[meteorite-list] Lutetia

[MexicoDoug]

Hey Benjamin

Spectroscopy is one of many tools in the toolbox which unfortunately is 
not a good toolbox until you can scoop up a sample and look at it.

This looks like you are responding to me since I mentioned paint in my 
reply of the difficulty of interpreting convoulted spectra made of 
billions of years of dust and collisions.

But I'm not really sure because I called it speculation; so whoever you 
are talking about dismissing it, maybe they can speak up.  An 
astronomer doing chemical spectras has a light path through earth's 
atmosphere, across space beyond Timbuctu to arrive at a sample that 
hasn't been cleaned for a few billion years and has been subjected to 
all varieties of meteoritical, asteroidal, cosmic particle, as well as 
the normal alteration processes.

Then he has a collection of meteorites which is probably far from 
complete, but he is lucky if by chance one of them fairly matches after 
he does his best to cheat by starting with the meteorite fresh cut 
spectrum assuming it is his best match and working his way backwards 
doing what he can along the way to lower this peak or raise that one 
and then when all the dust is cleared :-), he just shows his spectrum 
of the asteroid and his spectrum of the meteorite after his series of 
manipulations and says Eureka, I've found it!

The down side is minimal, the astronomer doesn't even get much of an 
academic spanking and speculation is healthy and fun.  If he happens to 
be clever and lucky though, the upside is it really is a match and he 
goes down as the guy who discovered the composition of an asteroid or 
asteroid class.

In the case of Lutetia, a closer view from Rosetta was significant 
becuase it eliminated many erroneous conclusions from other spectra of 
it that had been taken from Earth distance and it confirmed there are 
no organic materials, and water is scarce.

Basically, after gravitational measurements, a different tool than 
spectroscopic ones is added, and it shows Lutetia is heave for its size 
does the idea it has a lot of metal start sounding good.  But to say it 
is an E-meteorite class instead, for example of a Bencubbinite or 
perhaps one of the many types of millions of asteroids that we have not 
seen specimens from ... it's a real concrete jungle out there ...

So, speculative is the correct word to use.  And after reviewing the 
limitations of the spectroscopy, let's paint the town with it.

Most interesting to me was the very large crater found.  Now, luckily 
the Spectrum of Lutetia is rather unique.  I the case of Vesta, the 
scale fell in favore of it being understood as the HED source after a 
chain of Vestoids was found spanning Vesta's orbit to a Kirkwood gap.  
In the case of Lutetia, let's see if the 10 million kilometers it needs 
to span have any baby Parisians along a path in an analolgous 
manner...Verrrrrrrrry interrrresting, but ... not stupid!

Kindest wishes
Doug


-----Original Message-----
From: Benjamin P. Sun <bpsun2009 at gmail.com>
To: meteorite-list <meteorite-list at meteoritecentral.com>
Sent: Sat, Nov 12, 2011 3:32 pm
Subject: Re: [meteorite-list] Lutetia


Regolith is mostly powdered rock and pebbles from the parent body that
may or may not be compacted at the surface.
So why should the reflectance spectra from Lutetia's regolith be
totally dismissed? Are you dismissing Spectroscopy of asteroids
altogether?
If the "paint" derived from the parent body, then analysis of the
"paint" could possibly tell us something about the parent body itself.
Yes?
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