Tagish Lake meteorite
Encyclopedia
The Tagish Lake meteorite fell at 16:43 p.m. on 18 January 2000 in the Tagish Lake
area in southwestern Yukon
, Canada
.
Fragments of the Tagish Lake meteorite
landed upon the Earth
on January 18, 2000 at 16:43 UT (08:43 local time in Yukon) after a large meteoroid exploded in the upper atmosphere at altitudes between 50 and 30 km with an estimated total energy release of about 1.7 kilotons. Following the reported sighting of a fireball in the in southern Yukon
and northern British Columbia
, Canada
, more than 500 fragments of the meteorite were collected from the lake's frozen surface. Post-event atmospheric photographs of the trail left by the associated fireball and U.S. Department of Defense satellite information yielded the meteor trajectory. Most of the stony, carbonaceous
fragments landed on the Taku Arm of the lake, coming to rest on the lake's frozen surface. The passage of the fireball and the high-altitude explosion set off a wide array of satellite
sensors as well as seismographs.
s in weight before it entered the Earth's atmosphere. However, it is estimated that only 1.3 tonnes remained after ablation
in the upper atmosphere and several fragmentation events, meaning that around 97% of the meteorite had vaporised, mainly becoming stratospheric dust that was seen as noctilucent clouds to the northwest of Edmonton
at sunset, some 12 hours after the event. Of the 1.3 tonnes of fragmented rock, somewhat over 10 kg (about 1%) was found and collected.
, type C2 ungrouped. The pieces of the Tagish Lake meteorite are dark grey to almost black in color with small light-colored inclusions, and a maximum size of ~2.3 kg. Except for a greyish fusion crust, the meteorites have the visual appearance of a charcoal briquette
. The fragments were transported in their frozen state to research facilities after they were collected by a local resident in late January, 2000. Initial studies of these fresh fragments were done in collaboration with researchers from NASA
. Snowfall covered the remaining fragments until April 2000, when a search effort was mounted by researchers from the University of Calgary
and University of Western Ontario
. These later fragments were mostly found to have sunk into the ice by a few cm to more than 20 cm, and had to be collected out of meltwater holes, or cut in icy blocks from the frozen surface of Tagish Lake.
Fragments of the fresh, "pristine" Tagish Lake meteorite totaling more than 850g are currently held in the collections at the Royal Ontario Museum and the University of Alberta
. "Degraded" fragments from the April–May 2000 search are curated mainly at the University of Calgary
and the University of Western Ontario
.
granules that may have been part of the cloud of material that created our solar system
and Sun
. This meteorite shows some similarities to the two most primitive carbonaceous chondrite types, the CI and CM chondrites; it is nevertheless quite distinct from either of them. Tagish Lake has a much lower density than any other type of chondrite and is actually composed of two somewhat different rock types. The major difference between the two lithologies is in the abundance of carbonate minerals; one is poor in carbonates and the other is rich in them.
The complex suite of organic materials in the meteorite probably originally formed in the interstellar medium and/or the solar protoplanetary disk, but was subsequently modified in the meteorites' asteroidal parent bodies.
A portion of the carbon in the Tagish Lake meteorite is contained in what are called nanodiamonds—very tiny diamond grains at most only a few micrometers in size. In fact, Tagish Lake contains more of the nanodiamonds than any other meteorite.
, Yukon
accurately constrained the ground track azimuth from either side. It was found that the Tagish Lake meteorite had a pre-entry Apollo type orbit
that brought it from the outer reaches of the asteroid belt
. Currently, there are only eleven meteorite falls with accurately determined pre-entry orbits, based on photographs or video recordings of the fireballs themselves taken from two or more different angles.
Further study of the reflectance spectrum of the meteorite indicate that it most likely originated from 773 Irmintraud
, a D-type asteroid.
Tagish Lake
Tagish Lake is a lake in the Yukon Territory and northern British Columbia, Canada. The lake is more than long and about 2 km wide.It has two arms, the Taku Arm in the east which is very long and mostly in British Columbia and Windy Arm in the west, mostly in the Yukon. The Klondike Highway runs...
area in southwestern Yukon
Yukon
Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
.
History
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...
landed upon the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
on January 18, 2000 at 16:43 UT (08:43 local time in Yukon) after a large meteoroid exploded in the upper atmosphere at altitudes between 50 and 30 km with an estimated total energy release of about 1.7 kilotons. Following the reported sighting of a fireball in the in southern Yukon
Yukon
Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....
and northern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, more than 500 fragments of the meteorite were collected from the lake's frozen surface. Post-event atmospheric photographs of the trail left by the associated fireball and U.S. Department of Defense satellite information yielded the meteor trajectory. Most of the stony, carbonaceous
Carbonaceous chondrite
Carbonaceous 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...
fragments landed on the Taku Arm of the lake, coming to rest on the lake's frozen surface. The passage of the fireball and the high-altitude explosion set off a wide array of satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
sensors as well as seismographs.
Meteoroid
The Tagish Lake meteoroid is estimated to have been 4 meters in diameter and 56 tonneTonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s in weight before it entered the Earth's atmosphere. However, it is estimated that only 1.3 tonnes remained after ablation
Ablation
Ablation is removal of material from the surface of an object by vaporization, chipping, or other erosive processes. This occurs in spaceflight during ascent and atmospheric reentry, glaciology, medicine, and passive fire protection.-Spaceflight:...
in the upper atmosphere and several fragmentation events, meaning that around 97% of the meteorite had vaporised, mainly becoming stratospheric dust that was seen as noctilucent clouds to the northwest of Edmonton
Edmonton
Edmonton is the capital of the Canadian province of Alberta and is the province's second-largest city. Edmonton is located on the North Saskatchewan River and is the centre of the Edmonton Capital Region, which is surrounded by the central region of the province.The city and its census...
at sunset, some 12 hours after the event. Of the 1.3 tonnes of fragmented rock, somewhat over 10 kg (about 1%) was found and collected.
Specimens
Tagish Lake is classified as a carbonaceous chondriteCarbonaceous chondrite
Carbonaceous 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...
, type C2 ungrouped. The pieces of the Tagish Lake meteorite are dark grey to almost black in color with small light-colored inclusions, and a maximum size of ~2.3 kg. Except for a greyish fusion crust, the meteorites have the visual appearance of a charcoal briquette
Briquette
A briquette is a block of flammable matter used as fuel to start and maintain a fire. Common types of briquettes are charcoal briquettes and biomass briquettes.-Constituents of charcoal briquettes:...
. The fragments were transported in their frozen state to research facilities after they were collected by a local resident in late January, 2000. Initial studies of these fresh fragments were done in collaboration with researchers from 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...
. Snowfall covered the remaining fragments until April 2000, when a search effort was mounted by researchers from the University of Calgary
University of Calgary
The University of Calgary is a public research university located in Calgary, Alberta, Canada. Founded in 1966 the U of C is composed of 14 faculties and more than 85 research institutes and centres.More than 25,000 undergraduate and 5,500 graduate students are currently...
and University of Western Ontario
University of Western Ontario
The University of Western Ontario is a public research university located in London, Ontario, Canada. The university's main campus covers of land, with the Thames River cutting through the eastern portion of the main campus. Western administers its programs through 12 different faculties and...
. These later fragments were mostly found to have sunk into the ice by a few cm to more than 20 cm, and had to be collected out of meltwater holes, or cut in icy blocks from the frozen surface of Tagish Lake.
Fragments of the fresh, "pristine" Tagish Lake meteorite totaling more than 850g are currently held in the collections at the Royal Ontario Museum and the University of Alberta
University of Alberta
The University of Alberta is a public research university located in Edmonton, Alberta, Canada. Founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta and Henry Marshall Tory, its first president, it is widely recognized as one of the best universities in Canada...
. "Degraded" fragments from the April–May 2000 search are curated mainly at the University of Calgary
University of Calgary
The University of Calgary is a public research university located in Calgary, Alberta, Canada. Founded in 1966 the U of C is composed of 14 faculties and more than 85 research institutes and centres.More than 25,000 undergraduate and 5,500 graduate students are currently...
and the University of Western Ontario
University of Western Ontario
The University of Western Ontario is a public research university located in London, Ontario, Canada. The university's main campus covers of land, with the Thames River cutting through the eastern portion of the main campus. Western administers its programs through 12 different faculties and...
.
Analysis and classification
Analyses have shown that Tagish Lake fragments are of a primitive type, containing unchanged stellar dustCosmic dust
Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...
granules that may have been part of the cloud of material that created our solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
and Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. This meteorite shows some similarities to the two most primitive carbonaceous chondrite types, the CI and CM chondrites; it is nevertheless quite distinct from either of them. Tagish Lake has a much lower density than any other type of chondrite and is actually composed of two somewhat different rock types. The major difference between the two lithologies is in the abundance of carbonate minerals; one is poor in carbonates and the other is rich in them.
The complex suite of organic materials in the meteorite probably originally formed in the interstellar medium and/or the solar protoplanetary disk, but was subsequently modified in the meteorites' asteroidal parent bodies.
A portion of the carbon in the Tagish Lake meteorite is contained in what are called nanodiamonds—very tiny diamond grains at most only a few micrometers in size. In fact, Tagish Lake contains more of the nanodiamonds than any other meteorite.
Origin
Based on eyewitness accounts of the fireball caused by the incoming meteorite and on the calibrated photographs of the track which it had left behind and which was visible for about half an hour, scientists have managed to calculate the orbit it followed before it impacted with Earth. Although none of the photographs captured the fireball directly, the fireball path was reconstructed from two calibrated photos taken minutes after the event, giving the entry angle. Eyewitness accounts in the vicinity of WhitehorseWhitehorse, Yukon
Whitehorse is Yukon's capital and largest city . It was incorporated in 1950 and is located at kilometre 1476 on the Alaska Highway in southern Yukon. Whitehorse's downtown and Riverdale areas occupy both shores of the Yukon River, which originates in British Columbia and meets the Bering Sea in...
, Yukon
Yukon
Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....
accurately constrained the ground track azimuth from either side. It was found that the Tagish Lake meteorite had a pre-entry Apollo type orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
that brought it from the outer reaches of the asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
. Currently, there are only eleven meteorite falls with accurately determined pre-entry orbits, based on photographs or video recordings of the fireballs themselves taken from two or more different angles.
Further study of the reflectance spectrum of the meteorite indicate that it most likely originated from 773 Irmintraud
773 Irmintraud
773 Irmintraud is a minor planet that orbits the Sun between the planets Mars and Jupiter. Discovered by German astronomer Franz Kaiser at Heidelberg, Germany, on December 22, 1913, the planetoid was named for Irmtraud, an old German woman's name that appears frequently in old songs and sagas. This...
, a D-type asteroid.
See also
- 773 Irmintraud773 Irmintraud773 Irmintraud is a minor planet that orbits the Sun between the planets Mars and Jupiter. Discovered by German astronomer Franz Kaiser at Heidelberg, Germany, on December 22, 1913, the planetoid was named for Irmtraud, an old German woman's name that appears frequently in old songs and sagas. This...
, the asteroid that the Tagish Lake meteorite most likely came from.