Original subtitles

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- [Narrator] The interface between Earth and space

is the ionosphere, a region of rarefied gas

and charged particles.

It is very important for radio communications,

radar, satellite signals, and global positioning.

Yet, we know so little about it,

especially when it disrupts all these signals

in a regular fashion.

Too high for planes or balloons,

it's up to satellites to study this rarefied region.

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(exploding)

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We have become so reliant on radio signals

bouncing off the upper atmosphere,

and beaming down from satellites,

that the ionosphere has become a critical part

of our technology.

From aircraft communications and radar

to managing navigation of the world's shipping lanes

and global position for fishing trawlers

to locate their catch.

GPS for the military, on the ground and in the air.

Yet we know very little about this region

of the Earth's atmosphere.

Critically, there are times when global positioning

signals become unreliable.

The satellite and radio signals twinkle

in much the same way as bright stars appear

to do at optical wavelengths.

Irregularities in the ionosphere,

referred to as ionospheric depletions or bubbles,

span the hemispheres at the equator.

And they're a major element of the low latitude

geospace region.

- It's very important for us to understand

the ionized portion of the atmosphere,

the ionosphere, as well as the upper atmosphere,

because that's where satellites,

low Earth-orbiting satellites are orbiting,

in that region.

Astronauts are exploring that region.

As well as the communication and navigation signals

travel through that region.

And so when you have disruptions

in the ionosphere and variability in the ionosphere,

that can affect our navigation and communication systems.

- [Narrator] The ionosphere lies some 40 to 600 miles

above Earth's surface.

The upper atmosphere and ionosphere change constantly,

in response to forces from above and below,

including explosions on the Sun,

intense upper atmosphere winds,

and dynamic electric field changes.

These irregularities form huge horseshoe arcs

between atmospheres, with their apices centered

on the magnetic equator.

To learn more, NASA conducted a mission called CINDI,

the Coupled Ion Neutral Dynamics Investigation.

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CINDI was designed to measure ionization

of the upper atmosphere, including the behavior

of the irregularities responsible

for the GPS twinkling,

which turned out to be quite surprising.

The ionosphere becomes unstable shortly after the Sun sets.

As darkness falls, ionized atoms of molecules

begin to recombine into a neutral state.

During this transition period after sunset,

irregularities are quite strong.

As the night wears on, however, these irregularities

were thought to fade, and eventually vanish,

around midnight.

CINDI found many irregularities around sunset,

but they did not vanish around midnight.

On the contrary, there was another peak in irregularities

during the middle of the night.

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The second peak has appeared most pronounced

from June through August.

Scientists aren't sure yet why this second peak occurs

or why it varies by season.

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The CINDI mission ended with the reentry

of the spacecraft into Earth's atmosphere.

Researchers still had much to learn about the ionosphere,

and how it can affect GPS and other satellite systems.

To understand the tug of war between Earth's atmosphere

and the space environment, NASA created the ICON satellite.

(slow music)

- So if the ICON mission were looking at

the very upper levels of the Earth's atmosphere,

and the charged plasma environment

that surrounds the Earth, that we usually consider

the inner edge of space, so that region

is called the ionosphere, and that's what gave us the name,

for the Ionospheric Connection Explorer.

But really a lot of what is happening there

is being driven by the winds and the composition

of the Earth's atmosphere.

- So these altitudes, thermospheric altitudes that

the ICON mission is investigating, are typically

too low for satellites to fly in,

and too high for weather balloons to get to,

for example.

So we need to use remote sensing techniques

to get the information at the right altitudes.

And, the atmosphere actually helps us do it,

cause there is something called an air glow,

the atmosphere naturally just glows at those altitudes,

more during the day, less during the night,

but it's always there, this air glow is always there.

And by just looking at the color of this air glow,

we can find out about the wind and the temperature,

actually, so the atmosphere, in a way,

is helping us to understand how it is behaving,

by sending out this air glow.

And if we build the right instruments,

look at particular aspects of the color of the air glow,

we can get the information that we want.

- So what ICON is trying to do is observe

these two systems at the same time.

From one satellite, so it does that with four instruments,

and broadly speaking, three of those are kind of camera

instruments that look out at the Earth from the horizon.

One of them measures the temperature and wind

of that atmosphere.

One of them measures the composition of the atmosphere.

One of them is getting the plasma environment,

this charged particle environment,

and then the fourth instrument that measures

the charged particles and their motion and things

at the location of the spacecraft.

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- [Narrator] High altitude wind shear

is thought to be one of the factors for GPS twinkle.

- It's just the movement of the atmosphere,

same thing as we experience as wind down here,

except for the winds are generally much faster up there.

And there's very little atmosphere

so the pressure is very, very low.

So those are the two major differences

between what we think of when we say the word wind here,

and what we experience up there,

or what the instrument sees up there.

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- [Narrator] ICON was placed aboard a Pegasus rocket

and flown into the stratosphere

under the belly of an Orbital ATK aircraft.

Once it is at the right altitude and heading,

the rocket drops away, then ignites its main engine,

carrying the spacecraft into orbit.

(rocket propelling)

Once in orbit, the spacecraft is commanded by scientists

at the mission operation center

at the Space Sciences Laboratory at UC Berkeley.

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ICON then began its study of the frontier of space.

The dynamic zone where terrestrial weather from below

meets space weather from above.

In this region, the tenuous gases are anything but quiet,

as a mix of neutral and charged particles travels

through giant winds.

These winds can change on a wide variety of time scales,

due to Earth's seasons, the day's heating and cooling,

and incoming bursts of radiation from the Sun.

To understand what drives the variability

in the ionosphere is very complicated.

A system that is driven by both terrestrial

and space weather.

A second satellite mission was needed,

another suite of instruments in a higher orbit, named GOLD.

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A first for NASA, GOLD was piggybacked

on a commercial satellite.

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- The GOLD mission stands for Global Observations

of Limb and Disk, and it's a very important mission

for us to understand the upper atmosphere

of the Earth, the thermosphere and ionosphere of the Earth.

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It is our first hosted science payload

that NASA's flying on a commercial spacecraft.

And so that, is a new, innovative way for us

to do science.

That maximizes our private sector partnership as well.

- GOLD will be sitting 22,000 miles above Earth,

which means that it can see a whole half of the Earth,

all of the western hemisphere.

And it will be hovering over one particular point

on Earth, watching the dynamics of the atmosphere

play out below.

- [Narrator] From geosynchronous orbit,

GOLD can scan half the planet at a time.

- [Sarah] I'm excited about this mission

because GOLD will be getting information

about the upper atmosphere much faster than ever before,

and we'll be able to look at effects that are more like

the weather that we experience down here on Earth.

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- [Narrator] The two influences on the ionosphere

are space weather and weather below,

closer to the ground.

Space weather is the realm of the Sun.

Coronal mass ejections affecting our magnetic field,

and charring us with energetic particles.

The Sun's energy starts in its core,

a giant fusion engine, where hydrogen atoms

are turned into helium atoms.

The energy produced there moves up

through the convection zone to the Sun's surface,

the photosphere.

Moving magnetic field contribute extra energy along the way,

bursting from the surface, emitting light and heat,

that is channeled by the Sun's magnetic field,

generating the turbulent surface, including prominences,

flares, and coronal mass ejections,

that spread out into the solar system.

- Space weather is the field that studies

how what's going on on the Sun,

affects us here on the Earth, in our near-space environment,

and on the space environment on other planets.

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- [Narrator] These powerful bursts of energy

travel outward towards the planets.

This space weather, consisting of light

and thermal radiation, includes high speed solar wind

and energetic particles, which collide into planets

orbiting the Sun.

(burning)

Earth has some defense; its magnetic field deflects

and absorbs much of the energy,

distorting the magnetic field.

Some energy is captured and follows

the magnetic lines to the poles, generating auroras.

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(twinkling)

- NASA hopes to achieve with the GOLD and ICON missions,

a better understanding of the near-Earth space,

that's so important for our global infrastucture.

(exploding)

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- [Narrator] To help predict space weather,

many sentinel satellites watch the Sun closely.

IRIS is one of them.

It watches our star in ultra-violet wavelengths,

and is able to give us warnings of extreme space weather

events approaching Earth.

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This space weather has a direct influence

on our ionosphere.

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Another tool to watch both the solar weather

and the Earth's weather together

is about to go into operation,

replacing its aging predecessor.

GOES-R is a next generation weather satellite,

with the latest in technology.

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It will be five times faster,

advanced resolution cameras giving greater coverage

for hurricane tracking, real time mapping of lightning,

and improved solar flare monitoring.

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Almost by accident, the thermal x-ray telescope

in Earth's orbit discovered another source

of gamma ray particles coming from Earth.

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Under just the right conditions,

lightning storms fire off some of the highest energy

light naturally found on Earth.

Terrestrial gamma ray flashes, or TGFs.

Rising and falling snow and ice particles

repeatedly collide, filling the cloud

with electrical charge.

Once the electric field is strong enough,

a current flows, and a lightning flash occurs.

The flash produces an abrupt reconfiguration

of the electric field.

In some cases a surge of electrons rushes

towards the upper part of the storm,

at speeds nearly as fast as light.

When deflected by air molecules,

these accelerated electrons give off gamma rays,

producing a TGF.

Data from NASA's Fermi Gamma Ray Space Telescope

suggests more than a thousand TGFs occur each day,

all over the globe.

Tropical storms far from land tend to generate

less frequent lightning.

Nevertheless, observations show they are

surprisingly prolific producers of TGFs.

Tropical storm Manuel made landfall just shy

of hurricane strength.

As it rapidly weakened,

it produced two TGFs within 24 hours.

More typically, TGFs are associated

with a strengthening phase of a storm.

As Typhoon Bolaven rapidly developed in 2012,

thunderstorms nearly 500 miles from its center

launched a TGF with four distinct pulses.

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So far, the record holder for TGFs

is the rapidly strengthening tropical wave

that later gave birth to Hurricane Julio.

It produced four TGFS within 100 minutes,

a fifth followed the next day, with nothing further.

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For stronger storms, like hurricanes and typhoons,

TGFs are more common in the outer rain bands,

which hold the highest lightning flash rates

in these storms.

The findings provide new insights

into the relationship between storm intensity,

lightning frequency, and TGFs.

This adds another piece to the puzzle

of our understanding of TGFs, and how they are created

in thunderstorms,

the most powerful natural particle accelerators

on planet Earth.

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- Ultimately the science that we learn

from GOLD and ICON will help us

be able to predict the near-Earth environment

that affects our communication and navigation signals

and capability, but also, how space weather affects

the upper atmosphere, which can translate

to effects on the ground, in terms of our power systems,

and our navigation systems down below.

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- [Narrator] The march of technology must go on.

ESA in the European Union can see the future

of global positioning, and it is a growing market,

with more and more technology requiring their services.

The Galileo program is nearly completion

with a total of 26 satellites,

orbiting at 22,000 kilometers.

The penultimate launch of four Galileo satellites

about an Ariane 5 will occur soon.

As with all other Galileo satellites,

these newest additions will fly in a medium-Earth orbit.

The last launch of four satellites

will occur in the near future.

Although the Constellation is not yet complete,

it has been in operation for almost a year,

since the European Commission announced

initial services on the fifteenth of December, 2016.

- The completion of the Constellation

will take place in December of 2018,

where we launch the last Ariane 5 with four satellites,

which will bring the total up to 26 satellites.

So we have, at that moment, two satellites in reserve,

and we will then, after that, start putting some extra

reserves in space in order to be prepared,

just in case.

- [Narrator] These services were the first step

towards full operational capability.

And the first opportunity for the Galileo system

to prove its worth.

- [Woman] Goal!

- [Narrator] Independent measurements have since shown

that in terms of performance,

Galileo is the best operating position system

in the world.

- On the fifteenth of December, 2016,

the Commission announced initial services,

this was an important moment because this was

the first time that we formally announced

that there was a certain service available

with a certain quality for a certain time of the day.

Since then we have been building out

the Constellation and it has been improving every day.

We now have independent measurements of the performance

of the Galileo system and it is actually,

to be honest, and we are very proud of it,

the best in class.

We are having a better performance

than our three competitors from the US,

which is well known GPS system,

the Russian GLONASS system,

and the Chinese BeiDou system.

So of course, in ESA, we are excessively proud of this,

and it is now important that we keep building

on this performance,

and to hopefully keep at the forefront

of the developments.

- [Narrator] But the work on Galileo

is far from done.

The European Commission and ESA

are already working on the next generation

of Galileo satellites and infrastructure.

They aim to continuously improve the system,

and explore the boundaries of technological possibilities,

while trying to meet market demand,

with potential new applications of services.

- The system will undergo continuous improvements.

Obviously the market is asking for that,

the technology is ready for it,

every couple of years there are new possibilities.

And the combination between what technology

can offer and what the market is demanding

leads them to decisions on how to improve

the system, so that we can provide further

and more services.

A number of areas, for example,

which are coming is the so-called internet of things,

which will require positioning in sensors,

and the sensors have very little power

and very little battery capacity,

so we need special signals for that, probably.

And in addition, another area which is of interest

is autonomous driving, where satellite navigation

is going to be a very important component,

but where it needs to be integrated

with all sorts of other sensors in cars

in order to make sure that autonomous driving

becomes a reality.

- [Narrator] With more launches to complete

the Constellation and setup redundancies,

Galileo's performance and availability worldwide

will continue to improve gradually,

keeping Galileo at the cutting edge

of satellite positioning technology.

Today, the only publicly owned satellite system

has also proven to be the best.

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