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A chondrule is a round grain found in a chondrite. Chondrules form as molten or partially molten droplets in space before being accreted to their parent asteroids. Because chondrites represent one of the oldest solid materials within the Solar System and are believed to be the building blocks of the planetary system, it follows that an understanding of the formation of chondrules is important to understand the initial development of the planetary system.
A chondrite is a stony (non-metallic) meteorite that has not been modified, by either melting or differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar System accreted to form primitive asteroids. Some such bodies that are captured in the planet's gravity well become the most common type of meteorite by arriving on a trajectory toward the planet's surface. Estimates for their contribution to the total meteorite population vary between 85.7% and 86.2%.
Hedenbergite, CaFeSi2O6, is the iron rich end member of the pyroxene group having a monoclinic crystal system. The mineral is extremely rarely found as a pure substance, and usually has to be synthesized in a lab. It was named in 1819 after M.A. Ludwig Hedenberg, who was the first to define hedenbergite as a mineral. Contact metamorphic rocks high in iron are the primary geologic setting for hedenbergite. This mineral is unique because it can be found in chondrites and skarns (calc–silicate metamorphic rocks). Since it is a member of the pyroxene family, there is a great deal of interest in its importance to general geologic processes.
The LL chondrites are a group of stony meteorites, the least abundant group of the ordinary chondrites, accounting for about 10–11% of observed ordinary-chondrite falls and 8–9% of all meteorite falls. The ordinary chondrites are thought to have originated from three parent asteroids, with the fragments making up the H chondrite, L chondrite and LL chondrite groups respectively. The composition of the Chelyabinsk meteorite is that of a LL chondrite meteorite. The material makeup of Itokawa, the asteroid visited by the Hayabusa spacecraft which landed on it and brought particles back to Earth also proved to be type LL chondrite.
The Great Daylight Fireball was an Earth-grazing fireball that passed within 57 kilometres of Earth's surface at 20:29 UTC on August 10, 1972. It entered Earth's atmosphere at a speed of 15 kilometres per second (9.3 mi/s) in daylight over Utah, United States and passed northwards leaving the atmosphere over Alberta, Canada. It was seen by many people and recorded on film and by space-borne sensors. An eyewitness to the event, located in Missoula, Montana, saw the object pass directly overhead and heard a double sonic boom. The smoke trail lingered in the atmosphere for several minutes.
The Allende meteorite is the largest carbonaceous chondrite ever found on Earth. The fireball was witnessed at 01:05 on February 8, 1969, falling over the Mexican state of Chihuahua. After it broke up in the atmosphere, an extensive search for pieces was conducted and over 2 tonnes were recovered. The availability of large quantities of samples of the scientifically important chondrite class has enabled numerous investigations by many scientists; it is often described as "the best-studied meteorite in history." The Allende meteorite has abundant, large calcium–aluminium-rich inclusions (CAI), which are among the oldest objects formed in the Solar System.
Pultusk is an H5 ordinary chondrite meteorite which fell on 30 January 1868 in Poland near the town of Pułtusk. The event has been known as the stony meteorite shower with the largest number of pieces yet recorded in history. Made up of rocky debris, it consists of pyroxene or olivine chondrules deployed in massive plagioclase. Kamacite is also reported.
CI chondrites, also called C1 chondrites or Ivuna-type carbonaceous chondrites, are a group of rare carbonaceous chondrite, a type of stony meteorite. They are named after the Ivuna meteorite, the type specimen. CI chondrites have been recovered in France, Canada, India, and Tanzania. Their overall chemical composition closely resembles the elemental composition of the Sun, more so than any other type of meteorite.
Neuschwanstein was an enstatite chondrite meteorite that fell to Earth on 6 April 2002 at 22:20:18 GMT near Neuschwanstein Castle, Bavaria, at the Germany–Austria border.
An Earth-grazing fireball is a fireball, a very bright meteor that enters Earth’s atmosphere and leaves again. Some fragments may impact Earth as meteorites, if the meteor starts to break up or explodes in mid-air. These phenomena are then called Earth-grazing meteor processions and bolides. Famous examples of Earth-grazers are the 1972 Great Daylight Fireball and the Meteor Procession of July 20, 1860.
Lodranites are a small group of primitive achondrite meteorites that consists of meteoric iron and silicate minerals. Olivine and pyroxene make up most of the silicate minerals. Like all primitive achondrites lodranites share similarities with chondrites and achondrites.
The Tamdakht meteorite fell near Ouarzazate, Morocco on 20 December 2008 producing a strewn field of approximately 25 kilometres (16 mi) by 2 kilometres (1.2 mi) and two small impact craters, one of about 1.1 metres diameter and 70 centimetres (28 in) depth at 31°09.8′N7°00.9′W and the other of about 20 centimetres (7.9 in) diameter and 10 centimetres (3.9 in) depth at 31°09.9′N07°02.3′W.
The Santa Vitoria do Palmar meteorite was found near the city of Santa Vitoria do Palmar in Brazil in 2003 and 2004.
On 13 October 1990, meteoroid EN131090, with an estimated mass of 44 kg, entered the Earth's atmosphere above Czechoslovakia and Poland and, after a few seconds, returned to space. Observations of such events are quite rare; this was the second recorded using scientific astronomical instruments and the first recorded from two distant positions, which enabled the calculation of several of its orbital characteristics. The encounter with Earth significantly changed its orbit and, to a smaller extent, some of its physical properties.
The Desert Fireball Network (DFN) is a network of cameras in Australia. It is designed to track meteoroids entering the atmosphere, and aid in recovering meteorites. It currently operates 50 autonomous cameras, spread across Western and South Australia, including Nullarbor plain, WA wheatbelt, and South Australian desert, covering an area of 2.5 million km2. The locations of the stations were chosen to facilitate meteorite searching. Starting in 2018, cameras deployed across the world began the first global fireball observatory in association with partner research teams.
Bunburra Rockhole is an anomalous basaltic achondritic meteorite. Originally classified as a eucrite, it was thought to belong to a group of meteorites that originated from the asteroid 4 Vesta, but has since been reclassified based on oxygen and chromium isotopic compositions. It was observed to fall on July 21, 2007, 04:43:56 local time, by the Desert Fireball Network (DFN). Two fragments weighing 150g and 174g were recovered by the DFN at 31°21.0′S, 129°11.4′E in the Nullarbor Desert region, South Australia in November of the same year. This is the first meteorite to be recovered using the Desert Fireball Network observatory.
Murrilli (Moo-da-lee) is an ordinary chondrite of subclass type H5. It is the third meteorite to be recovered using the Australia Desert Fireball Network (DFN) camera observatory. It was observed to fall on 27 November 2015 at 9:15pm local time in South Australia, and recovered by the DFN team on 31 December 2015 from Lake Eyre. As this region is a salt lake, the 1.68 kg rock punched a hole through the ground and was found 0.43 m below the surface. It was recovered 218m from the predicted fall line location.
Dingle Dell is a 1.15 kg ordinary chondrite of subclass L/LL5, and the fourth meteorite to be recovered by the Desert Fireball Network camera observatory. It fell in the Morawa region of Western Australia on 31 October 2016 8:05 pm local time, and was recovered less than a week later, on the morning of 7 November, in a paddock at Dingle Dell farm. Given the rapid turnaround for meteorite recovery and a lack of rainfall between fall date and find date, the rock is in pristine condition and shows no evidence of terrestrial weathering (W0). This particular meteorite fall demonstrates the proficiency of the DFN as a sample recovery tool for meteoritics.
Asteroidal water is water or water precursor deposits such as hydroxide (OH−) that exist in asteroids. The "snow line" of the Solar System lies outside of the main asteroid belt, and the majority of water is expected in minor planets. Nevertheless, a significant amount of water is also found inside the snow line, including in near-earth objects (NEOs).
CM chondrites are a group of chondritic meteorites which resemble their type specimen, the Mighei meteorite. The CM is the most commonly recovered group of the 'carbonaceous chondrite' class of meteorites, though all are rarer in collections than ordinary chondrites.
References
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Dyl, Kathryn A.; Benedix, Gretchen K.; Bland, Phil A.; Friedrich, Jon M.; Spurný, Pavel; Towner, Martin C.; O'Keefe, Mary Claire; Howard, Kieren; Greenwood, Richard (2016-03-01). "Characterization of Mason Gully (H5): The second recovered fall from the Desert Fireball Network". Meteoritics & Planetary Science. 51 (3): 596–613. Bibcode:2016M&PS...51..596D. doi: 10.1111/maps.12605 . ISSN 1945-5100.
- 1 2 3 4 5 6 7 8 9 10 11 12 Towner, M. C.; Bland, P. A.; Spurný, P.; Benedix, G. K.; Dyl, K.; Greenwood, R. C.; Gibson, J.; Franchi, I. A.; Shrbený, L. (2011-09-01). "Mason Gully: The Second Meteorite Recovered by the Desert Fireball Network". Meteoritics and Planetary Science Supplement. 74: 5124. Bibcode:2011M&PSA..74.5124T.
- 1 2 3 4 5 6 7 8 9 "Meteoritical Bulletin: Entry for Mason Gully". www.lpi.usra.edu. Retrieved 2017-06-06.
- 1 2 3 "Meteoritical Bulletin: Recommended classifications". www.lpi.usra.edu. Retrieved 2017-06-06.
- 1 2 3 P., Spurny; Phil, Bland; L., Shrbeny; Martin, Towner; J., Borovicka; A., Bevan; D., Vaughan (2011). "The Mason Gully meteorite fall in SW Australia: fireball trajectory and orbit from photographic records". Meteoritics and Planetary Science Supplement. 46. WILEY-BLACKWELL: A220. Bibcode:2011M&PSA..74.5101S.
- 1 2 3 4 5 6 7 Spurny, P.; Bland, P. A.; Borovicka, J.; Towner, M. C.; Shrbeny, L.; Bevan, A. W. R.; Vaughan, D. (2012-05-01). The Mason Gully Meteorite Fall in SW Australia: Fireball Trajectory, Luminosity, Dynamics, Orbit and Impact Position from Photographic Records. Asteroids, Comets, Meteors 2012. Vol. 1667. p. 6369. Bibcode:2012LPICo1667.6369S.
- ↑ Benedix, Gretchen K.; Lauretta, Dante S.; McCoy, Timothy J. (2005-11-01). "Thermodynamic constraints on the formation conditions of winonaites and silicate-bearing IAB irons". Geochimica et Cosmochimica Acta. 69 (21): 5123–5131. Bibcode:2005GeCoA..69.5123B. doi:10.1016/j.gca.2005.03.048.