[meteorite-list] Meteoroids Before Meteorites

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Fri, 13 Mar 2009 05:41:57 -0700 (MST)
Message-ID: <57106.71.226.60.25.1236948117.squirrel_at_timber.lpl.arizona.edu>

Hi Eric, Graham, etc:

How many hours do you have? I do whole lectures on this subject.

There are probably several experts out there listening to this whole
conversation. My experience is probably several years out of date, but
there have been a number of on-going "discussions" of what is space
weathering and why do the meteorites we see not look quite like what we
have seen in space (even when we get close up).

There is rumor that there will be results published in Nature on the
composition of the TC3 meteorite. I am sure it will hit the list soon
thereafter.

I have heard that the spectrum of TC3 is similar to an F asteroid. That
means that its spectrum is flat. However, I do not know what the spectral
range of the observations was. It is likely not to be over a very large
spectral range, so may have "missed" diagnostic features at the red and
blue ends of the visible spectrum (those things that identify minerals).

However, I do know that TC3 was a solid rock. It was tumbling, but
spinning one in less than 2 minutes. As such, no dust could stay on its
surface, not enough gravity.

M-class asteroids have flat to slightly reddish visible and near-infrared
spectra and have albedos in the 10% to 20% range. It is thought that
M-class asteroids are related to iron meteorites, but there may be some
exceptions.

Maybe it is time for an article in Meteorite magazine on this. Any
volunteers? Might be a nice summary paper for a grad student!

Larry

On Fri, March 13, 2009 2:57 am, ensoramanda at ntlworld.com wrote:
>

>
> and following on from that...what would an iron meteroid/aseroid look
> like in space....would there be any sign of metallic lustre or would
> space weathering have darkened the surface?
>
> Graham Ensor
>
>
> ---- Eric Wichman <eric at meteoritewatch.com> wrote:
>
>> Hi all,
>>
>>
>> While looking at photos of our most recent extraterrestrial visitor,
>> the West meteorite, I was wondering what the "meteoroid" looked like
>> while floating around in space... Look how nice and white this piece is
>> on the "inside". http://www.rocksfromspace.org/133g_Interior.JPG Fusion
>> crust is only formed while entering our planets atmosphere. Meaning that
>> this meteorite was obviously whitish in color while still a meteoroid.
>> Right?
>>
>>
>> Space is a vacuum, and a vacuum preserves things right? Look at the
>> moon and all the wonderful craters and how wonderfully preserved they
>> are. The moon never changes color except when viewed through our
>> atmosphere. From space it looks the same as it did millions of years
>> ago.
>>
>> Does this mean that the West meteoroid, while in space and "before" it
>> hit our planet, was white? I mean, it's not like the minerals that make
>> up the meteoroid change colors before hitting our planet. Right?
>>
>> I guess the reason I ask this is that we all see photos of asteroids
>> that are dark gray, gray-black or brown blobs of space rock floating
>> around the solar system. I think our perception of meteorites are quite
>> different. We tend to think of rocks from space as dark rocks floating
>> around aimlessly and randomly bumping into one another occasionally
>> sending pieces our way to be pulled in by our planets gravity.
>>
>> Are there huge white rocks floating around out there? And if so,
>> wouldn't they be slightly easier to spot than a dark blob of an
>> asteroid?
>>
>> I hope these aren't dumb questions.
>>
>>
>> Eric
>> ______________________________________________
>> http://www.meteoritecentral.com
>> Meteorite-list mailing list
>> Meteorite-list at meteoritecentral.com
>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>>
>
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
Received on Fri 13 Mar 2009 08:41:57 AM PDT