Meteor mit Fragmentation und Detonation, 17.10.12, 19'42 PDT, California

[karmaka]

Und hier ist ein Fernsehbericht von KOVR Sacramento zu Bobs Fund:

http://sports.yahoo.com/video/yahoonewsvideo-15749570/meteorite-hunter-finds-gem-in-novato-31003613.html

[herbraab]

Abschnitt mit sichtbarer Kruste und Schnittfläche währe perfekt, aber nur Kruste währe auch schon toll.

Sorry, ein besseres Bild von der Kuste des großeren Stücks (oder ein Bild, auf dem Kruste und Anschnitt gleichermaßen zu sehen sind) habe ich leider nicht...


Herbert

[karmaka]

Hier nun die offizielle Fundseite des 'Novato meteorite consortium', allerdings noch ohne Bobs Fund:

http://asima.seti.org/n/

Jason Utas Novato N3 (79g):

http://cams.seti.org/Utas-N03.jpg

Und noch Bilder von Brien Cooks Novato N2

https://www.facebook.com/media/set/?set=a.4829050482734.195683.1190747054&type=1&l=286c2eb13f&_fb_noscript=1

[karmaka]

Ein weiterer Fernsehbericht über Brien Cooks Fund:

http://www.news10.net/news/article/215400/2/Sacramento-meteor-hunter-gets-second-find-in-6-months

[karmaka]

Jason Utas N3 (79g) kann seit gestern auf diesem Foto mit hoher Auflösung sehr schön betrachtet werden:

http://upload.wikimedia.org/wikipedia/en/9/90/Novato_Meteorite_Number_3.jpg

[karmaka]

Hier ist noch der Fundreport mit Bildern von Bob Verish zu seinem N04 Fund und der Einschlagdelle im Asphalt.

http://meteorite-recovery.tripod.com/2012/novato/novato.htm

und sein Artikel in Meteorite-Times:

http://www.meteorite-times.com/bobs-findings/the-recovery-of-the-novato-meteorite-that-fell-on-2012-october-18-0244-ut-oct-17-1944-pdt/

Wie man sieht, wurden die meisten Novato-Exemplare auf asphaltierten Straßen gefunden.

Interessant ist auch der Fundort von Utas' N03, der unbeschadet auf einer Spur für Linksabbieger 'überlebt' hat, bevor er gefunden wurde.

[karmaka]

Hier noch ein kurzes Foto-Update der letzten Funde:

N04 von Bob Verish:

http://www.galacticanalytics.com/wp-content/uploads/wppa/7.jpg
http://www.galacticanalytics.com/wp-content/uploads/wppa/8.jpg

N05 24,264 g , gefunden von Jason Utas am 2.11.

http://www.galacticanalytics.com/wp-content/uploads/wppa/9.jpg
http://www.galacticanalytics.com/wp-content/uploads/wppa/10.jpg

Quelle: http://www.galacticanalytics.com

[karmaka]

Novato N06

23g, gefunden am 11.11.12

http://cams.seti.org/Novato06-thumb.jpg

Ein 'Gruppenbild' der Funde:

http://cams.seti.org/MeteoritesFoundSoFar-thumb.jpg

[karmaka]

Durch eine neue SkyCam-Aufnahme des Lick Observatory wurde nun die Flugbahn noch einmal korrigiert und ergibt folgende Grafik:

http://cams.seti.org/Novatomap1.jpg

[karmaka]

Novato N01 wird nun auch genauer analysiert

Samples of N01 : http://cams.seti.org/N01sampling-thumb.jpg

Samples of N01 were distributed to Novato meteorite consortium members today, following a controlled break at NASA Ames Research Center. The breaking permitted the measurement of the tensile strength. When the inside of the meteorite was revealed, it turned out to be mostly of the dark lithology variety. Only small outside parts of Novato N01 were light colored. Fragment N01-1d was returned to the Rivera family.

Quelle: http://cams.seti.org/

[karmaka]

Nach Rubins Bekanntmachung auf der list auch hier noch schnell der Link, der Vollständigkeit wegen.

LINK

Novato        38.10900°N, 122.61053°W

Marin County, California, United States

Fell: 17 Oct 2012, 19:44 PDT (UT-7)

Classification: Ordinary chondrite (L6)

History: (P. Jenniskens, SETI): A bright fireball was widely observed and photographed from locations in and around the San Francisco Bay Area. The fireball passed the video camera fields of the NASA Cameras for Allsky Meteor Surveillance (CAMS) project. The calculated trajectory had an apparent entry speed at 89 km of 14 km/s. The downward projected path calculated by J. Albers predicted 1 g fragments fell near Bodega, 100 g fragments near Novato and 1 kg fragments near Sonoma. The trajectory was published in the San Francisco Chronicle, which led reader L. Webber of Novato to search her yard on Oct. 20. She remembered hearing the sound of an object hitting the roof of her garage that Wednesday night. At the side of the garage, she found a dense 61.9 g stone (numbered as stone N01), which was strongly attracted to a magnet. During investigation of this potential find, neighbor L. Rivera identified an impact divot on the roof of the Webber residence, shaped and positioned consistent with a meteorite from this fall hitting the roof and landing at the recovery site. A second 65.8 g stone was found in Novato (N02) by Brien Cook on Oct. 22, initially thrown out, but based on the Webber find, retrieved, cut, and recognized as a meteorite on Oct. 24. As of Oct. 30, 2012, four confirmed meteorites had been recovered with a total mass of 314 g. A tally is maintained at the Novato Meteorite Consortium website.

Physical characteristics: The stones are difficult to differentiate from terrestrial rocks. Even the freshly fallen meteorites have a thin brownish and irregular layered fusion crust and irregular dark and light interior. The recovered stones have a rounded shape. They are dense and respond to magnets.

Petrography: (A. Rubin, UCLA): A slice of stone N02 contains ~55 vol.% chondritic clasts and ~45 vol.% shock-darkened material. The fragment examined for petrography was from stone N01. Silicates have weak mosaic extinction. Plagioclase grains range from 50-200 μm. There are numerous troilite veins traversing large portions of the rock (silicate darkening). Chromite grains are fractured; many have troilite veins transecting them. There are a few chromite-plagioclase assemblages. One 12 × 20 μm grain of metallic Cu was found. Some of the troilite grains are polycrystalline. There are some patches where plagioclase has been melted and mobilized. There is localized melting around some of the metal and sulfide grains. There are a few silicate shock melt veins replete with small metal and sulfide blebs. The chondritic clasts have far fewer veins and contain moderately large, highly recrystallized barred olivine and porphyritic olivine-pyroxene chondrules that are well integrated into the matrix. These chondritic clasts are much lighter-colored in transmitted light than the matrix of the rock.

Geochemistry: Olivine Fa24.1±0.4 (n=21); low-Ca pyx Fs20.7±0.5 Wo1.5±0.2 (n=22); Ca-pyx Fs8.0±0.7Wo44.7±0.8 (n=5). The chromite grains (n=11) are somewhat richer in Al2O3 (6.4 wt.%) and MgO (3.4 wt.%) than unshocked ordinary-chondrite chromite, but are more characteristic of shocked and shock-melted chromite grains. Most of the metallic Fe-Ni is taenite with 77.7±5.0 wt.% Fe, 21.4±5.4 wt.% Ni and 0.51±0.18 wt.% Co (n=18). Only one kamacite grain was identified (7.2 wt.% Ni and 1.1 wt.% Co). The Co content of this single grain is intermediate between the ranges for L (0.70-0.95 wt.% Co) and LL (1.42-37.0 wt.% Co) chondrites, but is closer to L. Plagioclase: Ab86.0±0.6Or7.0±0.4 (n=14) is richer in alkalis than typical ordinary-chondrite plagioclase, and probably reflects shock melting. Troilite (n=10) is essentially pure FeS; it contains no detectable Cr, Co or Ni.

Classification: L6 breccia, unweathered W0, and moderately shocked S4.

Specimens: The Webber and Rivera families made 56 g of stone N01 available for study in the Novato meteorite consortium. 20 g of stone N01 is currently preserved at UCLA, unless material from other stones eventually replaces this material as part of the type specimen.

[karmaka]

NOVATO # 5 (24,3 g , 38.1195 N , 122.5720 W , 11/02/2012 ) im MicroXCT-200 scanner

VIDEO-LINK

This movie presents X-ray computed tomographic (CT) data for Novato Sample 5. The first rotation shows surface rendering of the collected CT data, with both the fusion crust and fractures prominent on its exterior. Upon the second rotation, the surface is made transparent to reveal the interior components of the sample presented in a blue-green volume rendering (color bar shown). This visualization is achieved by adjusting the threshold over the nominal full range from 0 to 65,535 that scales with the absorption coefficient of the material. The lower threshold for the volume rendering starts low and is increased to 30,000 to hide the fine grain matrix materials made of low density, low Z elements. The upper threshold was adjusted to 61,671 to provide the best contrast for objects of interest. When the lower threshold is static at 30,000 in the movie, components displayed are metal (FeNi alloy) and troilite (FeS) (shown in green collectively), and finely disseminated FeNi and FeS grains intermingled with silicates (shown in blue). The sample is then cut through the rock virtually showing the individual X-ray CT slices (a total of 790 slices encompass the sample in this slice direction; the CT data was reconstructed into 15.3 micron isotropic voxels). Typical ordinary chondritic textures can be discerned readily, such as chondrules (seen as dark rounded objects in the serial slices, rich in low-Z elements, e.g. O, Mg and Si), as well as metal and troilite grains (bright white, irregularly shaped grains). The X-ray CT imaging was performed at the Center for Molecular and Genomic Imaging at the University of California, Davis, with a MicroXCT-200 scanner (Carl Zeiss X-ray Microscopy, Inc.) The X-ray CT data is rendered using the software Amira 5.4 (VSG Inc.).

NOVATO # 6 (23.7 g , 38.0768 N , 122.5692 W , 11/11/2012 ) im MicroXCT-200 scanner

VIDEO-LINK

This movie presents X-ray computed tomographic (CT) data for Novato Sample 6. The first rotation shows surface rendering of the collected CT data, with both the fusion crust and fractures prominent on its exterior. Upon the second rotation, the surface is made transparent to reveal the interior components of the sample presented in a blue-green volume rendering (color bar shown). This visualization is achieved by adjusting the threshold over the nominal full range from 0 to 65,535 that scales with the absorption coefficient of the material. The lower threshold for the volume rendering starts low and is increased to 28,000 to hide the fine grain matrix materials made of low density, low Z elements. The upper threshold was adjusted to 62,020 to provide the best contrast for objects of interest. When the lower threshold is static at 28,000 in the movie, components displayed are metal (FeNi alloy) and troilite (FeS) (shown in green collectively), and finely disseminated FeNi and FeS grains intermingled with silicates (shown in blue). The sample is then cut through the rock virtually showing the individual X-ray CT slices (a total of 825 slices encompass the sample in this slice direction; the CT data was reconstructed into 20.1 micron isotropic voxels). Typical ordinary chondritic textures can be discerned readily, such as chondrules (seen as dark rounded objects in the serial slices, rich in low-Z elements, e.g. O, Mg and Si), as well as metal and troilite grains (bright white, irregularly shaped grains). The X-ray CT imaging was performed at the Center for Molecular and Genomic Imaging at the University of California, Davis, with a MicroXCT-200 scanner (Carl Zeiss X-ray Microscopy, Inc.) The X-ray CT data is rendered using the software Amira 5.4 (VSG Inc.).

Aufnahmen von Qing-Zhu Yin

[OrgaMet]

... und "coming soon" ein Paper vom Novato Consortium mit vielen netten Details in MAPS ... accepted ist es ... jetzt nimt es seine Zeit  ! schicke Inofs sobald möglich 

Orgamet

[karmaka]

THE AR/AR CHRONOLOGY AND HALOGEN CONTENT
OF THE NOVATO BRECCIATED L6 CHONDRITE

LINK

[OrgaMet]

... und da iss es  ... in MAOS ... from "The Novato Meteorite Consortium": Fall, recovery, and characterization of the Novato L6 chondrite breccia

Abstract

The Novato L6 chondrite fragmental breccia fell in California on 17 October 2012, and was recovered after the Cameras for Allsky Meteor Surveillance (CAMS) project determined the meteor's trajectory between 95 and 46 km altitude. The final fragmentation from 42 to 22 km altitude was exceptionally well documented by digital photographs. The first sample was recovered before rain hit the area. First results from a consortium study of the meteorite's characterization, cosmogenic and radiogenic nuclides, origin, and conditions of the fall are presented. Some meteorites did not retain fusion crust and show evidence of spallation. Before entry, the meteoroid was 35 ± 5 cm in diameter (mass 80 ± 35 kg) with a cosmic-ray exposure age of 9 ± 1 Ma, if it had a one-stage exposure history. A two-stage exposure history is more likely, with lower shielding in the last few Ma. Thermoluminescence data suggest a collision event within the last ∼0.1 Ma. Novato probably belonged to the class of shocked L chondrites that have a common shock age of 470 Ma, based on the U,Th-He age of 420 ± 220 Ma. The measured orbits of Novato, Jesenice, and Innisfree are consistent with a proposed origin of these shocked L chondrites in the Gefion asteroid family, perhaps directly via the 5:2 mean-motion resonance with Jupiter. Novato experienced a stronger compaction than did other L6 chondrites of shock-stage S4. Despite this, a freshly broken surface shows a wide range of organic compounds.

Viel Spass, Orgamet