Original subtitles

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- [Narrator] Gaia launched in December 2013.

It's five-year mission, to study the billions of stars

in our Milky Way galaxy.

It's first data release covered a mere one billion stars

and the distance and motions for just two million.

Now its second data release has updated this

to an extraordinary 1.7 billion stars.

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The second data release of ESA's Gaia mission has produced

an extraordinary catalog

of over one and a half billion stars in our galaxy.

Based on observations between July 2014 and May 2016,

it includes the most accurate information yet

on the positions, brightness, distance, motion,

color and temperature of stars in the Milky Way

as well as information on asteroids and quasars.

- The data comes down to the ESA antennas

on the Estrack network

in Argentina, in Spain and in Australia.

From there it goes to Darmstadt who control the spacecraft

and then it goes to central data processing hub

near Madrid in Spain, which is an ESA center.

And from there, it goes to the data processing consortium

which then slices it up in different parts

and processes this into science products.

- [Narrator] This new image showing

the distribution of stars in the Milky Way

represents 22 months of observations.

1.7 billion stars, their distance, motions and color.

The dark areas are not empty.

They contain interstellar gas and dust.

- So Gaia is measuring with three different instruments.

It is doing astrometry, photometry and spectroscope.

So astrometry is measuring the positions

which helps to get the distances

and also the motion of the stars.

Photometry is essentially getting the color of the star

and color give us the temperature of the star.

- [Narrator] This stunning new image

was produced by recording the color from stars

and combining it with their overall brightness.

We now know the position

and brightness of 1.7 billion stars.

Importantly, as well as the color,

we also know the distance

and proper motion of 1.3 billion stars,

plus the surface temperature of 161 million,

the radius and luminosity of 77 million

and the radial velocity of 7 million stars.

- With spectroscopy we are using one element

which is based on Doppler effect.

We are looking how the lines on the spectro are moving

and we get the speed of the star on the line-of-sight.

But spectroscopy can also be used

to analyze better the stars.

So it is really the combination of all these elements.

We know where the stars are, how they are moving,

what is their temperature

and what are the properties of these stars.

The most eagerly awaited result from Gaia

are so-called parallaxes

which is the measurement which gives a handle

to the distance of the stars.

And this is a very tough measurement to be done

and we have known since Hipparcos, the previous ESA mission,

distances to about 100,000 stars

and Gaia is going to increase that number

to above one billion so that is a real revolution.

- [Narrator] The raw data from Gaia is used to create

stunning visuals and animations.

Obtaining the parallax measurement involved determining

the apparent motion of the star

by using two different vantage points

along the earth's orbit around the sun

and separating it from the star's

true motion through the galaxy.

To do this, the spacecraft is orbiting

around the L2 Lagrange point.

The sun, the earth and the moon

are all roughly in one direction

and the sum of gravitational forces

makes it an ideal position to study the stars

at the dark side of the sky.

Closer to home, Gaia observed

14,000 known solar system objects too, mainly asteroids.

The quality of data provides us pinpoint accuracy

over time of these orbiting neighbors.

- So we have a multitude of targets.

We have solar system objects, asteroids,

most of them are stars,

but we also see external galaxies and quasars

and it is really different kind of science

what you can get out from this.

From solar system targets,

we can measure their positions extremely accurately.

We will know much better, than ever before,

the orbits of asteroids, for example.

Stars we are using to understand our Milky Way better.

From stars we get really the structure of our galaxy.

And the advantage of seeing some quasars is that

the reference system of coordinates is based on quasars

because they are far away so they don't move

and we can observe them in radio and now,

finally, with Gaia we can see the same objects

in optical wavelengths so we can tie

radio reference system to optical.

- [Narrator] This animation of our own galaxy,

the Milky Way, shows the roughly 100 billion stars.

The location of the earth's sun is shown here

in one of the spiral arms.

The Hipparcos survey is in red;

it pinpointed the positions of

more than 100,000 stars to a high precision.

Gaia has surveyed up to 30,000 light years in all directions

encompassing one and half billion stars.

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Galaxies come in all shapes and sizes.

Only one of them is our home.

Gaia is opening up our part of the galaxy

to help us understand the past, present and future

of our region of space.

The first data release already produced

hundreds of scientific results

but for astronomers across the world,

the best is yet to come.

- The essential thing of the Gaia mission is

that the surprises will come later

because we make the catalog

and it is the scientists in the community

who are going to utilize it

and give the scientific surprises to us.

- [Narrator] The Gaia mission is expected

to be extended to 2020

which means not only cataloging more stars

but also examining possible exo planets around them

and even more surprises.

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A SpaceX Falcon 9 is readied for launch.

The Falcon 9 rocket has proven its ability and reliability

and become one of NASA's go-to launchers.

- [Announcer] Zero

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Lift off.

A SpaceX Falcon 9 carry test.

A planet led spacecraft that will search for new worlds

beyond our solar system.

- [Narrator] Its payload is TESS,

the transiting exoplanet survey satellite,

NASA's newest exoplanet mission led by MIT.

It will find thousands of new planets orbiting nearby stars.

- [Announcer] And visual confirmation as well

of the fairing separation.

- [Pilot] Grapes head deployed.

- [Narrator] TESS will eventually fly in a special,

highly elliptical orbit that maximizes the amount of sky

the spacecraft can image.

It will expand its orbit until it can get a

gravitational assist from the moon.

This slingshot will move it into a stable orbit

that is tipped at about 40 degrees

from the moon's orbital plane.

TESS will orbit the Earth in exactly half the time

it takes the moon to orbit once.

This feature helps stabilize the spacecraft

against tugs from the moon's gravity.

The telescope will then spend most of its

13.7 day orbit observing the sky.

As it nears Earth, it will rotate and transmit

all its accumulated data to scientists on the ground.

Over its two year mission,

TESS will observe nearly the entire sky

and potentially find thousands of new exoplanets.

- TESS, the transiting exoplanet survey satellite,

is NASA's newest exoplanet mission.

It's being led out of MIT and it's gonna find thousands

of new planets orbiting bright, nearby stars.

And it's going to build upon the legacy

of the Kepler mission;

only it's gonna focus on nearby bright stars

that are sprinkled across the whole sky

and its gonna help us answer really important question

and that is,

which of our nearest stellar neighbors has planets.

- [Narrator] In those two years,

TESS will look for signs of planets

ranging from Earth size to giants larger than Jupiter.

TESS will search for these new worlds, or exoplanets,

using transits, the same method as the Kepler mission.

As a planet passes in front of its star,

it blocks some of the light,

causing a slight drop in brightness.

TAS can detect these subtle dips and even use them

to determine some basic features of the planets

such as their size and orbit.

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- The coverage of the TESS cameras is unprecedented

in terms of the amount of sky that they can actually see

at any given time, and also their ability to cover

such a broad portion of the sky.

The types of targets that TESS will allow us to find

will enclose, essentially, all of the bright nearby stars.

- [Narrator] Each of TESS's cameras

has a 16.8 megapixle sensor covering a 24 degree square

large enough to contain an entire constellation.

TESS will watch each observation sector for about 27 days

before rotating to the next one,

covering first the south and then the north

to eventually build a map of 85% of the sky.

- The thing that we're really excited about with TESS

is the way that it will actually build on the momentum

that we started with Kepler.

So TESS is going to take that same search approach

but apply it to the vast majority of the sky

which still hasn't really been looked at in detail

when searching for exoplanets.

And by focusing, especially on planets that orbit

bright nearby stars, TESS allows us to start looking at

things like planet composition, atmospheric makeup,

and that'll then be crucial when we wanna start looking

around stars that are even further away

and in deeper parts of the galaxy as well.

- [Narrator] This coverage,

about 350 times what Kepler first observed,

will make TESS the first exoplanet mission

to survey almost the entire sky.

TESS is the vanguard of a new era of exoplanet study

and will forever expand our understanding

of worlds beyond our own.

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The space telescope Cheops,

characterizing exoplanet satellite,

is ESA's follow up mission.

The telescope will study hundreds of known exoplanets

using the transit method, measuring the dip in light

as a planet transits it's parent star.

- When the planet goes in front of the disk of the star

then the light that we receive from the star decreases.

And so, this is what we want to measure;

how much this light decreases when the planet

goes in front of the star.

And this is what's called the transit method.

- [Narrator] Hundreds of known planets

or orbiting stars outside our solar system

will soon be under scrutiny by Cheops.

- We want to know what these planets are made of,

we want to know how hot they are,

we want to know their atmospheric composition structure,

we want to know the surface temperature,

we want to know if there is water there

and eventually if there is life.

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- [Narrator] This is the Cheops instrument

in a clean room at the University of Bern

where it was built, assembled and tested

using electrical and optical ground support equipment

and a thermal vacuum chamber.

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Cheops will measure the minute dip in light from a star

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when a planet transits across it.

The size of the dip provides a direct measure

of the ratio of the size of the planet and the star.

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This, combined with the knowledge of the size of the star,

gives the planet's size.

Radial velocity measurements from ground observatories

will supply its mass.

- When you have the mass and the radius,

you have two very important

things about an object

because you can get, what we call,

the mean density after that.

And that can give you a lot of information

about the composition of a planet.

For example, it can immediately tell you whether

the planet is mainly formed of gas

or if it's a rocky planet.

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- [Narrator] The telescope houses two mirrors,

a CCD detector or camera and a baffle to reduce stray light.

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- What makes Cheops unique?

It's the only follow up mission.

So we are not aiming at discovering new planet,

we are just aiming at going back to the ones we know

and measure their size either for the first time

because it hasn't been measured yet,

or improve the measurement that have been done in the past

either from the ground or from a test space telescope

with less precision.

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- [Narrator] The challenge was to build an extremely

accurate and stable telescope that blocked signals

caused by stray light from its electronics and instruments.

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The telescope will, therefore,

be kept at -10 degrees Celsius

and the detector at -40 degrees to reduce signal noise.

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The Cheops science team is currently selecting

the best target exoplanets for further study.

Other scientists will also be invited to submit proposals

to use the space telescope.

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Now in Madrid for further launch preperations,

launched from ESA's facilities aboard a Soyuz rocket,

the Cheops will begin a new era of discovery.

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A recent analysis of six year's of data

from the MOA-II ground based survey

concludes that exoplanets similar to Neptune

in mass and probably composition

are likely the most common worlds

in the outer reaches of planetary systems.

This data was achieved by a technique called microlensing.

When a star passes directly between us

and a more distant star,

its gravity can act like a lens

magnifying the background star's brightness

significantly for a few weeks.

If the lensing star hosts a planet,

the planet's gravity can produce a noticeable change

in brightness for hours or days.

This spike signals not only the planet's presence,

but tells us its mass and distance from the star.

Each method of finding exoplanets has different strengths.

Radio velocity measurements reveal planets

by detecting how they cause the star to move.

Transit measurements reveal dips in star light

caused by planets passing in front of their stars.

Both work best for massive planets in close orbits

and for stars up to hundreds of light years away.

Microlensing opens a planetary window

onto a larger part of the galaxy

reaching thousands of light years.

And because microlensing is more sensitive

to smaller planets farther from their stars,

it can reveal new planetary populations.

In the MOA-II study, researchers discover

that planets beyond a certain distance from their star

tend to be roughly 20 earth masses,

or about the same as Neptune.

That distance is what astronomers call the snow line

where water would be frozen

during the formation of a planetary system.

For our system, that location is roughly 2.7 times

farther from the sun than Earth.

Beyond the snow line where there is more solid material

to coagulate and initiate the planet formation process,

planetary formation is thought to be most efficient.

In fact, worlds formed in this frozen hinterland

may plan an important role in making habitable planets

closer to their star.

The gravity of planets beyond the snow line

can help send water rich asteroids inward

where they can deliver water to young rocky worlds.

To validate this theory, you need a space based telescope

with some unique properties.

NASA's new telescope, WFIRST,

is the wide field infrared survey telescope.

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- Telescopes generally come into two different flavors.

You have a really powerful, big telescopes

but those telescopes see a tiny part of the sky

or telescopes are smaller, and so they lack that power,

but they can see big parts of the sky.

WFIRST is the best of both worlds.

- WFIRST is the wide field infrared survey telescope.

What I think of WFIRST as doing

is building on what were the two great successes

astronomically of the 1990s and the last decade,

that is, the Sloan Digital Sky Survey

and the Hubble space telescope.

- WFIRST is a NASA observatory

that has the top ranking of the National Academy of Sciences

to launch in the 2020s.

It has the same image precision and power

as the Hubble space telescope

but with 100 times the area of sky that views.

- Looking at a large fraction of the sky allows you

to get a more complete accounting, for example,

the stars in the Large Magellanic Cloud

which is the nearest galaxy to us

or the stars in the Galactic Bulge

so you can do a much more complete accounting

in a much shorter amount of time.

The particular thing I'm interested in using WFIRST for

is to actually do a statistical census

of planetary systems in our galaxy.

And what were looking for

is gravitational microlensing events.

These are cases when another star passes in front of

our line of sight to a background star

and it makes that background star get a little bit brighter

due to the gravity of that foreground star

and that allows us to find planets.

- What WFIRST will do is it'll have

what we call a coronagraph.

A coronagraph lets us image and characterize

really dim planets next to very bright stars.

- No matter how good a telescope that you build,

it's always gonna have some residual errors.

This is gonna be the first time

that we're gonna fly an instrument that contains

these high format deformable mirrors

that are gonna let us correct for errors in the telescope.

It's never been done in space before.

WFIRST will allow us to potentially make

ground-breaking discoveries;

finding out what dark energy is.

So this will tell us if dark energy is

a known form of energy

or if it's a modification of general relativity.

- Single WFIRST images will contain over a million galaxies.

And we can't categorize

and catalog those galaxies ourselves.

Citizen science allows interested people

in the general public to solve scientific problems,

and so, one of the things that I'm really excited about

is enabling this bridge where the general public

can get involved in doing actual science.

- For me, it's really exciting opportunity

to play a significant role in a mission

that I think will be one of the most powerful

telescopes that we have in the 2020s

and will be some of the most important things

our country does in space in that timeframe.

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- [Narrator] With these new eyes in the sky,

there seems no limit to our ability

to unlock the mysteries of our universe.

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