Vesta

A third type of commercial matches popular in South America is the wax vestas with a center of cotton threads or of a roUed and compressed thin and tough paper surrounded by and impregnated with wax each match is a miniature candle of long (ca 1 min) burning time. 

Fig. 3.3 Three oxygen isotope plot of lunar and Martian rocks and HED meteorites supposed to be fragnments of asteroid Vesta (after Wiechert et al. 2003)...

Poitrasson F, Freydier R (2005) Heavy iron isotope composition of granites determined by high resolution MC-ICP-MS. Chem Geol 222 132-147 Poitrasson F, Halhday AN, Lee DC, Levasseur S, Teutsch N (2004) Iron isotope differences between Earth, Moon, Mars and Vesta as possible records of contrasted accretion mechanisms. Earth Planet Sci Lett 223 253-266... 

Plots of uranium versus lanthanum (two refractory elements), and potassium versus lanthanum (a volatile element and a refractory element) for terrestrial and lunar basalts, HED achondrites (Vesta), and Martian meteorites. All three elements are incompatible elements and thus fractionate together, so their ratios remain constant. However, ratios of incompatible elements with different volatilities ( /La) reveal different degrees of volatile element depletion in differentiated bodies. After Wanke and Dreibus (1988). 

Nd system is used primarily to investigate the nature and timing of accretion of planetary bodies, such as the Earth, Moon, Mars, and Vesta. Current work is aimed at unraveling the roles of nebular and planetary processes in the isotopic systematics of these bodies. 

Myr after CAIs formed (Bizzarre et al., 2005). Taken together, these data imply that differentiation and crust formation began on the HED parent body 2.5-3 Myr after CAIs formed (Fig. 9.9). This, in turn, implies very rapid accretion, heating, and melting in Vesta, probably within 1 Myr of the origin of the solar system. 

Kleine, T., Mezger, K., Mtinker, C., Palme, H. andBischoff, A. (2004) Hf- W isotope systematics of chondrites, eucrites, and Martian meteorites chronology of core formation and early mantle differentiation in Vesta and Mars. Geochimica et Cosmochimica Acta, 68, 2935-2946. 

As already noted, spectral similarities between the various asteroid classes and specific types of meteorites provide a way to identify possible meteorite parent bodies. The Tholen and Barucci (1989) asteroid taxonomy has been interpreted as representing the types of meteorites shown in Table 11.1. Using the Bus et al. (2002) taxonomy, the C-complex asteroids are probably hydrated carbonaceous chondrites (e.g. Cl or CM). These carbonaceous chondrite asteroids probably accreted with ices and will be considered in Chapter 12. Some S-complex asteroids are ordinary chondrite parent bodies, but this superclass is very diverse and includes many other meteorite types as well. The X-complex includes objects with spectra that resemble enstatite chondrites and aubrites, and some irons and stony irons, although other X-complex asteroids are unlike known meteorite types. A few asteroid spectra are unique and provide more definitive connections, such as between 4 Vesta and... 

Comparison of the spectra of asteroid 4 Vesta and the eucrite Jonzac. The subdued and reddened spectra of Vesta suggest space weathering. Modified from Clark et al. (2002). 

Ghosh, A. and McSween, H. Y. (1998) A thermal model for the differentiation of asteroid 4 Vesta, based on radiogenic heating. Icarus, 134, 187-206. 

In most respects, asteroid 4 Vesta is geochemically similar to the Moon. As judged from howardite-eucrite-diogenite (HED) meteorites (see Chapter 6), Vesta is an ancient, basalt-covered world (Keil, 2002). Its rocks are highly reduced, and its depletions in volatile and siderophile element abundances resemble those of lunar basalts. And like the Moon, Vesta is hypothesized to have had an early magma ocean. The exploration of Vesta is now in progress, and within a few years we may have enough data to discuss it in a similar way that we have considered the Moon. 

Geologic data for asteroid 4 Vesta, (a) Spectral map of a part of the surface of Vesta as it rotates, showing the distribution of HED-like lithologies, modified from Binzel et at. (1997). (b) Interpretive geologic cross-section of Vesta, illustrating how HED meteorites might be distributed in the interior,... 

Binzel, R. P., Gaffey, M. J., Thomas, P. et al. (1997) Geologic mapping of Vesta from 1994 Hubble Space Telescope images. Icarus, 128, 95-103. 

Keil, K. (2002) Geological history of asteroid 4 Vesta The smallest terrestrial planet. In Asteroids III, eds. Bottke, W., Cellino, A., Paolicchi, P. and Binzel, R. P. Tucson University of Arizona Press, pp. 473-585. 

Righter, K. and Drake, M. J. (1996) Core formation in the Earth s Moon, Mars and Vesta. Icarus, 124, 513-529. 

Russell, C.T., plus 20 coauthors (2006) Dawn Discovery mission to Vesta and Ceres present status. Advanced Space Research, 38, 2043-2048. 

Usui, T. and McSween, H. Y. (2007) Geochemistry of 4 Vesta based on HED meteorites prospective study for interpretation of gamma-ray and neutron spectrometer for the Dawn mission. Meteoritics and Planetary Science, 42, 255-269. 

Mass fractions of cores (metallic iron) versus concentrations of FeO in mantles (oxidized iron) in the terrestrial planets and asteroid Vesta. After Righter et al. (2006). 

The origin of the components that were accreted to make up the planets is the subject of intense discussion. Chondrite-mixing models attempt to build the planets using known chondritic materials. These models are constrained by the mean densities, moments of inertia, and, to the extent that they are known, the bulk chemical and isotopic compositions of the planets. Mars and 4 Vesta can be modeled reasonably well by known types of chondritic material (Righter et al., 2006). However, the Earth seems to have formed, at least in part, from materials that are not represented in our collections of chondritic meteorites (see below). 

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