WEBVTT

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From the beginnings of our solar system
four and a half billion years ago,

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there
remain tantalizing clues to its evolution.

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Remnant debris, asteroids and comets,
they vary in size

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from grains of dust to mountainsides,
from footballs to planetoid.

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They were the building blocks

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of the planets and perhaps carry
the origins of life itself.

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No, within our grasp,
these rocks of ice and dust

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are ready to give up their secrets.

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Asteroids are believed to be made
of contrails, flash, heated

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grains of rock within the stellar disk
of our forming solar system.

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These contrails cluster together, forming
the first asteroids

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and the building blocks of the planets.

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Once the solar system had evolved,
there was a lot of asteroid

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material left over.

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They cover a broad spectrum of types.

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The largest of these are minor planets
or planetoid,

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large enough to have an ovoid shape.

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This category took the previous planet
Pluto off the major list

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and onto the minor.

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The smallest remnants of debris
are often called meteoroids.

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There are, in fact, several minor planets.

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Some have been seconded
into planetary orbit and become moons.

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The traditional asteroid belt between Mars
and Jupiter has one called

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Ceres, the largest
and the first to be detected

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with our first

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close up of an asteroid
was courtesy of Galileo.

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On its flight through the main
asteroid belt towards Jupiter,

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it photographed 951 gas from an S-TYPE

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asteroid with an average diameter
of just over six kilometers.

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The S stands for a stony composition.

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Galileo then photographed a larger
two for three Ida at 15

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and a half kilometers wide, revealing
that it has its own moon named Dactyl.

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Asteroids are not limited to the asteroid
belt between the orbits of Mars

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and Jupiter.

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Many orbit much closer to Earth
and are known as near

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Earth objects or Neos.

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Radar is a very powerful instrument
that we use to study near-Earth asteroids.

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Asteroid two taught us
was millions of kilometers away

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and we were able to resolve surface rocks.

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We could see boulders.

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There are currently only
two radar facilities

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in the world
that have sufficient sensitivity

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for doing regular observations
of near-Earth objects.

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Arecibo and Goldstone.

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Even the most powerful optical telescopes,
and I'm talking

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even Hubble telescope, they can only see
this asteroid as a point of light.

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It is just too far in too small.

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It provides an extraordinary opportunity
to get very detailed radar images.

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You are transmitting microwaves,
propagating

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at the speed of light
to where the asteroid it is bouncing back.

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This radar

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echoes containing surface
features of the asteroid.

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It's telling us about its rotation
and its very precisely

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pinpointing its distance from the radar.

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These asteroids were imaged with ground
based radar.

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VLA 86 revealed it has its own moon
and asteroid HQ 1 to 4 passed

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very close to earth, some three and
a quarter times the distance to the moon.

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It is due to return sometime in the 24th
century.

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Scientists are looking much more closely
at these objects for their potential

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to pass through Earth's orbital plane
and perhaps

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pose a threat.

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The most common

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type of asteroid
is the c-type carbonaceous.

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Accounting for about 75% of known

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asteroids.

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The probe near Shoemaker
was the first dedicated asteroid probe

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launched by NASA.

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It photographed 253 material.

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The C-Type then moved on to 433.

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Eros, the largest, visited at the time
where it orbited.

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Took extensive measurements
and more by accident than good planning.

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Landed on the asteroid.

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The first probe to do so.

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Deep Space One, an

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experimental Nassar probe,
was sent to investigate an asteroid 1969.

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Braille technical errors returned
poor imagery.

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However, the probe continued on
to its second rendezvous

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for the first time with a comet 19 B
barrel.

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Comets are closely related to asteroids,

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but originate from the cold, dark,
outer boundaries of our solar system.

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Comets are bodies in our solar system
that have been left over

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ever since the solar system
formed some 4.5 billion years ago.

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And therefore, when we look into comets,
we look into the past of our solar system.

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And so by investigating the details
of comets, how they formed, how

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they evolved, we can actually have
a glimpse into how our solar system formed

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and in the end, how the earth formed
and why we are.

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Comets have been recorded
throughout history

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as they are easily observed
when close to the sun.

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Often considered an omen.

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One comet of note was Halley's

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Comet.

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In 1986,
Halley's Comet returned once again,

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and this time it was met
with a veritable armada of space

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probes.

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The first attempt at a space

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rendezvous was with
the International Comet Explorer, or Icy.

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It passed through the tail of Comet A21
b Jekyll benison

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on its way to meet Halley.

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The European Space Agency sent Giotto.

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The Russian and French sent two probes
via Venus, Vigo, one and Vega to Japan.

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Since we see and second copy that
country's first deep space probes.

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Their measurements
went on to refine the targeting for Johto

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to make a much closer pass of the comet's
nucleus than first planned.

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In 1994, astronomers and scientists
were given an unexpected treat.

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Comet Shoemaker-Levy broke apart

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and struck Jupiter in a spectacular,
live, violent fashion.

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Comets required more study.

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The Stardust probe was dispatched

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to investigate five,
five, three, five and Frank Wild two.

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And then the Tempel one comet.

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It returned a sample of cometary tail
to earth.

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Our biggest discovery that we did

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was looking at this cometary material
that was returned from NASA's

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Stardust mission and the Stardust mission
when a rendezvous with a comet

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brought back

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very small amounts of material,
comet material and comet exposed material.

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We had basically one shot at
looking at this, and it was really pushing

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the limits of detection.

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So I spent about two years
optimizing our technique,

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really rehearsing, practicing,
getting everything as

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as perfect as possible
before the one day of doing measurements

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and sort of all leading up to one big one
big game, one big day.

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And also just working with meteorites
and working with the cometary material

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and working with something
that's four and a half

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billion years old, that very few people
ever get to play with.

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And to the few days of being able
to do the actual measurements

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make up for all of the rehearsals
that it takes.

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JAXA launched Hayabusa
to study Asteroid 25143 Itokawa

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and to retrieve a sample from the surface
in a touch and go maneuver.

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The mission took a total of seven years
to accomplish

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with the sample return pond retrieved
from the Australian outback in 2010

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to go

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launched a
year earlier by the European Space Agency.

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It was a very ambitious spacecraft
called Rosetta.

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Its goal to land a probe on a comet

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67 or tourism of Geodesy Mango.

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Just getting there was to prove
a challenge in astro navigation.

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But when you want to

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rendezvous with a comet,
you have to accelerate the spacecraft

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and match the same velocity
that the comet has around the sun.

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So this is the problem, not only
the distance, but also the velocity.

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There is no rocket that can give us
the velocity needed to be

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as fast as the comet I close to a planet.

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And you use the gravitational attraction
of the planet to actually accelerate

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your spacecraft.

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It's passed

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by asteroids, two eight,
six, seven Steins and 21 Lutetia.

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Due to is

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a very strange target,
a very strange asteroid.

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We believe that

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it may be a C class asteroid,
which means that it is very primitive.

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However, it shows from ground
based and also Spaceborne observations

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that Eluted said that does not
look completely like a C-Type asteroid.

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And we are really puzzled
about what it really may be.

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The spacecraft then moved on
to its primary target, Comet 67 P.

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The nucleus is pulling the spacecraft

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out of its planned orbit

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and that can be seen as a shift

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in frequency of the transmitted radio
signal from the spacecraft.

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And the extent of this frequency shift

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is a measure
of the mass of the comet nucleus.

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So we are able to view the nucleus here.

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There is no ice at the top.

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So it's covered by a mantle
that we consider is essentially made

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of organic material.
That's why it's very dark.

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And this material is one of the key thing
we would like to explore and analyze.

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These organics may hold

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the secrets to life on Earth.

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What it's all about
is the carbon chemistry.

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How much did the comets bring to Earth?

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So was it just the right elements?

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The right yeah. The right building blocks?

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Or was there more information in it
when these comets already arrived?

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To try and answer these questions.

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ESA attempted one of the most daring
missions mankind has ever undertaken

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to land a probe
on the surface of the comet.

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Landing on a comet
is one of the hardest things

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that has ever been done
by the human species.

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This is the comet.

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It's roughly a one in a thousand model.

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So the real thing is thousand
times bigger.

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The landing site is roughly here, which
we are aiming for to deliver the lander.

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It's the flattest part we could find.

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What we are studying at the moment
with the instruments are basically

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what are the ingredients,
which materials are present

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and coming back to do
one of the objectives of the mission.

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How complex are the materials
present at the comet?

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Lending means

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flying very, very

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slowly over the comet
and then gently pushing away.

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The lander is not a landing
like you can imagine on the moon

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where you come with rockets
and you have to break here.

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The problem is the opposite.

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You have to really touch gently.

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The comet.
The forces involved are very small.

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If I get meaningful details,
that would be just marvelous. If.

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If the descent works, the landing is okay.

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We receive a sample and the whole thing
runs smoothly.

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That would be just great.

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But it is a lot of luck, really.

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We had a lot of luck already.

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Now. So we are sitting on the surface.

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A few days talking to us.

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More data to come and to do a nice thing
down, which you should do.

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Of course we are there. It's done its job.

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We are on the comet.

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The science has started.

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Now we have the first results that give us
the first comprehension of what

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we think the comet is,
where it started from.

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Now, for the rest of the year,
we will watch how the comet evolves.

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Will unlock how the comet works.

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We're looking at where the gas and the
dust start to accelerate from the surface

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and how that beginning of the comet,
that birth of the coma works.

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So how the coma develops
as it does to higher altitudes,

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this region has only ever been
theoretically constrained or modeled.

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These will be the first measurements
we make in this area or this region.

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And that's that's
a really big important target for us.

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Eventually, the tiny probe shut down.

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Having feeling reactivated
is not so likely, but is not impossible.

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Philae was designed to hibernate,

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was designed to to switch off
and be able to reactivate itself.

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Of course, we expected this

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to be a duration of a few days
or a few weeks, not a few months,

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but okay, we will see.

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Maybe we are lucky
and the UNICEF survive this

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this months
and will reactivate in June-July.

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While observing
the asteroid, scientists were surprised

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to find one
with what looked like a cometary tail.

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After careful study, scientists realized

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they were observing the results
of the impact of two asteroids.

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596. Shayla had been struck at high speed
by a small asteroid.

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The impact with the force of
a 100 kiloton nuclear bomb.

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Nassar had

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done something similar with Deep Impact,
a probe sent to comet Tempel one,

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where it dispatched a kinetic impactor
which struck the comet.

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To study the impact
and the debris thrown up as a consequence

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and soon after, Nassar launched
another small ion

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powered probe, Don,
which also had an extraordinary mission

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to travel deep into the asteroid
belt between Mars

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and Jupiter.

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Its targets,

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two of the largest asteroids
in the solar system.

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Dawn rendezvoused with four Vesta
and orbited it for over a year,

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returning a wealth of data.

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Dawn then departed

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and cruised toward
Ceres, the largest of the asteroids.

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A planetoid,
but it has obtained orbit and begun

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its study.

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JAXA, the Japanese space agency,
has recently launched a second Hayabusa

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probe, this one
with many improvements over the first.

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Its target is the C-Type asteroid

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1990 9gu3.

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It's expected to reach its destination
in three years,

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collect samples
and return to Earth by 2023.

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NASA has announced the Osiris-Rex
sample return mission to asteroid 1999.

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Q 36 better known as Bennu.

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It's expected
to launch sometime in the near future.

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And after a two year journey, orbit
and map the surface

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before touching down to retrieve
two kilograms of material.

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The probe samples
return is expected in 2023.

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There is also a practical reason

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to study asteroids.

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In 2013,

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an asteroid with a mass of about 9100
tons exploded over

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Chelyabinsk, Russia,
with the force of 20 Hiroshima bombs,

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causing 1500 injuries and damaging

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7000 buildings.

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It isn't the first asteroid strike
on earth, as the dinosaurs can attest to,

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and probably not the last.

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Through the United Nations,

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ESA and other major space agencies
have established a safeguard program.

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The Neowise data have returned two
very important findings.

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First, we've been able to determine
that we found 93% of all the

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near-Earth asteroids that are out there
that are larger than one kilometer.

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We've also been able to tell
that there are somewhat fewer near-Earth

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asteroids that are larger than 100 meters
and were previously thought.

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However, fewer does not mean none.

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That leaves about 15,000 asteroids larger

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than 100 years that remain to be found.

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This advisory group is also planning

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intervention missions if needed.

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We think that we can cope

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with deflecting an asteroid
with two different technologies.

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Mainly one is what we call

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kinetic impactor hitting the asteroid
and pushing it out of the way.

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The second one is take a heavy spacecraft
and use it as, say, a gravity tractor.

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So by the mass of the spacecraft,
you pull the asteroid away.

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There is

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one project in the planning stage
to snag a small asteroid in the near

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earth region
and drag it into a lunar orbit.

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There it can be met by astronauts
aboard an Orion capsule who will study

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the asteroid
firsthand, take extensive samples

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and return to Earth.

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For the more we know, the better prepared
we are to protect our place

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in the solar system.