WEBVTT

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[MUSIC PLAYING]

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- It appears some pieces
of asteroid Vesta ended up

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on asteroid Bennu, according
to observations from

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NASA's OSIRIS-REx spacecraft.

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The new result sheds light on
the intricate orbital dance

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of asteroids and on the
violent origin of Bennu, which

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is a rubble pile asteroid that
coalesced from the fragments

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of a massive collision.

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

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were discovered scattered across
Bennu's southern hemisphere

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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 10 times brighter

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than their surroundings.

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The unusual boulders
on Bennu first

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caught the team's eye in images
from the OSIRIS-REx camera

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suite instrument.

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The team analyzed
the boulders using

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an onboard spectrometer,
which separates light

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into its component colors.

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Since elements and compounds
have distinct signature

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patterns of bright and dark
across a range of colors,

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they can be identified
using a spectrometer.

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The signature from
the boulders was

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characteristic of
the mineral pyroxene,

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from Vesta and the Vestoids.

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Smaller asteroids
that are fragments

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blasted from Vesta when a
sustained significant asteroid

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impacts.

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The team tested a few
different theories to determine

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the origin of these boulders.

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First, it's possible that the
boulders were originally part

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of Bennu or its parent body.

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However, this is unlikely based
on how pyroxene is created.

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This mineral typically
forms when rocky material

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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

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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

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in the main asteroid
belt. So the team

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ruled out these scenarios
and instead considered

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other pyroxene
rich asteroids that

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might have implanted
this material

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to Bennu or its parent.

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This is possible because
as asteroids move

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through the solar
system, their orbits

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can be altered in
many ways, including

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by the pull of gravity from
planets and other objects,

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meteorite impacts, even the
slight pressure from sunlight.

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The new result helps pin
down the complex journey

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Bennu and other
asteroids have traced

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through the solar system.

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