Vesta system

At the time of writing there is only one manufacturer of micro/nano-TA equipment Anasys Instruments, (www.anasysinstruments.com). They supply the hardware and software for local thermal analysis and thermal imaging that can be interfaced with the most popular types of atomic force microscope. More recently they have launched an instrument based on an optical microscope, the Vesta system, which is simpler to use than an atomic force microscope but the spatial resolution is limited to approximately 1.5 micrometers, see Fig. 7.22. The Wollaston probes are supplied by Veeco (www.veeco.com) and are, therefore, compatible only with Veeco AFMs. The nanoprobes are supplied by Anasys Instruments and can be used with most popular makes of AFM. In addition, Anasys Instruments supply calibration kits containing temperature standards. More recently they have launched an instrument based on an optical microscope, the Vesta system, which is simpler to use than an atomic force microscope, but the spatial resolution is limited to approximately 1.5 pm. 

Figure 7.22. Vesta system for micro-thermal analysis. Courtesy of Anasys Instruments.

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. 

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Figure 9.2 Fraction of stars with excess emission at IRAC wavelengths (between 3.6 and 8 um) as a function of the age of the stellar group. In addition to the data presented in Hernandez et al. (2008) and references therein, we have included the disk frequencies in the TW Hya association (Weinberger et al. 2004), and from the FEPS sample of Sun-like stars (Silverstone et al. 2006). The dot-dashed line is the least-squares fit to the L-band data from Haisch et al. (2001b). Above the plot we show a comparison to the formation timescale of CAIs, chondrules, and the asteroid Vesta in the Solar System. As we discuss in Section 9.4 there is evidence that CAIs formed early, in the first Myr of disk evolution.

Cosmochemical analysis of meteorites provides important constraints on the timing of planet formation. The first differentiated bodies formed <1.5 Myr after the start of the Solar System. However, processing of dust grains in the nebula and the formation of planetesimals continued for at least the first 2-3 Myr. Vesta formed within 5 Myr, while Mars was fully grown and differentiated by 10-20 Myr. Earth took longer to grow, and it was not until 50-150 Myr that the planet was fully formed and the Moon was present. 

Most meteorites are depleted in moderately volatile and highly volatile elements (see Figures 2-4). The terrestrial planets Earth, Moon, Mars, and the asteroid Vesta show similar or even stronger depletions (e.g., Palme et aL, 1988 Palme, 2001). The depletion patterns in meteorites and in the inner planets are qualitatively similar to those in the ISM. It is thus possible that the material in the inner solar system inherited the depletions from the ISM by the preferential accretion of dust grains and the loss of gas during the collapse of the molecular cloud that led to the formation of the solar system. There is, however, little support for this hypothesis ... 

The primary feature of the main asteroid belt is its great depletion in mass relative to other regions of the planetary system. The present mass of the main belt is 5 X 10 m , which represents 0.1 -0.01 % of the solid mass that existed at the time planetesimals were forming. There are several ways the main asteroid belt could have lost most of its primordial mass. Substantial loss by collisional erosion appears to be mled out by the preservation of asteroid Vesta s basaltic cmst, which formed in the first few million years of the solar system (Davis et al., 1994). More plausible models are based on the existence of orbital resonances associated with the giant planets. 

Figure 17 Cr excess in bulk meteorites and bulk planets versus Mn/Cr ratios. The line through Orgueil, Allende, and Earth and the CH meteorite HH237 defines a Mn/ Mn ratio of (8.40 2.2) X 10. This is three million years earlier than the time of differentiation of Vesta (Lugmair and Shukolyukov, 1998). The Mn/ Mn ratio of carbonaceous chondrites and the Earth could be interpreted as the time of Mn/Cr fractionation in the solar system. The fractionation of other moderately volatile elements may have occurred at the same time and by the...

The formation of planetesimals may have been very rapid after the initial formation of the solar nebula. Objects as large as Mars would have grown within 10 yr (Weatherill, 1990). The core of the asteroid Vesta may have formed within only 3-4 Myr, and lavas flows on its surface may have occurred at this time also (Yin et al, 2002). Bodies like Vesta would have collided rapidly, aggregating their cores to form larger planetoids and then planets. The date of core formation in the Earth remains controversial but may have been as little as 30 Myr or less after the birth of the solar system (Kleine et al, 2002). Yin et al (2002) suggest that the aggregation of the Earth s core took place within 29 Myr. The core of Mars may have formed as early as within 13 Myr. 

The first asteroid was discovered serendipitously by the Italian astronomer Giuseppe Piazzi (1746-1826) on the night of January 1,1801. This asteroid, subsequently called Ceres after the Roman goddess of com and harvests, has a diameter of 584 mi (940 km) and is the largest asteroid in our solar system. The next three largest asteroids, Pallas, Juno, and Vesta, were discovered in 1802,1804, and 1807. 

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