2008 TC3
Encyclopedia
Meteoroid
A meteoroid is a sand- to boulder-sized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth's atmosphere is called a meteor, or colloquially a shooting star or falling star. If a meteoroid reaches the ground and survives impact, then it is called a meteorite...
2 to 5 m (6.6 to 16.4 ft) in diameter and weighting 80 tonnes, that entered Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
on October 7, 2008, at 02:46 UTC (05:46 local time). The meteoroid was notable as the first such body to be observed and tracked prior to reaching Earth. It exploded an estimated 37 kilometres (23 mi) above the Nubian Desert
Nubian Desert
The Nubian Desert is in the eastern region of the Sahara Desert, spanning approximately 400,000 km² of northeastern Sudan between the Nile and the Red Sea. The arid region, a largely sandstone plateau, has lots of wadis flowing towards the Nile. There is virtually no rainfall in the Nubian,...
in Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
. A search of the impact zone that began on December 2008 turned up 10.5 kilograms (23.1 lb) of meteorite
Meteorite
A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...
s in 600 fragments, which are surviving pieces of the meteoroid. The meteorites are of a rare type known as ureilite
Ureilite
Ureilite is a rare type of stony meteorite that has a unique mineralogical composition very different from that of other stony meteorites. This dark grey or brownish meteorite type is named after the village Novy Urey , Mordovia Republic of Russia, where a meteorite of this type fell on 4 September...
s, which contain, among other minerals, nanodiamonds.
Discovery
The meteoroid was discovered by Richard A. KowalskiRichard A. Kowalski
Richard A. Kowalski is an American astronomer who has discovered numerous asteroids and other near-Earth objects.Kowalski has had a lifelong interest in astronomy with an emphasis on planetary science. As an amateur in Florida during the 1990s he developed an interest in astrometric and...
at the Catalina Sky Survey
Catalina Sky Survey
Catalina Sky Survey is a project to discover comets and asteroids, and to search for Near-Earth objects. More specifically, to search for potentially hazardous asteroids , that may pose a threat of impact.-Mission:...
(CSS) 1.5-meter telescope at Mount Lemmon
Mount Lemmon
Mount Lemmon is in the Santa Catalina Mountains located in the Coronado National Forest north of Tucson, Arizona, United States. It is above sea-level, and receives approximately 180 inches of snow annually. Mount Lemmon was named in honor of botanist Sarah Lemmon, who trekked to the top of...
, north of Tucson, Arizona
Tucson, Arizona
Tucson is a city in and the county seat of Pima County, Arizona, United States. The city is located 118 miles southeast of Phoenix and 60 miles north of the U.S.-Mexico border. The 2010 United States Census puts the city's population at 520,116 with a metropolitan area population at 1,020,200...
, USA, on October 6, 06:39 UTC, about 20 hours before the impact.
The meteoroid was notable as the first such body to be observed and tracked prior to reaching Earth. The process of detecting and tracking a near-Earth object
Near-Earth object
A near-Earth object is a Solar System object whose orbit brings it into close proximity with the Earth. All NEOs have a perihelion distance less than 1.3 AU. They include a few thousand near-Earth asteroids , near-Earth comets, a number of solar-orbiting spacecraft, and meteoroids large enough to...
, an effort sometimes referred to as Spaceguard
Spaceguard
The term Spaceguard loosely refers to a number of efforts to discover and study near-Earth objects . Asteroids are discovered by telescopes which repeatedly survey large areas of sky. Efforts which concentrate on discovering NEOs are considered part of the "Spaceguard Survey," regardless of which...
, 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
Minor Planet Center
The Minor Planet Center operates at the Smithsonian Astrophysical Observatory , which is part of the Center for Astrophysics along with the Harvard College Observatory ....
, which issued 25 Minor Planet Electronic Circulars with new orbit solutions in eleven hours as observations poured in. On October 7, 01:49 UTC, the meteoroid entered the shadow of the Earth which made further observations impossible.
Impact predictions were performed by University of Pisa
University of Pisa
The University of Pisa , located in Pisa, Tuscany, is one of the oldest universities in Italy. It was formally founded on September 3, 1343 by an edict of Pope Clement VI, although there had been lectures on law in Pisa since the 11th century...
's CLOMON 2 semi-automatic monitoring system as well as Jet Propulsion Laboratory's
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
Sentry
Sentry (monitoring system)
Sentry is a highly automated collision monitoring system that continually scans the most current asteroid catalog for possibilities of future impact with Earth over the next 100 years...
system. Spectral observations that were performed by astronomers at the 4.2-meter William Herschel Telescope
William Herschel Telescope
The William Herschel Telescope is a optical/near-infrared reflecting telescope located at the Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands, Spain. The telescope, which is named after William Herschel, is part of the Isaac Newton Group of Telescopes...
at La Palma
La Palma
La Palma is the most north-westerly of the Canary Islands. La Palma has an area of 706 km2 making it the fifth largest of the seven main Canary Islands...
, Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
are consistent with either a C-type
C-type asteroid
C-type asteroids are carbonaceous asteroids. They are the most common variety, forming around 75% of known asteroids, and an even higher percentage in the outer part of the asteroid belt beyond 2.7 AU, which is dominated by this asteroid type...
or M-type asteroid
M-type asteroid
M-type asteroids are asteroids of partially known composition; they are moderately bright . Some, but not all, are made of nickel-iron, either pure or mixed with small amounts of stone. These are thought to be pieces of the metallic core of differentiated asteroids that were fragmented by impacts,...
.
Explosion
METEOR
METEOR is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision...
above northern Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
at a velocity of 12.8 km/s. 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
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
, causing a large fireball or bolide
in the early morning sky. Very few people inhabit the remote area of the Nubian Desert
Nubian Desert
The Nubian Desert is in the eastern region of the Sahara Desert, spanning approximately 400,000 km² of northeastern Sudan between the Nile and the Red Sea. The arid region, a largely sandstone plateau, has lots of wadis flowing towards the Nile. There is virtually no rainfall in the Nubian,...
where the explosion took place; The Times
The Times
The Times is a British daily national newspaper, first published in London in 1785 under the title The Daily Universal Register . The Times and its sister paper The Sunday Times are published by Times Newspapers Limited, a subsidiary since 1981 of News International...
, however, reported that the meteoroid
Meteoroid
A meteoroid is a sand- to boulder-sized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth's atmosphere is called a meteor, or colloquially a shooting star or falling star. If a meteoroid reaches the ground and survives impact, then it is called a meteorite...
's "light was so intense that it lit up the sky like a full moon and an airliner 1400 km (869.9 mi) away reported seeing the bright flash." A webcam captured the flash lighting up El-Gouna
El-Gouna
El Gouna is a tourist resort, developed and owned by Orascom Hotels and Development , dating from about 1990...
beach 725 kilometres north (see this webcam frame). A low-resolution image of the explosion was captured by the weather satellite Meteosat 8
Meteosat 8
Meteosat 8 is a weather satellite, also known as MSG 1. The Meteosat series are operated by EUMETSAT under the Meteosat Transition Programme and the Meteosat Second Generation program. Notable for imaging the first meteor to be predicted to strike the earth, 2008 TC3...
. The Meteosat images place the fireball at 21.00°N 32.15°W. Infrasound
Infrasound
Infrasound is sound that is lower in frequency than 20 Hz or cycles per second, the "normal" limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high...
detector arrays in Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
also detected a sound wave from the direction of the expected impact corresponding to energy of 1.1 to 2.1 kilotons of TNT. Meteoroids of this size hit Earth about two or three times a year.
The trajectory showed intersection with Earth's surface at roughly 20.3°N 33.5°E though the object was expected to break up perhaps 100 – west as it descended, somewhat east of the Nile River, and about 100 kilometres (62.1 mi) south of the Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
–Sudan border.
According to U.S. government sources U.S. satellites detected the impact at 02:45:40 UT, with the initial detection at 20.9°N 31.4°E at 65.4 km (40.6 mi; 35.3 nmi) altitude and final explosion at 20.8°N 32.2°E at 37 km (23 mi; 20 nmi) altitude. These images have not been publicly released.
Recovered fragments (Almahata Sitta meteorite)
Search
A search of the impact zone that began on December 6, 2008, turned up 10.5 kilograms (23.1 lb) of rock in some 600 fragments. These meteorites are collectively named Almahata Sitta, which means "Station Six" in Arabic and is a train station between Wadi HalfaWadi Halfa
Wadi Halfa is a city in the state of Northern, in northern Sudan, on the shores of Lake Nubia . It is the terminus of a rail line from Khartoum and the point where goods are transferred from rail to ferries going down the Lake Nasser...
and Khartoum
Khartoum
Khartoum is the capital and largest city of Sudan and of Khartoum State. It is located at the confluence of the White Nile flowing north from Lake Victoria, and the Blue Nile flowing west from Ethiopia. The location where the two Niles meet is known as "al-Mogran"...
, Sudan. This search was led by Peter Jenniskens
Peter Jenniskens
Petrus Matheus Marie Jenniskens is a Dutch astronomer and a senior research scientist at the Carl Sagan Center of the SETI Institute and at NASA Ames Research Center. He is an expert on meteor showers. Jenniskens is the author of the 790 page book "Meteor Showers and their Parent Comets"...
from the SETI Institute
SETI Institute
The SETI Institute is a not-for-profit organization whose mission is to “explore, understand and explain the origin, nature and prevalence of life in the universe”. SETI stands for the "search for extraterrestrial intelligence". One program is the use of both radio and optical telescopes to search...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and Muawia Shaddad of the University of Khartoum
University of Khartoum
The University of Khartoum ia a multi-campus, co-educational university located in Khartoum. It is the largest and oldest university in Sudan. UofK was founded as Gordon Memorial College in 1902 and established in 1956 when Sudan gained independence...
in Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
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
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
in Pasadena, California
Pasadena, California
Pasadena is a city in Los Angeles County, California, United States. Although famous for hosting the annual Rose Bowl football game and Tournament of Roses Parade, Pasadena is the home to many scientific and cultural institutions, including the California Institute of Technology , the Jet...
. 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.
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 AmesNASA Ames Research Center
The Ames Research Center , is one of the United States of America's National Aeronautics and Space Administration 10 major field centers.The centre is located in Moffett Field in California's Silicon Valley, near the high-tech companies, entrepreneurial ventures, universities, and other...
in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, the Johnson Space Center in Houston, the Carnegie Institution of Washington, and Fordham University
Fordham University
Fordham University is a private, nonprofit, coeducational research university in the United States, with three campuses in and around New York City. It was founded by the Roman Catholic Diocese of New York in 1841 as St...
in New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
. The first sample measured was an anomalous ultra-fine-grained porous polymict
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
ureilite
Ureilite
Ureilite is a rare type of stony meteorite that has a unique mineralogical composition very different from that of other stony meteorites. This dark grey or brownish meteorite type is named after the village Novy Urey , Mordovia Republic of Russia, where a meteorite of this type fell on 4 September...
achondrite
Achondrite
An achondrite is a stony meteorite that does not contain chondrules. It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystallization on or within meteorite parent bodies...
, with large carbonaceous grains. Reflectance spectra of the meteorite, combined with the astronomical observations, identified asteroid 2008 TC3 as an F-type asteroid
F-type asteroid
F-type asteroids are a relatively uncommon type of carbonaceous asteroid, falling into the wider C-group.-Characteristics:Generally similar to the B-type asteroids, but...
class. These fragile anomalous dark carbon-rich ureilite
Ureilite
Ureilite is a rare type of stony meteorite that has a unique mineralogical composition very different from that of other stony meteorites. This dark grey or brownish meteorite type is named after the village Novy Urey , Mordovia Republic of Russia, where a meteorite of this type fell on 4 September...
s are now firmly linked to the group of F-class asteroids. Amino acids have been found on the meteorite.
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.See also
- Carbonaceous chondriteCarbonaceous chondriteCarbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 7 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites...
s - List of notable asteroids
- The Great Daylight 1972 FireballThe Great Daylight 1972 FireballThe Great Daylight 1972 Fireball was an Earth-grazing meteoroid which passed within of the surface of the Earth at 20:29 UTC on August 10, 1972. It entered the Earth's atmosphere in daylight over Utah, United States and passed northwards leaving the atmosphere over Alberta, Canada...
- Impact eventImpact eventAn impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant...
External links
- Remanzacco Observatory photographs of the incoming space rock
- Telescopio Nazionale Galileo photograph of 2008 TC3
- News bulletin from NASA Near Earth Object Program
- The full story of Earth-impacting asteroid by Emily Lakdawalla (The Planetary Society Blog)
- NASA, Near Earth Object Program, November 4, 2008
- Announcement with animation (linked from #PGJ2008TC3)
- (orbits, charts, observation records, fragment analysis)
- Online science newsletter article published March 12, 2009
- BBC article about the asteroid, March 25, 2009
- APOD Astronomy Picture of the DayAstronomy Picture of the DayAstronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
