WEBVTT FILE

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[Music]

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OSIRIS-REx is a NASA
mission to explore near-Earth

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asteroid Bennu, a remnant from
the dawn of the solar system,

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and to return a
sample of Bennu to Earth.

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On September 8, 2016, OSIRIS-REx
began its journey to Bennu from

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Cape Canaveral, Florida
aboard an Atlas V rocket.

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It lifted off shortly before
sunset, climbing eastward over

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the Atlantic Ocean to traverse
the night side of Earth.

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One hour later, OSIRIS-REx
separated from its Centaur upper

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stage rocket and
drifted into space.

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It deployed its solar arrays to
catch the rising sun, and made a

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final pass over Australia before
embarking on its outbound cruise

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to Bennu.

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After a year in orbit around the
sun, OSIRIS-REx briefly returned

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to Earth in September
2017 for a gravity assist.

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The spacecraft passed within
18.000 kilometers of Antarctica.

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then turned its instrument deck
toward home to capture images

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and spectra of
Earth and the Moon.

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The gravity assist bent the
trajectory of OSIRIS-REx by six

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degrees, matching the orbital
tilt of Bennu, and sending the

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spacecraft on a path
to catch its target.

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In August 2018, OSIRIS-REx
began its Approach phase.

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Its long-range camera captured
the first visible-light images

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of Bennu as a single pixel
moving across a field of stars.

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Over the following months, Bennu
grew from a pixel into a world,

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with OSIRIS-REx revealing its
shape, rotation, and color for

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the first time.

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Now, after chasing its target
for over two years, OSIRIS-REx

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is arriving at asteroid Bennu.

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On December 3 it will fire
its thrusters to match Bennu's

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velocity and begin
its Preliminary Survey.

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OSIRIS-REx will pass high
above the equator and the poles,

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measuring Bennu's position and
mass, and refining its size,

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shape, and spin.

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On New Year's Eve, OSIRIS-REx
will venture close enough to

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Bennu to be captured into orbit
by its miniscule gravity, making

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it the smallest world ever to
be orbited by a spacecraft.

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In early 2019, OSIRIS-REx
will break orbit to conduct a

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Detailed Survey of Bennu.

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First, it will carry out a
mapping campaign called the

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Baseball Diamond.

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By observing Bennu at different
latitudes and times of day,

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OSIRIS-REx will capture stereo
images and identify large rocks

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on the surface that could pose
a hazard later in the mission.

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In its second mapping campaign,
OSIRIS-REx will observe Bennu

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from seven different
stations around its equator.

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At each station, it will take
measurements from pole-to-pole

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using its mapping camera,
laser altimeter, and two

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spectrometers.

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The combined data will provide
a detailed look at Bennu's

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geologic features
and its composition.

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This will improve landmark-based
navigation, and enable mission

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planners to begin looking for
places to collect a sample.

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Following the Detailed Survey,
OSIRIS-REx will once again enter

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orbit.

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At a radius of only one
kilometer, Orbital B will serve

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as the mission's safe home
orbit until sample collection.

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During this phase, OSIRIS-REx
will globally map Bennu.

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It will fly in a polar orbit as
the asteroid rotates beneath,

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enabling full
coverage of the surface.

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Orbital B's precession, or
wobble, will also be used to

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measure Bennu's gravity field,
along with the non-gravitational

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forces that are slowly
altering Bennu's trajectory.

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In mid-2019, OSIRIS-REx will
begin its Reconnaissance phase.

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It will break orbit and fly over
four candidate sample sites at

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225 meters. taking
high-resolution images.

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Flying at such close proximity
will reveal large pebbles that

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could pose a hazard
during sample collection.

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Mission planners will use this
information to select the two

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best sites for
additional inspection.

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At a range of 525 meters,
OSIRIS-REx will fly over the two

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final candidate sites,
spectrally mapping the surface

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to reveal its
chemical composition.

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This information will help
mission planners determine the

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most valuable site for
collecting the sample.

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Once the final site has been
selected, OSIRIS-REx will begin

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its rehearsal phase.

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Frist, it will practice
autonomous flight to a

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predetermined Check Point, where
it will start its descent during

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sample collection.

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Next, OSIRIS-REx will practice
flying to the Match Point.

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The spacecraft will lower to
within 30 meters of the surface

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to match Bennu's speed and
rotation, a necessity for safely

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touching the asteroid.

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Finally, in mid-2020, OSIRIS-REx
will be ready to collect a

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sample of Bennu.

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Before it descends to the
surface, the spacecraft will

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deploy its Touch-And-Go
Sample Acquisition-Mechanism, or

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TAGSAM, a new technology
invented for the mission.

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When it reaches the Check Point,
OSIRIS-REx will begin its final

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descent.

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It will pull back is solar
arrays for safety, and approach

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the surface at centimeters per
second, the walking pace of an

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insect.

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As the TAGSAM touches down, it
will blow high-pressure nitrogen

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gas into the soil,
stirring up loose material.

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A filter within the sample head
will trap rocks and dirt, while

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allowing the gas
to escape to space.

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Once the sample is collected,
OSIRIS-REx will fire its

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thrusters and back away from
Bennu, retreating to a safe

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distance with its
precious cargo.

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Following collection, OSIRIS-REx
will verify the status of the

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sample, using a
camera called SamCam.

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This visual inspection will
reveal whether any large debris

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is still attached to the sample
head, which could pose a hazard

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during stowage.

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Next, OSIRIS-REx will
verify the mass of the sample.

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It will fully extend its TAGSAM
arm and perform a spin maneuver,

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measuring the change in inertia
to determine the sample's mass.

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If at least 60 grams have been
collected, and the sample head

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is clear of hazardous debris,
mission planners will command

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the spacecraft to
stow the sample.

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StowCam will watch closely
as the sample head enters the

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return capsule and
is secured in place.

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OSIRIS-REx will then detach the
TAGSAM arm from the head, seal

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the sample return capsule, and
prepare for its journey back to

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Earth.

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After departing from Bennu in
early 2021, OSIRIS-REx will

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return to Earth in late 2023.

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Four hours prior to arrival,
the spacecraft will release the

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sample return capsule, then
deflect away from Earth to its

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final orbit, as its
piece of Bennu comes home.

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The capsule will enter the
atmosphere over the night side

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of Earth, streaking towards the
central California coastline at

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over 12 kilometers per second.

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West of the Great Salt Lake, at
an altitude of approximately 33

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kilometers, the capsule will
initiate its parachute sequence,

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stabilizing and
slowing its descent.

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Upon landing in the Utah desert,
the sample will be recovered,

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carefully removed from the
capsule, and taken to the

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OSIRIS-REx curation facility at
NASA's Johnson Space Center in

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Houston, Texas.

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This pristine material from
the early solar system will be

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studied for decades to come,
providing clues to the formation

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of the planets, to the evolution
of Earth, and to the ingredients

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that were present at
the origins of life.

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[Music]

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[Satellite  beeping]