[meteorite-list] Question about NWA 869

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Fri, 4 Nov 2011 14:49:40 -0400 (EDT)
Message-ID: <8CE6939A4B408F6-D64-100ACD_at_webmail-d084.sysops.aol.com>

Just saw Zelimir's informative post from yesterday, if that is what he
does for 869, he must have the world's best megadocumebnted collection
;-), like we all aspire.

I need a correction to what I just posted a few minutes ago:

I gave the amount lost to ablation in the prior post, the correct
numbers for the amount dropped as meteorites are as follws and Dean
Bessey's estimate for NWA 869 of 7 tons of rocks in the strewn field
and fits just right for the diameters/radii given in the paper and by
John,

diameter (meters) max recoverable mass
0.1 0.14 kg
0.3 3.8
0.5 18
1.0 141
1.5 477
2.0 1.1 ton
2.5 2.2
3.0 3.8
3.5 6.1
4.0 9.0
4.5 13
5.0 18

Nice to keep these numbers in mind when we think about our well cared
for boxes of space chocolates! If NWA 869 were a limited fall the
prices would have sent it right back to the cosmos ... something to
think about. Nice to think about next time you see your
wife/husband/boy/girlfriend!

Best
Doug



-----Original Message-----
From: MexicoDoug <mexicodoug at aim.com>
To: meteorite-list <meteorite-list at meteoritecentral.com>
Sent: Fri, Nov 4, 2011 1:58 pm
Subject: Re: [meteorite-list] Question about NWA 869


Yes Mel, John's 4-5 meters in diameter statement corresponds to the
average 2 meter radius in the reference. FYI, a typical entering
meteoroid that experiences a loss of 92.5% (the factor of its material
ton ablation as concluded by the authors) would drop this much material
for our collections:

diameter (meters) max recoverable mass
0.1 2 kg
0.3 50
0.5 200
1.0 1.7 ton
1.5 5.9
2.0 14
2.5 27
3.0 47
3.5 75
4.0 112
4.5 159
5.0 218

Of course the factor of 92.5% loss will vary depending on the angle it
enters, speed, composition and integrity, as well as the initial size
and shape, so they are all gross estimates.

Kindest wishes
Doufg



-----Original Message-----
From: Melanie Matthews <miss_meteorite at yahoo.ca>
To: MexicoDoug <mexicodoug at aim.com>; meteorite-list
<meteorite-list at meteoritecentral.com>
Sent: Fri, Nov 4, 2011 12:42 pm
Subject: Re: [meteorite-list] Question about NWA 869


Found this:


"Scientists figure the meteoroid that was blasted off the parent body
was maybe
4 to 5 meters in diameter before atmospheric entry. Even with ablation
loss of
90 to 95% about 7 tons dropped on the Sahara Desert."

http://www.meteorite-times.com/micro-visions/nwa-869-inclusions/


?
-----------
-Melanie "MetMel" - avid meteorite collector/enthusiast from Canada!
IMCA#: 2975
eBay: metmel2775


I eat, sleep and breath meteorites 24/7.


----- Original Message -----
From: MexicoDoug <mexicodoug at aim.com>
To: miss_meteorite at yahoo.ca; meteorite-list at meteoritecentral.com
Cc:
Sent: Friday, November 4, 2011 1:03:47 AM
Subject: Re: [meteorite-list] Question about NWA 869

PS

Referencing the same article that considered the free floating for 4-5
million
year 869-parent meteoroid, also commented that the age of some of the
regolith
soil/glue that formed the fantastically brecciated meteoroid of our
envy had
itself exposure time of as long as 16 million years:

"Assuming that 4 Ma is the time of transit irradiation, several
lithologies have
been preirradiated up to 16 Ma in the parent body regolith."


-----Original Message-----
From: MexicoDoug <mexicodoug at aim.com>
To: miss_meteorite <miss_meteorite at yahoo.ca>; meteorite-list
<meteorite-list at meteoritecentral.com>
Sent: Fri, Nov 4, 2011 3:49 am
Subject: Re: [meteorite-list] Question about NWA 869


NWA 869 represents an L chondritic regolith breccia containing
preirradiated components.? The meteoroid had an initial radius of about
2 m with a mass of about 110 metric tons. The transit time to Earth was
about 4-5 Ma. Large variations of shielding depths between samples
indicate that break-up of the meteoroid must have occured high in
atmosphere. This would also explain the large inferred ablation loss,
which is typical for large chondrite showers.

Ref:

"The L3-6 Regolith Breccia Northwest Africa 869: Petrology, Noble
Gases, and Cosmogenic Radionuclides"
Metzler, K.; Ott, U.; Welten, K. C.; Caffee, M. W.; Franke, L.
39th Lunar and Planetary Science Conference, (Lunar and Planetary
Science XXXIX), held March 10-14, 2008 in League City, Texas.
LPI Contribution No. 1391., p.1120
Publication Date: 03/2008

http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1120.pdf



-----Original Message-----
From: Melanie Matthews <miss_meteorite at yahoo.ca>
To: MeteoriteList <meteorite-list at meteoritecentral.com>
Sent: Fri, Nov 4, 2011 2:10 am
Subject: [meteorite-list] Question about NWA 869


Hi list,

Are there any estimates in how long ago this wonderful meteorite fell
to Earth,
and how large it might have been before it entered the atmosphere? It
must have
been a massive meteoroid, much larger than the one that produced the
Buzzard
Coulees.

?
-----------
-Melanie "MetMel" - avid meteorite collector/enthusiast from Canada!
IMCA#: 2975
eBay: metmel2775


I eat, sleep and breath meteorites 24/7.
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Received on Fri 04 Nov 2011 02:49:40 PM PDT