[meteorite-list] Never underestimate or dismiss Spectroscopy

From: MstrEman <mstreman_at_meteoritecentral.com>
Date: Tue, 15 May 2012 10:10:20 -0400
Message-ID: <CAPwdm9Gk76-tRNUvSzEm2yS-JNX22Ra+Q2H_sLXFZFr_YaDyrw_at_mail.gmail.com>

The DAWN mission Public Affairs Office(?) wrote, "Recent results of
the Dawn mission show that the asteroid Vesta is the only known
remnant from a big early phase of planet formation."

In Clintonesque fashion: the truth of this assertion rest on what the
definition of "known" is. Vesta is NOT the only "known remnant" in
the minds of those that have looked into the early solar system
composition. It may, for the present, be the only "known --up close"
example that mankind has visited.

It would be bad science reporting if it were the intention in the
first paragraph of this article to casually dismiss Ceres, Pallas
and, a host of other smaller remnant, irregular chunks of planetary fragments
whose spectrography has been studied and whose size indicates they
would be well differentiated, else have been derived from a disrupted
first or second generation planetesimal.

With access to super computers, we've come a long way in the past
decade to working backwards in time to identify past orbital
distances, conflicts/collisions and the origins of asteroid families.
Analysis of orbits, resonances, voids and etc., suggest that there
were over 50 minor planets/secondary planetesimals present in the
early solar system which are no longer in solar orbit as whole
bodies.( i.e disrupted, ejected or absorbed).

 Earth has only sampled 5?% of the "known" disrupted bodies that we
have spectra from and it remains frankly naive to couch the Dawn
"preliminary" data as the Rosetta Stone for the early solar system.
The admonition to "never dismiss nor underestimate spectrography"has
been violated by this very article. The headline comes across as
oblivious to the existing body of research.

Generally speaking, stating to the HED clan of meteorites are mainly
derived from "Vesta" is acceptable so long as we understand ( Caveat
#1) that they could also be from any of the Vesta family: any of
those 6000+ bodies populating the Vesta orbital region. Many of
those are over 1 km size and most but not all have Vesta matching
spectra/albedos.

In light of a constant "sound-bite-mentality" in the media, it is easy
to forget that Vesta is the largest remnant of a family of asteroids
and no one can say with scientific certainty that a given meteorite
came from Vesta-proper vs being from one of the Vesta clan. Without
this knowledge, a new comer to the meteorite collecting "hobby" might
naively believe that we know for absolute certainty that a particular
HED is only from 4 Vesta-proper to the exclusion of all other existing
bodies.

The second caveat is covered elsewhere in recent list commentary: the
fact that we do have some non-Vestian eucrites was panned as
"insignificant". Well, Au contraire-- the existence of a but a
solitary example is proof that the "basaltic, sub/minor-planetary
differentiation process" happened on more than a single body. Adding
credibility to the planetary-science model. Naively stating over
and over that "all eucrites " come from Vesta" won't make it true.
Doing so retards the advancement meteorite science.

While I think the results from Dawn are significant. It is hard to
compete with manned space flight and asteroid landings for due
attention. Scientist tend to be giddy over their mission success but
fail to fully convey the real picture to the journalist-- whose first
obligatory action is to strip the interview of caveats and transpose
as least two values.(sarcasm) This press piece isn't the big picture
by any means but an important part of laying out the jigsaw pieces in
more orderly fashion. I do trust the scientist a lot more than I do
the press so I look forward to what is really said by them.

Elton
Received on Tue 15 May 2012 10:10:20 AM PDT