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Pre-existing mineralogy may survive lunar impacts

Large impacts on the Moon can form wide craters and turn surface rock liquid. Geophysicists once assumed that liquid rock would be homogenous when it cooled. Now researchers have found evidence that pre-existing mineralogy can survive impact melt.
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Lunar impacts created seas of molten rock

A new analysis of data from NASA's Lunar Orbiter Laser Altimeter (LOLA) shows that molten rock may have been present on the Moon more recently and for longer periods than previously thought. Differentiation - a settling out of rock layers as liquid rock cools - would require thousands of years and a fluid rock sea at least six miles deep.
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NASA Scientists Find History of Asteroid Impacts in Earth Rocks

Research by NASA and international scientists concludes giant asteroids, similar or larger than the one believed to have killed the dinosaurs, hit Earth billions of years ago with more frequency than previously thought.
To cause the dinosaur extinction, the killer asteroid that impacted Earth 65 million years ago would have been almost 10 kilometres in diameter. By studying ancient rocks in Australia and using computer models, researchers estimate that approximately 70 asteroids the same size or larger impacted Earth 1.8 to 3.8 billion years ago. During the same period, approximately four similarly-sized objects hit the moon.

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 Ancient asteroids kept on coming

A wave of asteroids showered Earth and the Moon in the distant past. They scarred the lunar surface with vast, circular impact basins and wreaked even greater havoc on this planet, which presented a bigger target. Now, a pair of studies published in Nature suggests that the battering lasted much longer than was thought, spanning nearly the entire first half of Earth's history. The results imply that a prolonged succession of impacts - some of them large enough to vaporise oceans - could have shaped the early evolution of life.
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Asteroids Smacked Moon Stronger & Faster 4 Billion Years Ago

The moon, which has been pummelled by a barrage of asteroids and debris throughout its lifetime, experienced a strong up surge in the energy and speed of incoming rocks around 4 billion years ago, new research suggests.
A team of researchers from the NASA Lunar Science Institute (NLSI) at the Ames Research Centre in Moffett Field, Calif., tracked the history of crater formation on the moon using digital maps, and found evidence of a dramatic shift in the velocity and energy of the asteroid bombardment during a period called the "lunar cataclysm" that occurred 4 billion years ago.

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Meteorites delivered gold to Earth

Scientists have shown that the Earth's surface became enriched with precious metals by impacting meteorites.
The Earth's crust and mantle has considerably more gold than expected from favoured models of planetary formation.
A study from the University of Bristol looked at some of the oldest rocks on Earth, demonstrating that gold was delivered by meteorites long after their formation.
Their results are published in Nature.

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Meteorite storm showered planet in gold

Four billion years ago, the newly formed Earth took a walloping. A storm of meteorites slammed into it, delivering gold and other new metals to the planet.
Earth's crust and mantle should not contain metals like gold, because while the planet was molten they would have sunk into the core. As a result, many geologists think they were supplied by one final meteor bombardment after the planet solidified.

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New research has claimed that bombardments of 'micro-meteorites' on Earth and Mars four billion years ago may have caused the planets' climates to cool dramatically, hampering their ability to support life. Scientists from Imperial College London studied the effects of the Late Heavy Bombardment ( LHB), a period of time in the early Solar System when meteorite showers lasting around 100 million years barraged Earth and Mars.
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The end of planet formation, as told by trace elements from the mantles of Earth, the Moon and Mars

New research reveals that the abundance of so-called highly siderophile , or metal-loving, elements like gold and platinum found in the mantles of Earth, the Moon and Mars were delivered by massive impactors during the final phase of planet formation over 4.5 billion years ago. The predicted sizes of the projectiles, which hit within tens of millions of years of the giant impact that produced our Moon, are consistent with current planet formation models as well as physical evidence such as the size distributions of asteroids and ancient Martian impact scars. They predict that the largest of the late impactors on Earth, at 1,500-2,000 miles in diameter, potentially modified Earth's obliquity by approximately 10 degrees, while those for the Moon, at approximately 150-200 miles, may have delivered water to its mantle.
The team that conducted this study comprises solar system dynamicists, such as Dr. William Bottke and Dr. David Nesvorny from Southwest Research Institute, and geophysical-geochemical modellers, such as Prof. Richard J. Walker from the University of Maryland, Prof. James Day from the University of Maryland and Scripps Institution of Oceanography and Prof. Linda Elkins-Tanton from the Massachusetts Institute of Technology. Together, they represent three teams within the NASA Lunar Science Institute (NLSI).

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NASA's LRO Exposes Moon's Complex, Turbulent Youth

The moon's surface is more complex than previously thought and was bombarded by two distinct populations of asteroids or comets in its youth, according to three new papers in the Sept. 17 issue of Science that describe data from NASA's Lunar Reconnaissance Orbiter.
Two of the papers describe data from LRO's Diviner Lunar Radiometer Experiment instrument that reveal the complex geologic processes that forged the lunar surface. The data showed previously unseen compositional differences in the crustal highlands, and confirmed the presence of anomalously silica-rich material in five distinct regions.

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