Original subtitles

(tense music)

It's spinal tap.

Everything's turned up a little bit closer to 11.

Jupiter is enormous.

And everybody loves 11.

(dramatic music)

The great red spot, the drama of the poles,

and all the vortices going around.

It's got these fantastic cloud layers spinning around.

These storms raging bigger than the Earth itself.

And then the moons!

It's like a little solar system in itself.

Instead of a starred center with planets going around it.

You've got Jupiter with moons going around it.

79 moons.

Four big ones.

Io, Europa, Ganymede, and Callisto and they are huge!

Each one their own world of ice, or rock, or volcano.

It's a very violent, dangerous,

deadly place in the solar system.

(dramatic music)

You send a spacecraft to Jupiter,

you're gonna get fried really quick.

(machine whirring)

Can we send a spacecraft through that environment?

The Greeks weren't wrong to make

that thing the king of the gods.

(dramatic music)

(gentle music)

Juno was gonna be the first spacecraft

to fly over the poles of Jupiter,

and it was due to arrive on the 4th of July.

(dramatic music)

That day I had my whole family.

We were going into JPL.

I remember turning to my kids in the backseat and said,

"It might not work something bad could happen.

"NASA and the country and the world

"are taking a big risk here."

We had no idea what this polar environment was like.

We had some sense of the radiation belt.

We knew they are nasty,

really, really nasty.

(dramatic music)

Juno is an armored tank,

but it's nothing compared to Jupiter.

So we want to be really careful.

Go through quickly and get out.

And so, Juno is moving really fast.

It was coming in at about 150,000 miles an hour,

which is like going around the Earth

five times in two hours.

Not because we had this incredible prolusion system,

but because Jupiter's gravity was sucking us in.

(dramatic music)

The engineers hoped that it wasn't gonna get us completely.

We were gonna just go really close to it.

(dramatic music)

If it doesn't work, it's over.

Lights off.

(insects chirping)

Long before Juno would make its daring attempt,

scientists had begun to realize

that it was an unusual region of space.

(dramatic music)

Back in 1955, they detected bursts of radio emission

coming from Jupiter, and they didn't know what it was.

(dramatic music)

It's like a gigantic engine, and the amount of energy

that must be just bopping around that thing is amazing.

But this told us that Jupiter has a magnetic field,

and perhaps, more importantly, a very strong one.

Some planets have a dynamo inside,

which means they behave like a giant spinning magnet

surrounding them with a magnetic field.

Early on, little was known about

what these magnetic fields could do.

Then in 1958, an experiment

would begin to reveal the secret.

At the end of the 1950s,

there was a huge push in America

to have a successful satellite in orbit,

and the concept of the Explorer 1 mission was developed.

Now the scientific payload for that mission

was led by a person called James Van Allen,

who had a big interest in magnetic fields

and the particle environment

that might be above our heads in space.

(dramatic music)

One of the things that he was excited about

was really high-energy particles,

and so he proposed an instrument to be on Explorer 1,

our very first spacecraft.

So Explorer 1 had a very simple detector system

that would count particles.

It was a Geiger-Muller tube,

the kind of thing you look for radiation with.

It does the click, click, click counting for radiation.

They wanted to fly this on the rocket

to measure the radiation up in space.

The experiment was looking for cosmic rays.

Now cosmic rays are the radiation coming out

from far out in the galaxy entering our solar system.

And it went up there.

They're counting the particles, zip, zip, zip going in.

At some point though, the signals disappeared.

(machine whirring)

At certain altitudes,

particularly around about 2,000 kilometers

above the surface of the Earth,

the count rate dropped to zero.

They thought, "Ah-ha, you know what's happening.

"This is saturated.

"The number of particles are so high

"that the detector has just said I'm gonna shut down."

(dramatic music)

That realization actually led to a phenomenal discovery.

In space there are donut shaped regions around the Earth

where there are many, many electrically charged particles,

for example, electrons

and other electrically charged particles.

The radiation gets trapped into this really

lethal zone around the Earth.

They're trapped because electrically charged particles

feel a force from the magnetic field.

We had discovered that the Earth's

magnetic field creates a bubble around the planet

called a magnetosphere sphere,

that both deflects charged particles

and captures some as well.

Many of these particles of radiation

come streaming from the sun,

and this is called the solar wind.

The scientific discovery is fantastic on the one hand,

but it's also slightly worrying.

Because high-energy charged particles can pack a punch

when they interact with materials.

So let's imagine, for example, the impact on the human body.

If these particles have enough energy,

they can penetrate the skin

and start to interfere with the cells of the body.

So in an extreme case,

you might get radiation sickness if you had enough

high-energy particles coming into your body.

(dramatic music)

We have to be really careful, not just because of humans,

we don't want to be damage but also the electronics.

So can we send our spacecraft to places like Jupiter?

Will our spacecraft survive in those kind of environments?

(dramatic music)

When Van Allen discovered these incredibly

high-energy radiation belts around the Earth,

I think, people started to then look at the models

of what would be needed at Jupiter

to explain what was being observed?

All of a sudden like pieces of a puzzle,

the ideas started to come together.

The calculations started to be made,

and people were startled because Jupiter

was so much more powerful than the Earth.

I mean, our radiation belt, as severe as they are

and dangerous as they may be, are really a piece of cake

compared to Jupiter.

(gentle music)

So the first time we left Earth

to go out in the solar system

beyond the orbit of Mars, there were major concerns.

Can we send a spacecraft through that environment?

So we sent two Pioneer space rockets.

They were pretty crude

with very limited computational capabilities

and very limited power and ability to communicate.

So they would just make a few measurements,

and then send the information back to the Earth very simple.

(funky electronic music)

So when the Pioneers flew

through the magnetosphere of Jupiter,

we didn't know how big this was.

We didn't know how large the magnetic field is,

and we didn't know how it was shaped

or buffeted by the solar wind.

(dramatic music)

Pioneer 10 was due to fly past Jupiter

on the 3rd of December 1973,

and these are some of the first images it sent back.

(dramatic music)

Pioneer carried some protection,

but it probably went a little bit

closer than it should have.

But it was zipping through pretty fast.

In order to try to assess what it was like there,

I mean, it basically was carrying a Geiger counter.

I think, everybody was startled

at the amount of energy that we're talking about.

During its closest approach to Jupiter,

Pioneer 10 absorbed 1,000 times

the lethal dose of radiation for a human being.

The spacecraft is collecting

its worse radiation exposure.

Tension is even greater this time

and so is the relief. (people applauding)

R-10, R-two.

Makes it all worthwhile.

After 10 years of having to put with all these people

and 14 hours a day it's all worthwhile.

(gentle music)

And so, after the Pioneers we knew the extent

of the Jovian magnetosphere, and it is enormous.

(dramatic music)

If we could see it in the night sky

with Jupiter sitting rather far away from us,

it would still be roughly five times larger than the moon.

I always wished it could be like a light purple

traveling through the sky, and it would just be huge.

The solar wind that hits that magnetic field

shapes it like a comet and produces a long tail.

The tail stretches all the way to Saturn.

(dramatic music)

The primary purpose of those Pioneers was really to say

can we survive this lethal dose of radiation,

so then we can follow with more sophisticated

instrumentation that can do a lot of interesting science.

(lively drum music)

I was lucky to start working on Voyager

as a graduate student at MIT.

It was the first project that I worked on.

I came along just as we were about to launch the spacecraft

on its way out first to Jupiter.

I got a job as an undergraduate assistant

to the imaging team.

It was a mind blowing experience in so many ways.

We had the Voyager spacecraft down

at the Cape ready to launch.

It was the Pioneer data that made us realize

that the radiation tolerance that we had designed

into the Voyager spacecraft was not gonna be adequate

for the environment that Pioneer 10 and 11 had sensed.

It threw us into a real turmoil

of trying to recover from that.

(funky guitar music)

By the time we got to the Voyager spacecraft,

we were already so scared and intimidated by Jupiter

that we started to move away from it.

We didn't wanna get so close

because we knew if you got close,

you're probably spelling the end of the spacecraft.

So you've gotta stay away and respect this beast.

This monster it's much more powerful than we are.

Even with a quite small telescope from your backyard,

you can look up and see Jupiter on a clear night,

and you can see the belts and zones.

You can see the red spot.

(funky upbeat music)

But Voyager saw up close

and making a movie as it approached.

(funky upbeat music)

It was really like you were

on the spacecraft looking out the window.

You could see these belts and zones,

east, west winds going back and forth,

and the great red spot being caught up

in those belts and zones.

So the weather system was becoming clear.

As we flew by, we could get a real sense

of how this dynamic atmosphere was working.

(gentle music)

As we come in for a close view of Jupiter,

you'll see clouds orbiting around the planet

at different rates, with different thickness bands,

and these are called the jets.

These jets go around lines of latitude, back and forth,

some faster than the planet, some slower than the planet,

and so if you were living on the planet,

there'd be these huge sheers at different latitudes

as these fight back and forth in different directions.

Finding out what causes this wild weather

became a key scientific objective.

On Jupiter the affects of planetary rotation

are incredibly important, why?

Well, the strength of the rotational forces

depends on how fast the system rotates,

and it also depends on how big the system is,

and Jupiter's huge.

Jupiter has a diameter of a 140,000 kilometers

and it was discovered that the planets rotates

at about 40,000 kilometers per hour.

So this body is just completely flying.

If you think of the whole planet as a gyroscope,

it would be a very big, very fast gyroscope.

Those gyroscopic effects dominate

many of the dynamics we observed.

We use this demo to explain Jupiter's great red spot,

which is a really interesting phenomenon

that we've observed for over 200 years,

and we think it's existed longer than that.

It's, essentially, a massive hurricane

that's about 1.3 times the size of the Earth.

In this experiment you're looking at

a simplified analog of the surface of a gas giant.

The cloud layer it's only about

five or six centimeters deep and a meter across,

and we faked the photo chemistry with

sprayed in food coloring.

(funky upbeat music)

So Jupiter is very strongly rotating body,

but it also has a lot of strong turbulence.

The great red spot has formed

from this rapidly rotating turbulence.

Instead of having the massive turbulence

that's naturally occurring in Jupiter

by the hand of God, we just mix a little.

As a cloud of gas or liquid

moves across a rotating surface,

its path begins to curve along with the rotation.

This is called the Coriolis effect,

and it's what spins hurricanes and typhoons here on Earth.

But because Jupiter is so large and turns so fast,

its weather is far more extreme.

The affect of the Coriolis force

in the presence of turbulence

acts to generate large scale structures,

like the great red spot, and they persist.

But now what you're seeing in the tank

is the formation of these beautiful vortices.

You can see there's all these filaments connecting them.

That's what you get in rotating systems.

You naturally role things up

into large vertical structures.

(funky upbeat music)

They live a long, long time

when the system's rapidly rotating.

If the planet stopped rotating,

that organization would be gone.

(dramatic music)

The Voyager spacecraft were not

just visiting Jupiter in order to examine the planet.

The four giant Galilean moons were a key objective,

and none more so than the mysterious moon Io.

(dramatic music)

As we were coming in,

the ultraviolet instrument was saying,

"Whoa, this is bright.

"Whoa, there's a lot of gas around this environment near Io.

"You better be careful."

(dramatic music)

Voyager flew by and we saw it covered with volcanoes.

We saw gases spewing out

hundreds of kilometers up into the sky,

and so now we began to make sense what was happening.

That these volcanoes were spewing out gases

about a ton every second.

Those gases were becoming trapped in the magnetic field

to make this donut of charge particles.

They get accelerated to very high energies.

(dramatic music)

Most of them go out to fill a big volume.

Some of them go in, and as they go in,

they go to even higher energies

and form this very tight environment close to Jupiter,

this lethal radiation environment.

That inner region is very analogous

to the Van Allen belt of Earth

but many times stronger and more nasty.

The background radiation here on Earth

that we're exposed to is about a third of a rad.

At Jupiter, the radiation environment is 20 million rad.

We did know Io, Europa, Ganymede

are in these orbital residences

where Io goes around four times

for every two times and one times

that the others go around.

The orbits are elliptical,

and so when Io was close to Jupiter, it squeezes it.

When it's further away from Jupiter, the squeeze is less,

and so you're literally looking at Io going like this.

That heat has got to go somewhere.

There'd been a paper published in science magazine

that had come out the week before Voyager got there

predicting volcanoes on Io because of this tidal flexing.

(dramatic music)

But, we were not expecting what we saw with Voyager.

(machine beeping) (gentle music)

Everybody thought the Io was the cool neat one

and the others were okay.

(gentle music)

We knew there was something weird about Europa.

It was bright and maybe it had these weird markings,

but you couldn't really see them before.

(gentle music)

Then all of sudden there it is,

and this first image is appearing on the screen.

Europa has all these cracks in the ice

and these lines going across.

They're gonna be two.

Io and Europa there's a twin.

At that moment it was just like whoa.

What does that mean?

(gentle music)

As an airless body, we kind of expect

things to be bombarded all the time, so you end up

with a surface peppered with craters much like our moon.

What about the relief in the cracks?

Because the cratering rate throughout the solar system

is relatively well understood,

the fact that Europa has so few craters

is very consistent with it having a young surface,

with a surface that has been geologically resurfaced.

Carl Sagan who was there in the room

he said, "Ah, Percival Lowell was right.

"Only the canals are on Europa not Mars."

Now this is something we keep discovering

in planetary science.

We thought the moons of Jupiter would be

all dead and boring, and they're not

because there's a mysterious unknown energy sources.

(scientists chatting)

It's like, "Oh, wow, there's more going on here

"than we thought with our Earth-based assumptions."

(upbeat music)

The Voyager observations were so spectacular,

the dynamics of the atmosphere,

the different kinds of moons and what was going on.

Everybody said we gotta go back.

But this time we have to go back and stay.

With Voyager we had a couple of

very short fleeting flybys.

Like just whizzing some pictures

out your car window as you drive by,

as opposed to actually stopping,

getting out of the car and exploring.

We have to go into orbit send a probe into the atmosphere.

Find out what it's like inside.

Go past all the moons

and look at them in different directions.

(upbeat music)

Before the Voyagers had Jupiter

in their rear view mirrors,

NASA had been building a spacecraft they intended

to go into orbit around the giant planet.

The mission was called Galileo.

Galileo had a fitful start right from the very beginning

about how exactly it was going to get to Jupiter.

Galileo was scheduled to launch

in January 1982 onboard the space shuttle.

The launch date slips to '84, then '85, and then '86,

and then the whole shuttle program

suffered a terrible tragedy.

(somber music)

The spacecraft was down at the Cape.

I can remember looking out the window

of the Challenge launch.

Challenge go with throttle up.

The significance of that, of course, the loss of life

and a disruption of the whole program,

but to us was we didn't have a launch vehicle.

And so, we packed up our spacecraft

and took it back to California

trying to figure out what to do.

Not only was the launch delayed,

but after the accident,

NASA was understandably more risk averse.

The liquid hydrogen fueled rocket booster,

which was originally planned to deliver

the Galileo mission directly to Jupiter,

was no longer deemed safe enough.

It was no longer possible

to take Galileo straight up to Jupiter,

and that's where the mission designers here

pulled a rabbit out of the hat

and found the so-called VEEGA,

Venus Earth Earth Gravity Assist trajectory

that took another five years to get there.

(crowd applauding)

We have a go from main engine start.

Six, five, four, three, two, one.

We have ignition and lift off of Atlantis

and the Galileo spacecraft bound for Jupiter.

(gentle music)

(astronauts chatting)

Galileo is on its way to another world.

Fly safe.

After the first flyby,

we knew we would be far enough away from the sun

that we could actually begin to use the high-gain antenna.

(gentle music)

It was like an umbrella.

You imagine an umbrella being folded up.

Then when the time came

when the spacecraft would fire a device,

and then the antenna could unfold.

So we accentuated the motor to free the antenna

and it stuck.

(bright music)

If you imagine. (imitates machine whirring)

It stalled only partially deploying some of the antenna.

(bright flute music)

The motor doesn't reverse.

We could tell the antenna had deployed a little bit

because the spacecraft's spin wasn't quite the same.

It's like if you stick out one arm and you're spinning

you start to do this a little bit.

Well, the antenna was doing that a little bit.

So we knew it opened some.

So why didn't it open?

Well, we understand now that the reason it didn't open

was because of the combination of the fact that

the antenna had remained stowed for so long,

and the fact that it went in

from two vibrations environments.

Once when we latched this spacecraft up in California,

trucked it down the Kennedy.

Challenger didn't work.

Put it back in the truck.

Trucked it back to Pasadena.

Said, "Let's not mess with that antenna.

"It was all put together right.

"We'll just leave it the way it was."

Back to Cape again.

So it made three trips across the Cape

in a truck which was vibrating the whole time.

(bright music)

And so, we did a lot of things.

We worked on calibrating how far the antenna was open.

Could we use it the way it was,

and could we do the cold turns to free it up

and see if anything springs free?

We'd know again by seeing the spin rates change

if anything broke free.

So we spent a couple of years working on those things.

JPL never did get

the high-gain antenna to open.

Our capability at Jupiter

with an antenna that hadn't opened

was gonna be dependent upon a single low-gain antenna.

That just meant we had to transmit

a lot fewer picture over the same time.

But, overall reduction and mission return

was large but not disastrous.

(dramatic music)

The Galileo spacecraft carried along with it a probe.

It's sort of like this size.

It had a big heat shield to protect it around it.

In July 1995, we launched that probe

and sent it in the direction of Jupiter.

Now it didn't have engines,

so we weren't guiding it and saying go there.

We just sort of sent it on a trajectory towards Jupiter.

Five months later on the 7th of December 1995,

the Galileo probe was due to arrive at Jupiter.

(dramatic music)

There were no cameras onboard only censors

and a little probe that was going to have

an extremely violent introduction to Jupiter.

It was coming in at something like

a 130,000 miles an hour

because it was pulled in by the gravity of Jupiter,

and we had to slow it down.

This heat shield heated up to about three times

the temperature of the surface of the Sun.

(dramatic music)

During its maximum deceleration

the probe endured forces of 228-Gs.

Then eventually we kicked off that heat shield,

put up some parachutes,

and so as it went down,

we were able to get a sense of what it was like.

What we were expecting was three separate layers of clouds.

(dramatic music)

And we went down it was like, "Where are the clouds?

"Where are the clouds?

"We're not seeing the clouds what's going on?"

So everybody was completely confused.

Well, the hint came from the ground.

Telescopes on Earth were looking in the infrared

at Jupiter at the same time we sent the probe in.

We realized that the probe went into a hot spot

somewhere where there's very little water.

I think, we realize that our whole idea

of exploring these planets with single probes

is a little bit susceptible to going into the wrong place.

By the time the probe had got down to about 160 kilometers

something like 23 times atmospheric pressure,

it was now starting to get really hot,

and so at that point the electronics

is just not working anymore.

It stops communicating and sending signals back to Earth.

What happened to it after that?

Well, it was so hot that it basically vaporized.

But let's imagine what it will be like

if you could be a pressured capsule as you get deeper down.

(thunder rumbling)

I mean, it's either a hang glider's nightmare

or his dream depending on how risky they wanna be.

But as you went deeper and deeper,

it would get a little calmer, a little less turbulent.

The pressure would get higher and higher.

It's so hot everything's vaporous.

Eventually, you get down to material

that are almost like rock clouds,

and they're probably precipitating.

Now when you get down something like 10% of the radius,

you're now getting to the point where the pressures

are about a million times Earth's atmospheric pressure,

and the density is getting really high.

At that point hydrogen changes its phase.

It's no longer molecules,

protons and electrons connected together.

But the protons and the electrons are moving separately,

and it becomes metallic.

That is it becomes electrically conducting.

In this region you can generate a magnetic field,

what's called a dynamo.

The fluids convert some of their motional energy

into magnetic field energy, into currents.

(dramatic music)

On Earth the dynamo is very far from us.

Earth's core is halfway through the planet.

But on Jupiter you don't even go 10% of the way in,

and you've got this 60,000 kilometer radius ball

of molten metallic material.

(dramatic music)

Maybe that means it's not amazing

that you generate a huge magnetic field.

I suspect it would look like Mercury.

A glob of Mercury is what it will probably look like.

(dramatic music)

If you existed, you would be

unbelievably thin, flat out pancake.

You get to the center of Jupiter we're talking

four times the temperature of the surface of the Sun,

50 millions atmospheres pressure,

and a density that's denser than the heaviest

metals that we have on Earth.

Now the Galileo probe

had succeeded with its mission

and subsequently vaporized inside Jupiter,

the mothership had to avoid a similar fate

and insert itself safely into orbit.

In just that first pass when we were getting into orbit,

Galileo received half of its radiation dose,

like a 150 kilo rads in one shot.

Then it went out further and kind of licked its wounds.

Because of Galileo having this broken antenna,

it meant that we couldn't make all the observations

of Jupiter that we wanted, the movies and so on so forth.

We had to be selective.

Remembering that we don't wanna get

into the radiation belts too quickly,

so we tended to focus further out first.

The first really exciting thing we found

was Ganymede has its own magnetic field.

The seventh moon out

from the surface of Jupiter,

Ganymede, is a moon the size of a planet.

Larger than Mercury,

it's the biggest moon in our solar system.

The fact that Ganymede has a magnetic field,

means that it might have some ability

to protect itself from the harsh radiation of Jupiter,

a key attribute for a habitat where life might be found.

So now it starts to open up

how we think about even what's a planetary body?

These moons how different are they from other planets?

They can have their own magnetic field.

(dramatic music)

But now the Galileo spacecraft,

despite its troubles, was about to make arguably

the most important discovery in the history of space flight

at the mysterious moon that Voyager

had visited 17 years before Europa.

What we measured as we flew by

was something quite remarkable.

There were electrical currents

that were flowing inside the moon

that perturbed the magnetic field,

and we concluded that Europa has to have

a liquid ocean underneath that ice.

(dramatic music)

The reason is, ice is not very electrically conducting.

You need it to be liquified as water in a big ocean

to carry those electrical currents.

Probably has to have salt in it

to be electrically conducting

in the way that the Earth's salty ocean

is electrically conducting.

The reason why we hardly see any craters

on the surface of Europa,

is because that ocean is squirted out

and has filled them in over time.

Like Io, Europa,

which is also in an elliptical orbit

gets squeezed and relaxed every two or so days

as it goes around the planet,

is dissipating that heat by melting that ice shell.

We believe the ocean can be as thick as a 100 miles

and maybe even thicker.

At the rocky surface at the bottom of the ocean,

I know exactly what it looks like.

It looks like Io.

We call those molten volcanoes on Io,

but underneath the ocean in Europa

we would call them hydrothermal vents.

Such vents are also found here on Earth.

Those hydrothermal vents form fields.

So it's not just a single chimney.

But there's a field of chimneys, if you like,

and those fields we think on the early Earth,

and potentially on some moons,

could spread across an entire sea floor

the ones we're interested in,

and they are not black smokers,

which are kind of chimneys with black smoke

belching out of the top.

It's a different type of vent.

The hydrothermal fluid are warm, not hot, and alkaline.

They look almost deserted.

But they are chemically active.

You have this kind of porous lathering

sort of interconnected pores.

Sort of hydrogen from the vents

mixing with CO2 from the oceans,

making organic molecules.

Here you have a setting which looks an awful lot

like the way that modern cells work.

This kind of chemistry was almost certainly behind

the origin of life on Earth.

(liquid sloshing)

(gentle piano music)

When you look at Europa and you look at the cracks,

there is this brown gunky stuff

that seems to be coming from the interior.

But also could it be that there's a source of chemistry

coming from Io, in Io's volcanoes,

impacting the surface of Europa bringing sulfur,

and perhaps more importantly oxygen, into Europa,

and that material then gets carried down into the ocean,

oxidizing the environment of the ocean,

and maybe enhancing the life that maybe is there.

Maybe not, we don't know.

I think that Europa is a place where,

given what we think we know about life,

there ought to be life.

But it is the most likely place.

If you wanna go somewhere in the solar system,

to find out if there's life, that's where I'd put my money.

After the incredible discovery at Europa,

the Galileo mission found that Ganymede

also had a sub-surface ocean,

and there's was strong suspicions

that Callisto might contain an ocean as well.

We had no idea that life could exist

anywhere else in our solar system prior to this.

It was just we have life on Earth,

so to get life anywhere else you need to have planets,

and other star systems that look just like Earth.

I think, we're realizing now that there

are other places even within our solar system

that you can have these right ingredients

and have energy and these primordial ingredients

that is required to actually make something complex

out of randomness, essentially.

(dramatic music)

Galileo made a lot of incredible contributions

to our understanding the whole system

and how it interacts with each other.

What was really going on as Io spit out all this material,

Ganymede had its own magnetic feel.

Europa had an enormous ocean.

But by then we'd kind of done

what we were gonna do with Galileo.

The radiation of Jupiter

is very, very hard on electronics.

So it upset the spacecraft.

It goes into saving, stops all the sequences,

and you have to restart things.

After having its mission extended three times,

it was eventually decided in 2003

to dispose of the aging radiation damaged spacecraft

by flying it into the clouds of Jupiter.

We learned so much from Galileo.

In fact, it was really the results of Galileo

that led us to Juno.

Lift off of the Atlas V with Juno

on a trek to Jupiter.

The big question after Galileo

was did not probe just go into somewhere weird

or was the lack of water symptomatic of the entire planet?

Now this is extremely important.

In 30 minutes that it took the probe

to go into Jupiter and get this data,

every theory of solar system formation was proven wrong.

Because remember we think that gas giants formed by having

giant snowballs, say 30 times the mass of the Earth,

that pull in the hydrogen to make the gas giants.

So at the core we think there was ice.

Yet, when we went in with that probe,

we didn't see any or very little.

So what's going on?

So when Juno came along,

one of its primary objectives

was to go in and see how much water

and oxygen is in Jupiter.

We have to go back and find out.

We could send in a 100 probes.

But, that's gonna be expensive and difficult.

We thought of a cleverer way of doing it.

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Juno was designed in order to make measurements

almost over the whole planet and look at the water

rather than in one spot,

and to go much deeper remotely not with a probe.

The brilliant idea was to use microwaves.

Everyone knows that microwaves are absorbed by water.

So what we want to do is fly over Jupiter

and map out the distribution of water

from the absorption of those microwaves.

But to find out what it's like deep inside,

we have to measure distribution of mass inside

that changes the gravity field in some subtle ways.

To do that we had to go into a polar orbit,

and we also had to get really close.

Now remember we've got a problem with Jupiter.

Jupiter has these radiation belts around it.

You don't really wanna take your sensitive electronics

of your spacecraft through that environment,

at least not for long.

We had to somehow get beneath the radiation belt.

If we can just thread that needle.

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I was just praying with my eyes closed

that this was gonna work.

We were getting a few thousand miles above the cloud tops

when we were doing this maneuver.

Nothing had ever been that close.

Fire the engines.

Go head now.

Yeah, we see the action has started.

Copy that, that's good news for us.

(people applauding) Thirty-five minutes

they're firing away slowing down the spacecraft,

so it gets caught in Jupiter's gravity.

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And when we find out spacecraft's alive, phew, big relief.

(people applauding and cheering)

Juno welcome to Jupiter.

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NASA did it again.

(crowd applauding and cheering)

You know the thing that was also sobering

was we were coming back, this was our game plan.

Every orbit we were gonna have to

run through that fire with our bare feet.

Juno carried a camera called Juno cam

designed to provide pictures for the public back on Earth.

But these images were too reveal a great surprise.

Our view of Jupiter before Juno was from the equator.

So then when Juno flies over the poles and is looking down,

and there we see these vortices, all this structure,

it's just extraordinary.

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The Juno cam that little camera that was just slapped on

to get some publicity photos

has turned out to be just extraordinary.

I'd love to say that I figured this out

and did it on purpose,

but really what I wanted was a great picture.

Little did we know that the poles of Jupiter

were gonna become this huge science discover by itself.

Giant polar cyclones nobody anticipated that.

With the help of the citizen scientists around the world

helping us process those images

we are seeing all sorts of little structures,

and pop up you clouds.

Nobody expected that level of detail.

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When we fly in close measuring

the perturbations in Juno's motion,

we're beginning to get a sense of what it's like inside.

What we're finding is that

it's not like the textbook picture

where you have a metal rock core inside

and then a layer of hydrogen, and then a layer of gas above.

It's much fuzzier, much more mixed up,

and so, in fact, that core

is spread out to about 40% of the radius.

It's mixed in with the metallic hydrogen.

You're beginning to see that the convection system

we see on the outside extend a long way in.

They're much, much deeper.

(gentle dramatic music)

But what Juno has not yet been able to explain

is what drives the jets?

It might be that turbulence

at the surface drives these jets,

and then the jets burrow down into the depths.

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But with Jupiter so much heat is coming

out of the interior of the planet,

that maybe the jets are being driven by deep motions,

and it's their surface expression

that we're seeing about the top.

There's probably something deep down

is driving a lot of motion inside of Jupiter.

We're beginning to think about that region

where hydrogen becomes metallic

that generates this strong magnetic field.

The magnetic field is probably moving things around.

Driving convection and eddies and all kinds of motion,

and so somewhere there's a balancing act.

The stuff that's coming in from the top

meets the stuff that's coming up from the bottom,

and all hell breaks lose.

What's the right answer?

We do not yet know.

Open question.

One of the great questions for me

as a scientist looking at Jupiter and studying Jupiter.

Nobody really knows for sure what makes the colors

in Jupiter's zones and belts.

We see all these oranges and reds

and beautiful yellows and browns.

Io spewing out tons of sulfur among other things

because it's volcanic.

Models sort of indicate to us that

as I radioactively change sulfur,

it can make these reddish hues,

and so Io may have had a huge effect

on the way Jupiter appears to us.

But it's producing a lot of material

that's definitely going into Jupiter,

and it may be part of the reason that Jupiter

is this incredibly beautiful object.

So in many ways the combination of Io

and its volcanoes with Jupiter's strong magnetic field,

is really at the core of an engine or a generator.

(low rumbling) (dramatic music)

(gentle music)

When we laid out the objectives of Juno,

it was to go sort of figure out the puzzles

of what it was made out of and how it formed.

Nobody really conceived of the idea that we'd go there,

and the entire structure was gonna be

different than we thought.

(gentle music)

It may be that we've been a bit naive.

That if Jupiter could throw us this many curve balls,

that our ideas of how stars worked

could be kind of wrong too.

I mean, there's even more energy,

and they're even more massive.

Astronomers have looked out and seen many stars,

right, billions, and billions.

Many of those are binary systems,

two stars going around each other.

Sometimes there's a big star and a little star.

Maybe a star that has only a tiny bit of fusion inside

like a brown dwarf.

In our case and many others we've seen

where we have a star and a planetary system,

the biggest planet does not have enough mass

to have a fusion reaction inside.

So let's think of our solar system

where we have the sun and we have Jupiter.

Jupiter is 1/1000th the volume

and 1/1000th the mass of the sun,

and so it's too small to have fusion inside.

It's a failed star.

But it's a very successful planet.

(dramatic music)

Juno continues to explore Jupiter

diving beneath the lethal radiation belt

on every daring orbit,

and each time we learn a little more about

the greatest planet in the solar system.

But we have unfinished business with some of its moons.

JUICE is the next major exploration mission

for the European space agency.

Jupiter, icy moons, explorer.

Its sole purpose is to go to Jupiter

and explore the icy moons.

The main aim is really to try and understand

what they look like below the surface,

how thick is the ice layer,

how deep is the subsurface ocean.

NASA has been funding a mission called Europa Clipper,

which will take a number of flybys of Europa

to try and get a deeper investigation

of what might be happening on the surface,

even a basic understanding of some

of the chemistry that might be there,

in preparation for investigations yet to come

getting down to the oceans.

For places like Europa, Ganymede,

getting below the ice layer is the holy grail.

Getting into that subsurface ocean

that is a whole new frontier,

and that will be a fascinating thing

if we can ever achieve that.

Well, the first challenge you have

is actually getting down through the ice.

While people have talked about drills and other such things,

we wanna reduce this 20-kilometers of ice

as much as possible,

and so we've built submersibles

that can actually navigate through tunnels and canyons

to be able to try and make their way down through perhaps

these open crevices as close to the water as possible.

Now if we can get into the water itself,

we've built a buoyant rover that goes underneath the ice

and floats so it drives on the underside of the ice

exactly at that ice water boundary on there

by turning the camera to look up at the microbes

that we might find there on the underside of the ice.

Then we've been working on deep ocean vessels

where we hope to go down to the bottom

of the ocean on Europa,

and then bring back samples to us

of what might be down at the bottom of the ocean.

JUICE doesn't launch till 2022.

It's not gonna get there until 2030.

In the mid-2020s we hope to launch Europa Clipper.

After a 67-year voyage we'll reach Jupiter itself.

(dramatic music)

Some of the people already working on it now

will have retired.

Some will probably have passed away.

What I love about it is that there's this

generational feeling to it.

By the time we get the data,

there will be another generation

of scientists looking at it.

There is an immense opportunity

for us to find the first signs of life

beyond our world in these warm, watery,

rich environments that we are just beginning

to see that we can even access.

The rovers that we're developing

and that are testing here on Earth

are only the ancestors, the far ancestors,

of what we might eventually send there.

(dramatic music)

So, perhaps one day we'll discover life

residing under the ice,

a precious habitat thriving despite

the brutal radioactive environment

in the shadow of the mightiest planet

in our solar system: Jupiter.

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