2008 TC3

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In Sudan (2008), this map shows the ground path of the meteoroid; red line is the path, terminating where it would have hit the ground; green line is the infrasound detection of the explosion; orange crosshairs show METEOSAT IR fireball location; predicted altitudes are listed; exact path and fireball altitude not confirmed

2008 TC3 (Catalina Sky Survey temporary designation 8TA9D69) was a meteoroid 2 to 5 meters (7 to 16 ft) in diameter and weighting 80 tonnes,[1] that entered Earth's atmosphere on October 7, 2008, at 02:46 UTC (05:46 local time).[2] The meteoroid was notable as the first such body to be observed and tracked prior to reaching Earth.[3] It exploded an estimated 37 kilometers (23 mi) above the Nubian Desert in Sudan. A search of the impact zone that began on December 2008 turned up 10.5 kilograms (23 lb) of meteorites in 600 fragments, which are surviving pieces of the meteoroid. The meteorites are of a rare type known as ureilites, which contain, among other minerals, nanodiamonds.[4][5][6]

Contents

[edit] Discovery

The meteoroid was discovered by Richard A. Kowalski at the Catalina Sky Survey (CSS) 1.5-meter telescope at Mount Lemmon, north of Tucson, Arizona, USA, on October 6, 06:39 UTC, about 20 hours before the impact.[7][8][9]

The meteoroid was notable as the first such body to be observed and tracked prior to reaching Earth.[3] The process of detecting and tracking a near-Earth object, an effort sometimes referred to as Spaceguard, was put to the test. In total, 586 astrometric and almost as many photometric observations were performed by 27 amateur and professional observers in less than 19 hours and reported to the Minor Planet Center, which issued 25 Minor Planet Electronic Circulars with new orbit solutions in eleven hours as observations poured in. On October 7, 01:49 UTC,[9] the meteoroid entered the shadow of the Earth which made further observations impossible.

Impact predictions were performed by University of Pisa's CLOMON 2 semi-automatic monitoring system[10][11] as well as Jet Propulsion Laboratory's Sentry system. Spectral observations that were performed by astronomers at the 4.2-meter William Herschel Telescope at La Palma, Canary Islands are consistent with either a C-type or M-type asteroid.

[edit] Explosion

Meteosat 8/EUMETSAT infrared image of the explosion

The object is confirmed to have entered Earth's atmosphere as a meteor above northern Sudan at a velocity of 12.8 kilometres per second (29,000 mph). Estimated trajectory has the object coming out of the western sky at an azimuth of 281 degrees, and an altitude angle of 19 degrees to the local horizon.

It exploded tens of kilometers above the ground with the energy of 0.9 to 2.1 kilotons of TNT, causing a large fireball or bolide[12] in the early morning sky. Very few people inhabit the remote area of the Nubian Desert where the explosion took place; The Times, however, reported that the meteoroid's "light was so intense that it lit up the sky like a full moon and an airliner 1,400 km (870 mi) away reported seeing the bright flash."[13] A webcam captured the flash lighting up El-Gouna beach 725 kilometres north (see this webcam frame).[14] A low-resolution image of the explosion was captured by the weather satellite Meteosat 8.[15] The Meteosat images place the fireball at 21°00′N 32°09′E / 21.00°N 32.15°E / 21.00; 32.15 (2008 TC3 fireball).[16] Infrasound detector arrays in Kenya also detected a sound wave from the direction of the expected impact corresponding to energy of 1.1 to 2.1 kilotons of TNT.[17] Meteoroids of this size hit Earth about two or three times a year.[18]

The trajectory showed intersection with Earth's surface at roughly 20°18′N 33°30′E / 20.3°N 33.5°E / 20.3; 33.5 (2008 TC3 projected impact)[19] though the object was expected to break up perhaps 100–200 kilometers (62–120 mi) west as it descended, somewhat east of the Nile River, and about 100 kilometers (62 mi) south of the Egypt–Sudan border.

According to U.S. government sources[20][21] U.S. satellites detected the impact at 02:45:40 UT, with the initial detection at 20°54′N 31°24′E / 20.9°N 31.4°E / 20.9; 31.4 (2008 TC3 initial detection) at 65.4 kilometers (40.6 mi; 35.3 nmi) altitude and final explosion at 20°48′N 32°12′E / 20.8°N 32.2°E / 20.8; 32.2 (2008 TC3 final explosion) at 37 kilometers (23 mi; 20 nmi) altitude. These images have not been publicly released.

  • EUMETSAT fireball images

  • Meteosat 8 / EUMETSAT visual image of first light flare from 2008 TC3 with lat/long reference

  • Meteosat 8 / EUMETSAT IR image of main fireball from 2008 TC3

  • Meteosat images combined, showing offset from first light flare to main IR flare

[edit] Recovered fragments (Almahata Sitta meteorite)

2008 TC3 fragment found on Feb. 28, 2009 by Peter Jenniskens, with help from students and staff of the University of Khartoum. Nubian Desert, Sudan.

[edit] Search

A search of the impact zone that began on December 6, 2008, turned up 10.5 kilograms (23 lb) of rock in some 600 fragments. These meteorites are collectively named Almahata Sitta,[22] which means "Station Six"[23] in Arabic and is a train station between Wadi Halfa and Khartoum, Sudan. This search was led by Peter Jenniskens from the SETI Institute, California and Muawia Shaddad of the University of Khartoum in Sudan and carried out with collaboration of students and staff of the University of Khartoum. The first 15 meteorites were found in the first three days of the search. Numerous witness were interviewed, and the search was guided with a search grid and specific target area produced by NASA's Jet Propulsion Laboratory in Pasadena, California.[24][25][26][27][28] While fragments have been found before from fireballs seen in the sky, this was the first time fragments had been found from an object that was previously tracked in outer space before hitting Earth.[24]

[edit] Analysis

Samples of the Almahata Sitta meteorite were sent for analysis to a consortium of researchers led by Jenniskens, the Almahata Sitta consortium, including NASA Ames in California, the Johnson Space Center in Houston, the Carnegie Institution of Washington, and Fordham University in New York City. The first sample measured was an anomalous ultra-fine-grained porous polymict ureilite achondrite, with large carbonaceous grains. Reflectance spectra of the meteorite, combined with the astronomical observations, identified asteroid 2008 TC3 as an F-type asteroid class. These fragile anomalous dark carbon-rich ureilites are now firmly linked to the group of F-class asteroids.[6] Amino acids have been found on the meteorite.[29]

[edit] Full circle

Richard Kowalski, who discovered the object, received a tiny fragment of Almahatta Sitta, a gift from friends and well-wishers on the Minor Planet Mailing List, which Kowalski founded in order to help connect professional and amateur astronomers.[30]

[edit] See also

[edit] References

[edit] Notes

  1. ^ "80-Ton Asteroid's Impact Recorded". BBC News. 2009-03-25. http://news.bbc.co.uk/2/hi/uk_news/northern_ireland/7964309.stm. 
  2. ^ Plait, Phil (2008-10-06). "Incoming!!!". Bad Astronomy. http://blogs.discovermagazine.com/badastronomy/2008/10/06/incoming-2/. Retrieved 2008-10-08. 
  3. ^ a b Roylance, Frank (2008-10-07). "Predicted meteor may have been sighted". MarylandWeather. http://weblogs.marylandweather.com/2008/10/predicted_meteor_may_have_been.html. Retrieved 2008-10-08. 
  4. ^ Chang, Kenneth (2009-03-25). "Recovered Pieces of Asteroid Hold Clues to Early History". New York Times. http://www.nytimes.com/2009/03/26/science/space/26asteroid.html?ref=us. Retrieved 2009-03-26. (registration required)
  5. ^ Borenstein, Seth (2009-03-26). "Astronomers catch a shooting star for 1st time". The Associated Press. ABC news. http://abcnews.go.com/Technology/Space/WireStory?id=7175837&page=2. Retrieved 2009-09-15. [dead link]
  6. ^ a b P. Jenniskens et. al. (2009-03-26). "The impact and recovery of asteroid 2008 TC3". Nature 458 (7237): 485–488. Bibcode 2009Natur.458..485J. doi:10.1038/nature07920. PMID 19325630. Archived from the original on 2009-06-01. http://www.nature.com/nature/journal/v458/n7237/abs/nature07920.html. Retrieved 2009-04-04.  Published in Letters to Nature
  7. ^ Williams, Gareth V. (2008-10-06). "MPEC 2008-T50". Minor Planet Center. http://www.cfa.harvard.edu/mpec/K08/K08T50.html. Retrieved 2008-10-08. 
  8. ^ Huntington, Jenny (2008-10-07). "Small Asteroid Enters Earth’s Atmosphere". eFluxMedia. http://www.efluxmedia.com/news_Small_Asteroid_Enters_Earths_Atmosphere_26024.html. Retrieved 2008-10-08. 
  9. ^ a b "Asteroid 2008 TC3 Strikes Earth: Predictions and Observations Agree". NASA. 2008-11-04. http://neo.jpl.nasa.gov/news/2008tc3.html. Retrieved 2009-06-18. 
  10. ^ "NEODys Main Risk Page". http://newton.dm.unipi.it/neodys/. Retrieved 2008-10-08. 
  11. ^ "NEODys 2008 TC3 page". http://newton.dm.unipi.it/cgi-bin/neodys/neoibo?objects:2008TC3;main. Retrieved 2008-10-08. 
  12. ^ "Astronomers predict shooting star over Sudan from space boulder". AFP. http://afp.google.com/article/ALeqM5jOHHF4wcyteiUj5AlJP69dIMb0yA. Retrieved 2008-10-08. 
  13. ^ Simon, Paul (2008-10-08). "Weather Eye: NASA spots asteroid before annihilation". London: timesonline.co.uk. http://www.timesonline.co.uk/tol/news/weather/article4902427.ece. Retrieved 2008-10-08. 
  14. ^ Javaux, Gilbert. "P.G.J.- 2008 TC3... Première détection d'un astéroïde avant son impact sur Terre" (in French). http://pagesperso-orange.fr/pgj/2008_TC3.htm. Retrieved 2009-09-15. "Une webcam de surveillance, située sur la plage de la Mer Rouge à El Gouna en Egypte, a enregistré indirectement le flash de l'explosion qui s'est produit à environ 725 km plus au sud" 
  15. ^ "ASTEROID IMPACT". SpaceWeather.com. 2008-10-08. http://www.spaceweather.com/archive.php?view=1&day=08&month=10&year=2008. Retrieved 2008-10-08. 
  16. ^ "m8 HRV 200810070245". 2008-10-08. http://www.eumetsat.int/groups/ops/documents/image/img_asteroid_impact_hrv.jpg. Retrieved 2008-10-08. 
  17. ^ "Impact of Asteroid 2008 TC3 Confirmed". NASA Near Earth Object Program. 2008-10-07. http://neo.jpl.nasa.gov/news/news160.html. Retrieved 2008-10-08. 
  18. ^ Borenstein, Seth (2008-10-06). "Small Asteroid Headed for Light Show Over Africa". The Associated Press. ABC News. http://abcnews.go.com/Technology/wireStory?id=5968166. Retrieved 2009-09-15. [dead link]
  19. ^ "Mike" (2008-10-06). "Very near NEO Meteoroid impact!". MKVH.de. http://mkvh.de/ast/serendipity/index.php?/archives/9-Very-near-NEO-Meteoroid-impact-!.html. [dead link]
  20. ^ "Asteroid Update". spaceweather.com. 2008-10-15. http://www.spaceweather.com/archive.php?month=10&day=15&year=2008&view=view. Retrieved 2008-10-18. 
  21. ^ "US Gov 28-2". US Gov. 2008-10-15. http://aquarid.physics.uwo.ca/~pbrown/usaf/usg282.txt. Retrieved 2008-10-18. 
  22. ^ Almahata Sitta meteorite on Meteoritical Bulletin Database
  23. ^ "Station Nr. 6. - Nubian Desert". Panoramio. 2008-04-16. Archived from the original on 2009-06-17. http://www.panoramio.com/photo/9417877. Retrieved 2009-06-15. 
  24. ^ a b "NASA Team Finds Riches in Meteorite Treasure Hunt". NASA. 2009-03-27. http://www.nasa.gov/topics/solarsystem/features/asteroid_treasure_hunt.html. Retrieved 2009-04-05. 
  25. ^ “Found: Pieces of meteorite spotted before impact”, New Scientist, News Brief, Issue 2697, p. 15, 2009 February 25
  26. ^ “First tracked space rock recovered after impact”, New Scientist, online blog article re Space, 2009 February 19
  27. ^ newscientist.com Meteorite hunters 'strike gold' in Sudan [photos], 25 Mar 2009. Accessed 2009-04-04. Archived 2009-06-01.
  28. ^ Kwok, Roberta (2009), p. 401.
  29. ^ http://www.space.com/scienceastronomy/asteroid-collision-meteoroid-amino-acids-life-101215.html
  30. ^ planetary.org A piece of an asteroid returns to the telescope that discovered it, 21 Sep 2009. Accessed 2009-10-07.

[edit] Bibliography

  • Jenniskens, P.; et al. (2009), "The impact and recovery of asteroid 2008 TC3", Nature, Letters, Vol. 458, pp. 485–488, 2009 March 26, with supplemental online material; and front cover photo of magazine issue of one of the fragments.
  • Kwok, Roberta (2009), "The Rock That Fell to Earth", Nature, News Feature, Vol. 458, pp. 401–403, 2009 March 26.

[edit] External links

External images
An image of 2008 TC3
Animation of 2008 TC3
Smoky trail (spaceweather.com November 8, 2008)
Wikimedia Commons has media related to: 2008 TC3

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