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[music throughout] It appears some pieces of asteroid Vesta

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ended up on asteroid Bennu, according to observations from NASA’s OSIRIS-REx spacecraft.

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The new result sheds light on the intricate orbital dance of asteroids

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and on the violent origin of Bennu,

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which is a “rubble pile” asteroid that coalesced from the fragments of a massive collision.

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Six boulders, ranging in size from 5 to 14 feet,

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were discovered scattered across Bennu’s southern hemisphere near the equator.

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These boulders are much brighter than the rest of Bennu,

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with some appearing as much as 10x brighter than their surroundings.

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The unusual boulders on Bennu first caught the team’s eye in images

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from the OSIRIS-REx Camera Suite instrument.

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The team analyzed the boulders using an onboard spectrometer,

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which separates light into its component colors.

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Since elements and compounds have distinct, signature patterns of bright and dark

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across a range of colors, they can be identified using a spectrometer.

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The signature from the boulders was characteristic of the mineral

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pyroxene from Vesta and the vestoids,

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smaller asteroids that are fragments blasted from Vesta

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when it sustained significant asteroid impacts.

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The team tested a few different theories to determine the origin of these boulders:

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First, it’s possible that the boulders were originally part of Bennu

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or its parent body; however, this is unlikely based on how pyroxene is created.

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This mineral typically forms when rocky material melts at high-temperature.

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Bennu is composed of water-bearing minerals,

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so it wouldn’t have experienced very high temperatures in its history.

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Next, the team considered localized heating,

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perhaps from an impact.

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The scale of an impact needed to create large pyroxene boulders

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is much more significant than what is expected to take place in the main asteroid belt.

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So, the team ruled out these scenarios,

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and instead considered other pyroxene-rich asteroids

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that might have implanted this material to Bennu or its parent.

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This is possible because as asteroids move through the solar system,

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their orbits can be altered in many ways

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including by the pull of gravity from planets and other objects,

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meteoroid impacts, and even the slight pressure from sunlight.

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The new result helps pin down the complex journey Bennu

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and other asteroids have traced through the solar system.