- 3189 - METEORITES - history in meteorites? Meteorites are pieces of planets that never collected together big enough to become a planet. They just remain scattered around in orbit as asteroids circling the Sun.
- ---------------------- 3189 - METEORITES - history in meteorites?
- “Vesta” is the second-largest meteorite in the asteroid belt, the evidence of its tumultuous past is in two giant scars on its surface. The violence written into Vesta’s surface forged the asteroid belt we know today, now a scattered band of debris and fragmented protoplanets in the middle of our solar system. The Asteroid Belt.
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- The belt was once made up of larger rocky bodies called protoplanets, small building blocks of larger worlds. The early solar system smashed most of these potential planets to pieces, forming the asteroids we see today.
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- Vesta was once such a protoplanet too, giving birth to an entire family of asteroids within the belt. Some fragments of Vesta have since left the belt’s confines. In 2018, one of the small, wandering chunks of Vesta hurtled into Earth’s atmosphere as a fireball, breaking into pieces over a large game reserve in Botswana. That little piece could give us massive insight into the mechanics at work in the early solar system.
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- This meteorite named “Motopi Pan” is small, but has a big story to tell about our solar system’s rich history. Unlike “Ceres“, a surviving protoplanet in the asteroid belt that has been largely untouched since the solar system’s earliest days, Vesta carries a record of two giant impacts, from the solar system that spawned the asteroid belt.
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- Researchers date a crater by counting the smaller craters that have formed on its surface and estimating how long it would take to accumulate those newer craters.
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- The meteorite that landed in Botswana, called Motopi Pan, gives a look back in time at when these violent collisions took place. The first of the two giant impacts happened about 4,230,000,000 years ago.
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- The second giant impact likely happened roughly 3.5 billion years ago. Much later, the Motopi Pan rock itself broke off Vesta in a small collision only about 23 million years ago that possibly formed the Rubria crater, a smaller crater near the two giant basins.
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- Even if researchers can identify the solar system object a meteorite is from, like the Moon or Mars, it’s rare to be able to pinpoint where on those bodies the meteorite material came from.
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- Comparing the Motopi Pan meteorite with another meteorite from Vesta, called “Sariçiçek“, which was found in Turkey in 2015, let the researchers unravel the different histories that rocks on different parts of Vesta must have experienced.
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- The Sariçiçek rock had been through only one of the two heating events that Motopi Pan experienced, giving clues to where on Vesta these rocks originated.
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- The “Dawn” mission gave us a close look at Vesta, learning a lot about the asteroid’s composition and potential history. The spacecraft found evidence that the asteroid probably has ice on parts of its surface.
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- Dawn also gave evidence that Vesta has a distinct core and crust, hints of its past as a protoplanet, even though it’s not spherical like its cousin Ceres, the sole dwarf planet in the inner solar system.
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- The reason it’s not spherical may be due to these large impacts as well as other, smaller ones. Tracing the impact history of Vesta helps build a better view of what the early solar system was like.
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- In June 2018, the “Catalina Sky Survey“, which monitors the skies for asteroids, spotted a small one, dubbed “2018 LA“, that was on track to collide with Earth within hours. Follow-up analyses revealed that the space rock probably came from Vesta, and it entered Earth’s atmosphere as a brilliant fireball over Botswana.
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- When the asteroid fell researchers tracked down security camera footage of the fireball, triangulate where it broke up into pieces, and get access to search the wild game reserve where the fireball fell to Earth. The team eventually found 23 pieces of the meteorite.
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- The team analyzed the chemical compositions of the meteorite to confirm that it came from Vesta. They discovered it had experienced two major heating events, and calculated how long it had been since the giant impacts that heated the rock.
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- They measured the presence of certain chemical isotopes to estimate how recently the rock was blown off Vesta, which led them to pinpoint the crater Rubria as the potential source of this meteorite.
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- Asteroids continue to collide and distribute debris around the solar system to this day. Future meteorites will give us clues to more of the solar system’s history.
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- The June 2, 2018, impact of asteroid 2018 LA over Botswana is only the second asteroid detected in space prior to impacting over land. The data was used to define the spin period and shape of the asteroid.
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- Video observations of the fireball constrain the asteroid's position in its orbit and were used to triangulate the location of the fireball's main flare over the Central Kalahari Game Reserve.
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- This small rock found in the Saharan Desert may hold clues to our early planetary system and how the Earth was formed. A meteorite discovered in the Saharan desert was found to have broken off from a protoplanet from the early Solar System before Earth and the remaining planetary bodies had formed.
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- The meteorite was found in Adrar, Algeria, in May 2020, and was named “Erg Chech 002“. Most of the meteorites found on Earth are made up of basalt, a kind of rock that forms after lava rich in magnesium and iron cools off.
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- However, EC 002 contains an abundance of “andesite“. Andesite is found on Earth in areas where the planet’s tectonic plates have collided with one another, forming different layers on top of each other.
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- The meteorite was once molten, having solidified 4.565 billion years ago. Earth is believed to be 4.543 billion years old, meaning the rock predates our planet. The rock also has an interesting past: it is a small chunk off of an asteroid that originally came from a destroyed protoplanet.
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- Protoplanets are the primordial worlds that served as some of the largest objects that built the planets as we see them today. This meteorite is the oldest “magmatic rock” analyzed to date and sheds light on the formation of the primordial crusts that covered the oldest protoplanets.
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- The findings suggest that early protoplanets may have merged with other planetary bodies or have been completely destroyed before the formation of the planets that orbit the Sun since they differ in composition.
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- Meteorites are typically pieces of asteroids that have fallen off and floated through space before crashing into Earth. Meteors and other space rocks formed the building blocks of the solar system, including delivering organic compounds essential to life to Earth.
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- Scientists study meteorites because they are like jigsaw pieces, each telling us a little more about the larger story of how the Solar System formed and how life came to be on our planet.
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- Meteorites can be traced to particular “families” of asteroids based on their chemical composition. Andesite-rich meteorites are fairly rare, though a few have been found in recent years, including two discovered in 2009, and another in 2017.
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- The discovery of a meteorite provides scientists with a rare look at the Solar System shortly after it had formed. Around 4.5 billion years ago, a cloud of dust and gas formed the planetary bodies that make up the Solar System.
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- The andesite meteors could give crucial clues to what came before the planets were fully formed.
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- The age of iron meteorites implies that accretion of protoplanets began during the first millions of years of the solar system. Due to the heat generated by 26Al decay, many early protoplanets were fully differentiated with an igneous crust produced during the cooling of a magma ocean and the segregation at depth of a metallic core.
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- The formation and nature of the primordial crust generated during the early stages of melting is poorly understood, due in part to the scarcity of available samples. The newly discovered meteorite Erg Chech 002 (EC 002) originates from one such primitive igneous crust and has an andesite bulk composition. It derives from the partial melting of a noncarbonaceous chondritic reservoir, with no depletion in alkalis relative to the Sun’s photosphere and at a high degree of melting of around 25%.
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- EC 002 is, to date, the oldest known piece of an igneous crust with a 26Al-26Mg crystallization age of 4,565.0 million years. Partial melting took place at 1,220 °C up to several 100,000 years before, implying an accretion of the EC 002 parent body ca. 4,566 My ago.
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- Protoplanets covered by andesitic crusts were probably frequent. However, no asteroid shares the spectral features of EC 002, indicating that almost all of these bodies have disappeared, either because they went on to form the building blocks of larger bodies or planets or were simply destroyed. Interesting history in space rocks.
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- June 12, 2021 METEORITES - history in meteorites 3185
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