g., McCord et al, 1970;Consolmagno and Drake, 1977;Gaffey, 1997;. This idea has been supported by recent spacecraft spectroscopic observations obtained by Dawn (e.g., Reddy et al, 2012b;De Sanctis et al, 2012), that shows Vesta as the most likely parent body of these meteorites. The Vesta asteroid family extends from the ν 6 secular resonance to the 3:1 mean motion resonance with Jupiter, providing a viable route for the delivery of these objects to the near-Earth space (Wisdom, 1985;Bottke et al, 2002).…”

Section: Discussionsupporting

confidence: 59%

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Sanchez

Michelsen

Reddy

et al. 2013

Icarus

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In the past, constraining the surface composition of near-Earth asteroids (NEAs) has been difficult due to the lack of high quality near-IR spectral data (0.7-2.5 µm) that contain mineralogically diagnostic absorption bands. Here we present visible (∼ 0.43-0.95 µm) and nearinfrared (∼ 0.7-2.5 µm) spectra of nine NEAs and five Mars-crossing asteroids (MCs). The YT1) as a V-type was made on the basis of its near-infrared spectrum since no visible spectrum is available for this asteroid. A mineralogical analysis was performed on six of the asteroids (those for which near-IR spectra were obtained or previously available). We found that three asteroids (241662 (2000 KO44), 19764 (2000 NF5), 138404 (2000) have mafic silicate compositions consistent with ordinary chondrites, while three others (4055 Magellan, 164121 (2003 YT1), 5407 (1992 AX)) are pyroxene-dominated basaltic achondrite assemblages. In the case of 5407 (1992 AX) we found that its basaltic surface composition contrasts its taxonomic classification as a S-type.

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Section: Discussionsupporting

confidence: 59%

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Sanchez

Michelsen

Reddy

et al. 2013

Icarus

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“…In the Clementine color ratio map the lobe shows comparable colors to the Rheasilvia ejecta (ranging from cyan via green to yellowish colors) within and around Vesta's south pole. The bright green/yellow indicates a deeper 1-lm absorption band and is consistent with terrains interpreted to be diogenite-rich howardite, such as in the Rheasilvia basin (Reddy et al, 2012a). This compositionally different material is also evident in the Dawn GRaND data which shows an eastern low-iron lobe extending northward from the Rheasilvia basin .…”

Section: Rheasilvia Ejectasupporting

confidence: 55%

“…This striking spectral feature appears as a swath of bright material in the FC clear filter images. Reddy et al (2012a) suggested it to be a thin mantle of material probably ejected during the Rheasilvia impact event. Using the spatially higher resolved LAMO data, the lobe region appears to have a smoother texture than typical vestan terrains outside the Rheasilvia basin, and is crosscut in some parts by numerous small grooves oriented approximately in the north-south direction.…”

Section: Rheasilvia Ejectamentioning

confidence: 99%

“…The diffuse ejecta mantle shows up as dark orange to red colored material in Clementine color ratio maps (see right side of Fig. 2C), due to a steeper spectral slope in the visual wavelength range (Reddy et al, 2012a;Le Corre et al, 2013). Due to the localized occurrence of the increased spectral slope, we interpret it to be a mixture of impactor material and a lithology excavated by the Octavia impactor.…”

Section: Rheasilvia Ejectamentioning

confidence: 99%

“…We primarily used a combination of color ratios introduced for the Clementine mission (Pieters et al, 1994), which has been applied on FC data (Reddy et al, 2012a). In the following, this color composite is called 'Clementine color ratios' (see Fig.…”

Section: Framing Camera Image Productsmentioning

confidence: 99%

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Imprint of the Rheasilvia impact on Vesta – Geologic mapping of quadrangles Gegania and Lucaria

Schäfer¹,

Nathues²,

Williams³

et al. 2014

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a b s t r a c tWe produced two 1:250,000 scale geologic maps of the adjacent quadrangles Av-6 Gegania and Av-7 Lucaria, located in the equatorial region of (4) Vesta (0-144°E, 22°S to 22°N). The mapping is based on clear and color filter images of the Framing Camera (FC) onboard the Dawn spacecraft, which has captured the entire illuminated surface of Vesta with high spatial resolution (up to $20 m/pixel), and on a digital terrain model derived from FC imagery. Besides the geologic mapping itself, a secondary purpose of this work is to investigate one of the most prominent morphological features on Vesta, namely the aggregation of several giant equatorial troughs termed the Divalia Fossae, most probably formed during the Rheasilvia impact near Vesta's south pole. The up to 465 km long and 22 km wide troughs show height differences of up to 5 km between adjacent troughs and ridges. Another imprint of the Rheasilvia impact is the >350 km long and $250 km wide swath of ejecta crossing quadrangle Av-6 Gegania. This lobe shows a distinct appearance in FC color ratios and a high albedo in FC images, indicating a mineralogical similarity to material typically found within the Rheasilvia basin, in particular composed of diogenite-rich howardites. Almost the entire northern half of the mapping area shows the oldest surface, being dominated by upper crustal basaltic material. To the south, increasingly younger formations related to the Rheasilvia impact occur, either indicated by the troughs formed by Rheasilvia or by the Rheasilvia ejecta itself. Only medium sized impact craters with diameters less than 22 km occur within the two mapped quadrangles. Some of the craters exhibit ejecta blankets and/or distinctly dark or bright ejecta material in ejecta rays outside and exposures within the crater, and mass-wasting deposits down crater slopes, forming the youngest surfaces.

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Mass‐wasting features and processes in Vesta's south polar basin Rheasilvia

et al. 2013

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[1] The Rheasilvia crater is Vesta's largest impact basin. It is a 500 km diameter complex crater centered near the south pole and overlying the 400 km diameter impact basin Veneneia. Using Framing Camera (FC) data from the Dawn spacecraft's Low Altitude Mapping Orbit (20 m/pixel) and a digital terrain model derived from High Altitude Mapping Orbit stereo data, we identified various mass-wasting features within the south polar region. These features include intra-crater mass movements, flow-like and creep-like structures, slumping areas, landslides, and curved radial and concentric ridges. Intra-crater mass-wasting features are represented by lobate slides, talus material, dark patches on the crater wall, spurs along the crater rim and boulders. Slumping areas develop in compact material, whereas landslides form in relatively loose material. Both may be triggered by seismic shaking induced by impacts. Intra-crater mass wasting and slid and slumped materials are homogeneously distributed throughout the basin. Slumping and sliding processes have contributed most efficiently to basin degradation. Flow-like and creep-like features originate from granular material and cluster between 0 ı E and 90 ı E, an area exposing shocked and fractured material from the Rheasilvia impact event. The radial curved ridges are likely to be remnants of the early Rheasilvia collapse process, when radially moving masses were deflected by the Coriolis Effect. The concentric ridges are artifacts from the crater rim collapse. Curved ridges at the intersection of Rheasilvia and Veneneia, and on Rheasilvia's central peak, may also have been influenced by the Rheasilvia basin relaxation process, and an oblique impact, respectively.

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Color and Albedo Heterogeneity of Vesta from Dawn

Cited by 167 publications

References 34 publications

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Imprint of the Rheasilvia impact on Vesta – Geologic mapping of quadrangles Gegania and Lucaria

Mass‐wasting features and processes in Vesta's south polar basin Rheasilvia

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