Publications

CALL FOR PAPERS (EXTENDED DEADLINE FEBRUARY 9, 2010):
Meteoritics and Planetary Science has agreed to issue a special issue on the impact and recovery of 2008 TC3. Papers received before January 9 will be bundled [Once you are ready to submit, please register, then go to "author center", and select "2008 TC3" under special issues when submitting the manuscript].

Papers submitted for this special issue (update: 2010 Jan 02):

• Sandford et al. "The Mid-Infrared Transmission Spectra of Multiple Stones from the Almahata Sitta Meteorite" [MAPS-1257]
• Jenniskens et al. - "2008TC3 and the search for the Ureilite Parent Body" [MAPS-1267]
• Glavin et al. - "Extraterrestrial amino acids in the Almahata Sitta meteorite"
• Hiroi et al. - "Bidirectional visible-NIR and biconical FT-IR reflectance spectra of Almahata Sitta metoerite samples" [MAPS-1278]
• Rumble et al. - "The oxygen isotope composition of Almahata Sitta" [MAPS-1268]
• Friedrich et al. - "The elemental composition of Almahata Sitta" [MAPS-1270]
• Welten et al. - "Cosmic nuclides in Almahata Sitta ureilite: Cosmic-ray exposure age, pre-atmospheric mass and bulk density of asteroid 2008 TC3" [MAPS-1277]
• Sabbah et al. - "Polycyclic Aromatic Hydrocarbons in asteroid 2008 TC3: the identification of a foreign H5 chondrite clast" [MAPS-1271]
• Murty et al. - "Noble gases and nitrogen in the Almahata Sitta ureilite" [MAPS-1282]
• Kohout et al. - "Homogeneity of asteroid 2008 TC3 (Almahata Sitta meteorites) revealed through magnetic susceptibility measurement"
• Shaddad et al. - "The recovery of asteroid 2008 TC3" [MAPS-1296]

Papers in preperation for this special issue (update: 2010 Jan 25):

• Scheirich et al. - "The rotation and orientation of asteroid 2008 TC3"
• Zolensky et al. - "The petrography of asteroid 2008 TC3"
• Taricco et al. - "Gamma ray isotope studies of Almahata Sitta"
• Hoffmann et al. - "Magnetic properties of Almahata Sitta"
• Herrin et al. - "Evidence for smelting in the Almahata Sitta ureilite"
• Chesley et al. - "Trajectory and orbit of 2008 TC3"
• Steele et al. - "Carbon in Almahata Sitta"
• Ott et al. - "A nobel gas study of two stones from the Almahata Sitta meteorite"
• Kozubal et al. - "Photometric observations of Earth-impacting asteroid 2008 TC3"
• Qin et al. - "Chrome isotopes in Almahata Sitta"

Meetings

Meteoroids 2010 (May 24-28, 2010)
An international conference on minor bodies in the solar system in Breckenridge, Colorado, will offer an opportunity to discuss results from the study of 2008 TC3 and its recovered fragments.
Abstracts are due January 15

41st LUNAR AND PLANETARY SCIENCE CONFERENCE (March 1-5, 2010)
Papers on 2008 TC3 will be discussed at the LPSC meeting in The Woodlands, Texas in March. A special session "Ureilite asteroids: Insights from Almahata Sitta" will be held on Tuesday March 2 at 1:30 pm (Waterway Ballroom 1). A poster session will follow that day at 7:00 pm in the Town Center Exhibit Area.
[Special Session program] ; [Program poster session]

2008 TC3 WORKSHOP (DECEMBER 5-15, 2009):
A workshop was held at the Physics Department of Khartoum University, Sudan, on December 6 - 7 of 2009, one year after the first find, to discuss the results from the analysis of 2008 TC3's impact and recovered remnants. Immediately following, the Nubian Desert site was re-visited for an additional search to extend the range of meteorites recovered, after which some of Sudan's amazing archeological sites were visited on the way back (Dec 8-15). The workshop website is at:
[Scientific program, abstracts, pictures]

AAS / DPS MEETING (OCTOBER 4-9)
A topical session on the impact and recovery of 2008 TC3 was held at the DPS meeting in Puerto Rico on October 4-9, 2009, during the one-year aniversary of the fall.
[Program Topical Session]; [Abstracts]

Almahata Sitta Consortium

M. Shaddad	U. of Khartoum	Meteorite recovery	# all samples
P. Jenniskens	SETI Institute	Meteorite recovery	# selected samples

M. Zolensky	NASA/JSC	Petrograpy		#1,4,7,15,25,27,47,A100,2,16,33,41,22,27,S138
N. Kita		U. Wisconsin-Madison	SEM, EPMA, SIMS	#44,36,51,54
I. Hope		LLNL		TEM,SEM			#4,7

D. Rumble	Carnegie Inst.	Oxygen isotopes		#4,7,47,15,25,27,36,44,49,51,54

J. Friedman	Fordham U.	Bulk chemistry (ICPMS)	#4,7,47,15
S. Wolf		Indiana St. Un.	bulk chemistry (ICPMS)	#4,7,47,15
J. Kucera	Nuclear Phys. Inst., Czech Rep.	multi-element analysis	-.-

T. Hiroi	Brown U.	Reflection spectroscopy	#4,7,25,27,47,19,32,36,44,50,51
S. Sandford	NASA/Ames	IR spectroscopy		#4,7,15,19,24,25,27,28,29,
							#31,32,34,36,37,39,42,44,46
 							#47,48,49,50,51,52,53,54 

A. Steele	Carnegie Inst.	Raman spectroscopy	#7,#4
A. Morrow	Stanford U.	PAHs			#1,4,7,15,25,27,47[....]
D. Glavin	NASA/Goddard	amino acids		#4

K. Welten	UC Berkeley	Cosmic radio isotopes	#4, 47,1,15,36,44,25,A100
C. Taricco	Turin, Italy	gamma-ray spectr.	#15

R. Weiler	Switzerland	Nobel gasses		#4, 47
S. Murty	Navrangpura, India	Nobel gasses	#36, 44
U. Ott		MPI fur Chemie, Mainz	Nobel gasses 	#1,47
K. Nagao	University of Tokyo	Nobel gasses	#1,47
B. Marty	CRPG/CNRS, Nancy	Nobel gasses	#1,47

V. Hoffmann	Univ. Muenich	magnetic properties	#4,39

G. Patesi	Univ. Firenze	cathodoluminescence	-.- [needs large samples]
H. Chennaoui	Hassan II Univ.	cathodoluminescence	-.-

S. Larson	Catalina Sky Survey	2008TC3: discovery
S. Chesley	NASA/JPL		2008TC3: orbit, impact trajectory
P. Chodas	NASA/JPL		2008TC3: orbit, impact  
A. Fitzimmons	Queens U. Belfast	2008TC3: spectroscopy
R. Dantowitz	Clay Center Obs.	2008TC3: imaging
P. Pravec	Ondrejov Observatory 	2008TC3: rotation curve
P. Scheirich	Ondrejov Observatory	2008TC3: shape model
J. Borovicka	Ondrejov Observatory	Impact: Meteosat 8 satelite data
M. Boslough	Sandia Nat. Lab.	Impact: USAF satellite data
P. Brown	U. Western Ontario	Impact: infrasound
W. Edwards	U. Western Ontario	Impact: dark flight
D. ReVelle	Los Alamos Nat. Lab.	Impact: modeling
O. Popova	Inst. Geosc. Moscow	Impact: modeling
J. Vaubaillon	IMCCE, Paris		Big picture: orbital dynamics
R. Binzel	MIT			Big picture: asteroid taxonomy

OVERVIEW OF RESEARCH ON ALMAHATA SITTA SAMPLES: 

Number:	Density (g/cm3)	Spectral shape  Albedo	Oxygen isotopes	Petr.	Min. 	Texture;Notes
 	[1]		[2]		[3]	[4]		[5]	[6]	[7]
Non-ureilite samples of 2008 TC3:
#16:	3.42+/-0.12	-.-		-.-	-.-		n	-.-
#22:	3.26+/-0.36	-.-		-.-	-.-		n	-.-
#25:	-.-		strong pyroxene 0.23	-.-		y	Prx	H5 chondrite 
#33:	4.85+/-0.03	-.-		-.-	-.-		n	-.-	
#41:	3.16+/-0.02	-.-		-.-	-.-		n	-.-
#A100:	-.-		-.-		-.-	-.-		y	-.-	L4 chondrite

Ureilite samples: 
#1:	1.77+/-0.17	-.-		-.-	-.-		y	-.-	layered
#4:	2.55+/-0.08	flat spectrum	0.10	low 17 low 18	y	Oli	scruffy; *) **)
#7:	-.-		weak pyroxene	0.16	high 17 high 18	y	Oli	layered, porous
#13: 	-.-		-.-		-.-	-.-		n	-.-	full crust, oriented
#15:	3.11+/-0.02	-.-		-.-	-.-		y	Mix	; gamma-ray 
#19: 	-.-		-.-		-.-	-.-		n	Oli	(crumbs)
#22:	3.26+/-0.13	-.-		-.-	-.-		n	-.-	[no sample yet]
#24: 	-.-		-.-		-.-	-.-		n	Oli	(crumbs)
#27:	2.83+/-0.15	weak pyroxene	0.10	-.-		y	Oli	flaky 
#28:	2.57+/-0.04	-.-		-.-	-.-		n	Oli	; weak band depth	
#29: 	-.-		-.-		-.-	-.-		n	Mix	(crumbs)
#31: 	-.-		-.-		-.-	-.-		n	Prx	(crumbs)
#32:	2.98+/-0.14	-.-		-.-	-.-		n	Oli	(crumbs)
#34: 	-.-		-.-		-.-	-.-		n	Oli	(crumbs)
#36:	2.67+/-0.02	-.-		-.-	-.-		n	Mix	fine grained 	**)
#37: 	-.-		-.-		-.-	-.-		n	Oli	(crumbs)
#39: 	-.-		-.-		-.-	-.-		n	Oli	single fragment
#41:	3.16+/-0.02	-.-		-.-	-.-		n	-.-	finegrained
#42: 	-.-		-.-		-.-	-.-		n	Mix	(crumbs)
#44: 	-.-		-.-		-.-	-.-		n	Oli	fragments only **)
#46: 	-.-		-.-		-.-	-.-		n	Oli	(crumbs)
#47:	2.96+/-0.05	weak pyroxene	0.11	high 17 low 18	y	Oli	weathered pieces **)
#48: 	-.-		-.-		-.-	-.-		n	Oli	(crumbs)
#49:	2.55+/-0.26	-.-		-.-	-.-		n	Oli	(crumbs)
#50:	2.37+/-0.17	-.-		-.-	-.-		n	Oli	(crumbs)
#51:	2.70+/-0.06	-.-		-.-	-.-		n	Prx	(crumbs)
#52: 	-.-		-.-		-.-	-.-		n	Mix	(crumbs)
#53: 	-.-		-.-		-.-	-.-		n	Oli	(crumbs)
#54:	2.59+/-0.16	-.-		-.-	-.-		n	Oli	(crumbs)
#S138:	-.-		-.-		-.-	-.-		y	Oli	-.-	

Ref.:
*) amino acid analyis
**) cosmic ray and nobel gasses

[1] Densities measured by Jenniskens using sand method (Shaddad et al., 2010)
[2] From data by Hiroi et al. (2010)
[3] From data by Hiroi et al. (2010)
[4] From data by Rumble et al. (2010)
[5] Petrographic study done, from data by Zolensky et al. (2010)
[6] Dominant mineral type determined by mid-IR spectroscopy, data by Sandford et al. (2010)
[7] Typing from petrography by Zolensky; Descriptions from photographs by Jenniskens

The recovery of asteroid 2008 TC3

[Pictures from NASA Media Telecon March 25, 2008]
[Audio from NASA Media Telecon (11 MByte)]

March 26 - In the March 26 issue of Nature magazine, it is reported that fragments of asteroid 2008 TC3 have been recovered in a search expedition led by Dr. Muawia Shaddad of the Physics Department of the Faculty of Sciences of the University of Khartoum. Under the guidance of outside expert meteor astronomer Dr. Peter Jenniskens of the SETI Institute and NASA Ames Research Center in California, the team searched along the projected ground path of the asteroid on December 6-8, 2008. Eye witness interviews suggested no large pieces survived the explosion, so we started looking in the area where small fragments would have fallen. Students were lined up along a kilometer to comb the desert. The first meteorite was found by student Mohammed Alameen just down track from the explosion that turned most of the 80,000 kg sized asteroid into dust. In total, only about 5 kg survived and came out of the explosion with cosmic speed of 12.4 km/s. Because it took long for the larger pieces to be slowed down, they ended up falling 29 km downrange from where the first meteorite was found. Two more expeditions were organized by the University of Khartoum, netting a total of some 280 meteorites. Never before have meteorites been recovered from something exploding this high in the atmosphere. Sure enough, this turns out to be a very unusual meteorite not yet in our collections. It is an anomalous polymic ureilite. By comparing the reflection properties of the meteorite with those of the asteroid in space, we were able to conclude that this was an F-class asteroid. We now know that (some) F-class asteroids have a dark surface because they are made up of a black and porous anomalous kind of ureilite.

[ALL PHOTO's BELOW ARE TO BE CREDITED TO: PETER JENNISKENS/SETI INSTITUTE. CLICK ON IMAGES FOR HIGH-RES VERSION]

- Eye witness Abdel Moniem Magzoub, the station attendant, describes the altitude of the fireball explosion as seen at Station 6 to interviewer Dr. Muawia Shaddad of the University of Khartoum on December 5, 2008. Magzoub was woken by the bright light from the first explosion, sat up, and then saw the fireball briefly continue until the second weaker explosion. A short while later, he heard a sound "doe-doe-doe-doe-doe".

- Some 45 students and staff of the University of Khartoum, and all necessary logistics for transport, eating, and sleeping, were brought to Station 6 in the middle of the Nubian Desert to help find the meteorites. Here they are at Station 6, with their mode of transportation in the background.

- Schematic map of the region, in northern Sudan, with Station 6 and the path of the fireball marked. Image based on Meteosat 8 detection (note: position of the explosion is slightly off due to glancing perspective).

- In order to comb the desert for meteorites, the University of Khartoum students and staff were distributed along a 1 km line, here on the third day of the first search expedition on December 8, 2008. In the green shirt is team leader Dr. Muawia Shaddad, an astronomer with the University of Khartoum.

- The Nubian Desert has rocky plains, interspersed with hills, rocky outcrops and sandy river valleys. The rocky terrain demanded a foot search at relatively close distance between the searchers.

- The first meteorite, now called "Almahata Sitta", was found after only 2 hours of searching by student Mohammed Alameen on December 6, 2008. The search was concentrated in the area where (more common) small fragments were expected to have fallen. The meteorite is handled with aluminum foil to prevent contamination from touching.

- Five more black scruffy looking meteorites like this lager one were found the next day, spread along the asteroid path, which proved that we were picking up meteorites from 2008 TC3.

- The third day, December 8, the students walked 18 kilometers and gradually saw the size of the meteorites increase from small pebbles to chicken egg size, as expected for debris from asteroid 2008 TC3. Here, Muawia Shaddad and Peter Jenniskens are pointing at the meteorite, in the company of several of the University of Khartoum students.

- Each meteorite's location was carefully marked to help study how the asteroid broke during entry. When a meteorite was found, students would wait for Jenniskens or Shaddad to log the location of the find and collect the meteorites. Here, the bus got stuck in the search area, and a meteorite was found when the students departed from the bus. While others helped push the bus free from the sand, a student waited until the meteorite had been officially logged.

- Finding a meteorite was an incredible experience, according to Jenniskens. Here, he finds his first meteorite: one that broke in two druing landing. "For a moment you realise that you are the first person to lay eyes on these rocks from space, laying there in the sand much the same as the day they fell on the ground," he says. Every find brought back that euphoric sense of discovery. This picture was taken during the third search on February 28, 2009.

- Peter's second find happend just minutes later when he and his driver were catching up on the line of students and his driver decided to go over a black rock on the desert floor. An adrenaline rush, a call to "stop", and sure enough: another great piece of asteroid 2008 TC3.

Meteosat 8 detected the impact of asteroid 2008 TC3 over northern Sudan, during a 5-second image scan of Earth.

Just before dawn, this luminous train was visible over the area. Photo from a video by Mohamed Elhassan Abdelatif Mahir (Noub NGO), image courtesy Dr. Muawia H. Shaddad (Univ. Karthoum).

Luminous train from a video by Mohamed Elhassan Abdelatif Mahir (Noub NGO), image courtesy Dr. Muawia H. Shaddad (Univ. Karthoum).

November 08 - 2008 TC3 impact train is Astronomy Picture of the Day, in an effort to collect more of such observations. If you observed the fireball or train in the early morning of October 7 over Northern Sudan, please contact:

Dr. Muawia Hamid Shaddad, 
PO Box 114, 
Khartoum Centre, Sudan 
Tel: +249 912 359317; 
e-mail: shaddadmhsh@yahoo.com

Dr. Peter Jenniskens
SETI Institute
515 N. Whisman Road
Mountain View, CA 94043
Tel.: +1-650-8100216
e-mail: pjenniskens@mail.arc.nasa.gov

October 06 - For the first time, a small (2-3 meter sized) asteroid was discovered in space on approach to Earth, just before hitting the Earth. While initially very faint, the close approach made it bright enough (about +14 magnitude) for spectroscopic studies and studies of asteroid lightcurve. This data might be compared to collected samples if a meteorite is recovered. In most cases, this will not be the case because most impacts are over the ocean or difficult terrain on land.

The impact point was calculated with 8 hours warning over northern Sudan in a desert area. The impact was seen by observers on the ground, from an airplane over Tsad, as a flash in video cameras pointed elsewhere, detected by low frequency sound waves (infrasound), and detected as a flash in rapid scanning Meteosat 8 images. No spectroscopic information of the object was obtained.