[meteorite-list] Vesta

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Fri, 16 Jan 2015 14:11:05 -0700
Message-ID: <4b49a95da0d1f983e25619757d95009b.squirrel_at_webmail.lpl.arizona.edu>

Here is the abstract to the original paper published in Science in 1970.

Asteroid vesta: spectral reflectivity and compositional implications.

McCord TB, Adams JB, Johnson TV.

Abstract

The spectral reflectivity (0.30 to 1.10 microns) of several asteroids has
been measured for the first time. The reflection spectrum for Vesta
contains a strong absorption band centered near 0.9 micron and a weaker
absorption feature between 0.5 and 0.6 micron. The reflectivity decreases
strongly in the ultraviolet. The reflection spectrum for the asteroid
Pallas and probably for Ceres does not contain the 0.9-micron band. Vesta
shows the strongest and best-defined absorption bands yet seen in the
reflection spectrum for the solid surface of an object in the solar
system. The strong 0.9-micron band arises from electronic absorptions in
ferrous iron on the M2 site of a magnesian pyroxene. Comparison with
laboratory measurements on meteorites and Apollo 11 samples indicates that
the surface of Vesta has a composition very similar to that of certain
basaltic achondrites.

Larry

> Hi Andre,
>
> Even before the NASA Dawn program, scientists had made a strong
> connection between the HED meteorites and Vesta. The brief paper at
> the link below gives a general explanation of the connection. In the
> years since, Dawn has solidified that connection.
>
>>From the text :
>
> Many lines of evidence indicate that
> meteorites are derived from the asteroid belt but, in
> general, identifying any meteorite class with a particular
> asteroid has not been possible. One exception
> is asteroid 4 Vesta, where a strong case can be made
> that it is the ultimate source of the howardite-eucritediogenite
> (HED) family of basaltic achondrites. Visible
> and near infrared reflectance spectra (Fig. 2) first
> pointed to a connection between Vesta and the basaltic
> achondrites [4]. Experimental petrology demonstrated
> that the eucrites (the relatively unaltered and unmixed
> basaltic achondrites) were the product of approximately
> a 10% melts [5]. Studies of siderophile element
> partitioning suggested that this melt was the residue
> of an asteroidal-scale magma ocean [6]. Mass
> balance considerations point to a parent body that had
> its surface excavated, but remains intact [7]. Modern
> telescopic spectroscopy has identified kilometer-scale
> "Vestoids" between Vesta and the 3:1 orbit-orbit resonance
> with Jupiter [8]. Dynamical simulations of impact
> into Vesta demonstrate the plausibility of ejecting
> relatively unshocked material at velocities consistent
> with these astronomical observations [9]. Hubble
> Space Telescope images (Fig. 3) show a 460 km diameter
> impact basin at the south pole of Vesta [10].
> Spectroscopic studies of near-Earth asteroids revealed
> three small objects with basaltic composition which are
> arguably the proximal source of the HED meteorites,
> having reached one of Jupiter's resonances faster than
> the objects observed by [10] after which they quickly
> evolved into Mars crossing objects and then near-Earth
> objects. [11].
>
> Hope this helps.
>
> Best regards,
>
> MikeG
>
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>
>
> On 1/16/15, Deborah Anne K. Martin via Meteorite-list
> <meteorite-list at meteoritecentral.com> wrote:
>> Hello all,
>>
>> Could someone explain to me exactly how it was determined that certain
>> meteorites, like Tatahouine, originally came from Vesta ?
>>
>> I appreciate the help.
>>
>> Andre
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Received on Fri 16 Jan 2015 04:11:05 PM PST