[meteorite-list] Vesta & HED's

From: MstrEman <mstreman_at_meteoritecentral.com>
Date: Sun, 13 May 2012 03:18:05 -0400
Message-ID: <CAPwdm9FvCAagwm7Gi92vfDbXP=zFPx4f_fQnzwsVC-gB8hHP6g_at_mail.gmail.com>

Keep in mind that there are now some non-Vesta originating eucrites
identified. So the pass state of knowledge holding that all HEDs were
from Vesta should be qualified with a caveat that "Most all eucrites
are from Vesta" or "with rare exception..." or "all most all..."

Elton

On 5/11/12, Benjamin P. Sun <bpsun2009 at gmail.com> wrote:
> This is not a surprise to me... or to most of us. But it may be "news"
> to some of you out there..
>
>
> http://www.jpl.nasa.gov/news/news.cfm?release=2012-132
>
> https://asunews.asu.edu/20120510_Vesta
>
> "Data also confirm a distinct group of meteorites found on Earth did,
> as theorized, originate from Vesta. The signatures of pyroxene, an
> iron- and magnesium-rich mineral, in those meteorites match those of
> rocks on Vesta's surface. These objects account for about 6 percent of
> all meteorites seen falling on Earth.
>
> This makes the asteroid one of the largest single sources for Earth's
> meteorites. The finding also marks the first time a spacecraft has
> been able to visit the source of samples after they were identified on
> Earth."
>
> ?Dawn observations enabled us to recognize that there are actually TWO
> large basins at the south pole, an older one named ?Veneneia? and a
> younger one named ?Rheasilvia?,? explains Williams.
>
> The Rheasilvia basin dominates the geology of Vesta, as the basin
> itself and its impact ejecta cover most of the southern hemisphere.
> The center of Rheasilvia has a central peak taller than Mt. Everest or
> Mauna Loa on Earth, similar in height to Olympus Mons on Mars. This
> basin appears to have excavated into the mantle of Vesta, exposing
> material spectrally similar to diogenite meteorites; Vesta?s crust is
> spectrally similar to eucrite and howardite meteorites, thus
> confirming that Vesta and its family of asteroids are the source of
> the howardite-eucrite-diogenite (HED) family of basaltic achondrite
> meteorites.
>
> ?For most planets and moons we see the pictures first, then have
> samples collected later to confirm our geologic interpretations. In
> the case of Vesta, thanks to the HED meteorites, we have the samples
> first, and must try to relate them to our emerging geologic picture of
> Vesta from the Dawn mission,?
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Received on Sun 13 May 2012 03:18:05 AM PDT