Jupiter is enormous.
Arnou: It's spinal tap.
Everything's turned up a little bit closer to 11.
Jupiter is cool because it's the biggest planet.
And everybody loves 11.
The great red spot, all the vortices going around.
Patel: These storms raging bigger than the earth itself.
And then, the moons.
It's like a little solar system in itself.
79 moons, four big ones.
Io, europa, ganymede, and callisto.
And they are huge.
Each one, their own world of ice, or rock, of volcanoes.
Bolton: You send a spacecraft to jupiter,
You're gonna get fried really quick.
The greeks weren't wrong to make that thing the king of the gods.
-- Captions by vitac -- www.Vitac.Com
Captions paid for by discovery communications
Juno was gonna be the first spacecraft
To fly over the poles of jupiter.
And it was due to arrive on the fourth of July.
Bolton: That day, I had my whole family.
We were going in to jpl.
Then, I remember turning to my kids in the back seat,
And said, "it might not work. Something bad could happen.
Nasa, and the country, and the world
Are taking a big risk, here."
Bagenal: We had no idea what this pole environment was like.
Some sense of the radiation belts.
We knew they are nasty -- really, really nasty.
Bolton: Juno is an armored tank,
But it's nothing compared to jupiter.
Bagenal: So, we want to be really careful.
Go through quickly, and get out.
And so, juno is moving really fast.
Bagenal: It was coming in at about 150,000 miles an hour,
Which is like going around the earth 5 times in 2 hours.
Bolton: Not because we had this incredible propulsion system,
But because jupiter's gravity was sucking us in.
The engineers hoped that it wasn't gonna
Get us completely.
We were gonna just go really close to it.
If it doesn't work, it's over.
Lights off.
Narrator: Long before juno would make its daring attempt,
Scientists realized
Jupiter's region of the solar system was very unusual.
Back in 1955, they detected bursts of radio emission
Coming from jupiter.
This told us that jupiter has a magnetic field,
And perhaps more importantly, a very strong one.
Narrator: Some planets have a dynamo inside,
Surrounding themselves with a magnetic field.
But at this time, the power of these magnetic fields
Wasn't well understood.
Then, in 1958, an experiment around our own planet
Helped scientists start to understand
The mysterious forces at work around jupiter.
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 environments
That might be above our heads, in space.
Lucie: 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.
Patel: It was a geiger-muller tube,
The kind of thing you look for radiation with.
It counts -- you know, 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, counting the particles --
Zip, zip, zip, zip, going in
At some point, though, the signals disappeared.
Or, aha, 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."
Lucie: And that realization
Actually led to a phenomenal discovery.
In space, there are doughnut-shaped regions
Around the earth,
Where there are many, many electrically charged particles.
The radiation gets trapped into this really lethal zone
Around the earth.
Lucie: And they're trapped because electrically charged particles
Feel a force from the magnetic field.
Narrator: We had discovered that the earth's magnetic field
Creates a bubble around the planet called a "magnetosphere,"
That both deflects charged particles
And captures some, as well.
Critically, many of the radiation particles
Interacting with the magnetosphere
Came streaming from the sun
In what is called "the solar wind."
Lucie: This scientific discovery is, you know,
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.
Bagenal: And so, we have to be really careful,
Not just because of humans we don't want to be damaged,
But also the electronics.
Narrator: As scientists endeavored
To explore further out into our solar system,
One of the main concerns was whether or not
We could build a spacecraft
That would withstand the harsh radiation
Permeating the solar system.
Lucie: So, can we send a spacecraft to places like jupiter?
Will our spacecraft survive in those kind of environments?
Bolton: 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.
I mean, our radiation belts, as severe as they are,
And dangerous as they may be,
Are really a piece of cake compared to jupiter.
♪♪
Bagenal: 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 spacecraft.
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.
♪♪
James: 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.
♪♪
Narrator: Pioneer 10 flew past jupiter on December 3rd, 1973,
And sent back these incredible images.
♪♪
Bolton: Pioneer carried some protection,
But it probably went a little bit closer than it should have,
And in order to try to assess what it was like there,
I mean, it basically was carrying a geiger counter.
And I think everybody was startled at the amount of energy
That we're talking about.
Narrator: During its closest approach to jupiter,
Pioneer 10 absorbed 1,000 times the lethal dose of radiation
For a human being.
Reporter: The spacecraft is collecting its worst radiation exposure now.
Tension is even greater this time,
And so is the relief.
And so, after the pioneers, we knew the extent
Of the jovian magnetosphere, and it is enormous.
Arnou: 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.
James: 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.
Bagenal: 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.
Narrator: The highly anticipated follow-up mission was voyager.
But before launch,
Scientists realized it might have some design flaws.
Casani: We had the voyager spacecraft down at the cape,
Ready to launch, and 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 pioneers 10 and 11 had sent.
It threw us into a real turmoil
Of trying to recover from that.
Bolton: 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 want to get so close,
Because we knew, if you got close,
You're probably spelling the end of the spacecraft.
So, you've got to 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.
But voyager saw up close.
And it was really like you were on the spacecraft,
Looking out the window.
Bagenal: 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.
And so, the weather system was becoming clear.
Arnou: 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."
And 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 would be these huge shears at different latitudes,
As these fight back and forth in different directions.
Narrator: Finding out what causes this wild weather
Became a key scientific objective.
Arnou: On jupiter, the effects 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.
Narrator: Jupiter has a diameter of over 88,000 miles.
It was discovered that it takes just under 10 hours
For the planet to make a complete rotation,
Giving it the shortest day in our solar system.
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.
And those gyroscopic effects dominate many of the dynamics
We observe.
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.
So, jupiter is a very strongly rotating body,
But it also has a lot of strong turbulence.
And the great red spot
Has formed from this rapidly rotating turbulence.
Narrator: 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 here on earth.
But because jupiter is so large, and turns so fast,
Its weather is far more extreme.
Hawkins: The effect of the coriolis force
In the presence of turbulence acts to generate
Large-scale structures like the great red spot.
And they persist.
Arnou: That's what you get in rotating systems.
You naturally roll things up into large vertical structures.
And they live a long, long time
When the system's rapidly rotating.
♪♪
If the planet stopped rotating, that organization would be gone.
♪♪
Narrator: Yet the genius of the voyager spacecraft
Was that they 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.
♪♪
Bagenal: As we were coming in,
The ultraviolet instrument was saying, "whoa, this is bright.
There's a lot of gas around this environment near io.
You better be careful."
Voyager flew by, and we saw it covered with volcanoes.
Narrator: Scientists realized
That io's volcanic gases could be contributing
To the unprecedented radiation surrounding jupiter.
Those gases were becoming trapped in the magnetic field,
To make this doughnut of charged particles.
They get accelerated to very high energies.
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 belts of earth,
But many times stronger, and more nasty.
The background radiation here on earth
That we're exposed to is about 1/3 of a rad.
At jupiter, the radiation environment is 20 million rad.
We did know io, europa, ganymede are in these orbital resonances.
The orbits are elliptical.
And so, when I was close to jupiter, it squeezes it.
And 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 had 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.
Narrator: But io's volcanoes wouldn't be voyager's only lunar bombshell.
You know, 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.
And then, all of a sudden, there it is.
And as the first image is appearing on the screen,
You know, europa has all these cracks in the ice,
And these, like, lines going across.
[ indistinct talking ]
In that moment, it was just like, "whoa.
What does that mean?
Patel: 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.
[ indistinct talking ]
Turtle: 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.
Bagenal: The voyager observations were so spectacular --
The dynamics of the atmosphere,
The different kinds of moons, and what was going on.
Everybody said, "we got to go back."
Bagenal: The voyager observations were so spectacular,
Everybody said, "we got to go back."
But this time, we have to go back and stay.
With voyager, we had a couple of very short, fleeting flybys.
Like, you know, squeezing some pictures
Out your car window as you drive by,
As opposed to actually stopping,
Getting out of the car, and exploring.
Narrator: Before voyager had jupiter in its rearview mirror,
Nasa had been building a spacecraft
They intended to go into orbit around the giant planet.
The mission was called "galileo."
Maize: Galileo had a fitful start right from the very beginning
About how exactly it was going to get to jupiter.
Narrator: Galileo was scheduled to launch in January 1982
On board the space shuttle.
The launch date slipped to '84...
Then '85...
And then '86.
And then, the whole shuttle program
Suffered a terrible tragedy.
The significance of that, of course, the loss of life,
And the disruption of the whole program,
But to us was that we didn't have a launch vehicle.
And so, we packed up our spacecraft,
And took it back to california,
To try and figure out what to do.
Narrator: Not only was the launch delayed,
But after the challenger accident, nasa was rattled.
The liquid hydrogen-fueled rocket booster
That was originally intended to deliver galileo
Directly to jupiter was now considered unsafe.
Maize: 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.
Woman: We have a go [indistinct]
6...5...4...3...2...1.
We have ignition and liftoff of atlantis,
And the galileo spacecraft bound for jupiter.
♪♪
Man: Galileo is on its way to another world.
Fly safe.
Maize: After the first earth flyby,
We knew we would be far enough away from the sun
That we could actually begin to use the high-bream antenna.
It was like an umbrella.
You imagine an umbrella being folded up.
And when the time came,
The spacecraft would fire a device,
And the antenna could unfold.
So, we activated the motor to free the antenna.
And it stuck.
Can you imagine -- [ imitates machinery whirring ]
And it stalled,
Only partially deploying some of the antenna.
And 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 took out one arm, and you're spinning,
You start to do this a little bit.
Well, the antenna was doing that little bit.
So, we knew it opened some.
Casani: So, why didn't it open?
The antenna had remained stowed for so long,
And the fact that it went into 2 vibration environments.
Once, when we latched this spacecraft up in california --
Trucked it down to kennedy, 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 the cape again.
So, it made three trips across the cape,
And the truck was just vibrating the whole time.
Maize: 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?
And 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.
Narrator: Jpl never got the high-gain antenna to open.
Casani: Our capability at jupiter
With an antenna that hadn't opened
Was going to be dependent upon a single low-gain antenna.
And that just meant we had to transmit
A lot fewer pictures over the same time.
Bagenal: The galileo spacecraft carried along with it
A probe, that's sort of like this size.
And it had a big heat shield to protect it around it.
So, 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.
Narrator: Five months later, on December 7th, 1995,
The galileo probe arrived at jupiter.
There were no cameras on board,
Only sensors and a small probe that was going to have
An extremely violent introduction to jupiter.
Bagenal: It was coming in at something like 130,000 miles an hour.
It was pulled in by the gravity of jupiter,
And we had to slow it down.
And so, this heat shield heated up to about three times
The temperature of the surface of the sun.
Narrator: During its maximum deceleration,
The probe endured forces of 228 gs,
And then, eventually, we kicked off the heat shield,
Put out some parachutes.
What we were expecting was three separate layers of clouds.
♪♪
And we went down.
It was like, "where are the clouds?"
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 hotspot,
Somewhere where there's very little water.
And so, I think we realized that our whole idea of exploring
These planets with single probes
Is a little bit susceptible to going into the wrong place.
Bagenal: 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, and it stops communicating,
And sending signals back to the earth.
What happened to it after that?
Well, it was so hot that it basically vaporized.
But let's imagine what it would be like
If you could be in a pressurized capsule as you get deeper down.
It would get a little calmer, a little less turbulent.
The pressure would get higher and higher.
Bolton: It's so hot. Everything's vaporous.
Eventually, you get down to material
That are almost like rock clouds.
And they're probably precipitating.
Bagenal: Now, when you get down something like 10% of the radius,
And the density is getting really high.
And 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.
And 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 current.
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.
And maybe that means it's not amazing
That you generate a huge magnetic field.
Narrator: Now that the galileo probe had succeeded with its mission,
And ultimately vaporized inside jupiter,
The mothership needed to avoid a similar fate,
And insert itself safely into orbit.
Bolton: In just that first pass, when we were getting into orbit,
Galileo received half of its radiation dose --
Like 150 kilorads in one shot.
Then, it went out further, and kind of licked its wounds.
Bagenal: Because of galileo having this broken antenna,
It meant that we tended to focus further out first.
And the first really exciting thing we found was
Ganymede has its own magnetic field.
Narrator: The seventh moon out from the surface of jupiter,
Ganymede is a moon the size of a planet.
Larger than mercury,
It is 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," right?
These moons, how different are they from other planets?
They can have their own magnetic fields.
Narrator: 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.
Woman: We have ignition and liftoff of atlantis,
And the galileo spacecraft bound for jupiter.
Narrator: When the galileo spacecraft launched in 1989,
The mission promised to uncover jupiter's secrets.
But what it revealed about the planet's moon, europa,
Surpassed even scientist's wildest expectations.
Bagenal: 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.
♪♪
And the reason is, ice is not very electrically conducting.
You need it to be liquefied as water, in a big ocean,
To carry those electrical currents.
Probably has to have salt in it
To be electrically conducting,
The way that the earth's salty ocean
Is electrically conducting.
James: And the reason why we hardly see any craters
On the surface of europa
Is because that ocean has squirted out,
And has filled them in over time.
Like io, europa, which is also in an elliptical orbit,
And 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 hundred miles,
And maybe even thicker.
And at the rocky surface at the bottom of the ocean,
I know exactly what it looks like --
Hydrothermal vents.
Narrator: Such vents are also found here on earth.
And those hydrothermal vents span 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.
You have this kind of porous labyrinth
Of interconnected pores, through hydrogen from the vents
Mixing with co2 from the oceans, making organic molecules.
And here, you have a setting which looks an awful lot
Like the way that modern cells work.
And this kind of chemistry
Was almost certainly behind the origin of life on earth.
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, and 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 may -- maybe is there?
Maybe not. We don't know.
Grinspoon: I think that europa is a place where,
Given what we think we know about life,
There ought to be life.
But by then, we've kind of done
What we were gonna do with galileo.
Maize: And the radiation of jupiter is very,
Very hard on electronics.
So, it rips up the spacecraft.
It goes into saving, stops, all the sequences,
And you have to restart things.
Narrator: 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.
Bolton: We learned so much from galileo.
In fact, it was really the results of galileo
That led us to juno.
Man: Liftoff od the atlas five, with juno, on a trip to jupiter.
Bagenal: The big question of the galileo was,
Did that 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.
Bagenal: Because remember, we think the 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.
And 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.
And we could send in 100 probes,
But, you know, that's gonna be expensive and difficult.
And we thought of a clever way of doing it.
Bolton: So, when juno came along, one of its primary objectives
Was to go in, and see how much water and oxygen is in jupiter.
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 the distribution of mass inside
That changes the gravity field in some subtle ways.
Bolton: And 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 want to take your sensitive electronics
Of your spacecraft through that environment --
At least not for long.
Bolton: We had to somehow get beneath the radiation belt
If we can just thread that needle...
I was just praying with my eyes closed,
You know, 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.
Bagenal: Fly the engines.
Woman: Good now?
Yeah, we see that the engine has started.
35 minutes, they're firing away,
Slowing down the spacecraft,
So it gets caught in jupiter's gravity.
Woman: Juno, welcome to jupiter.
[ cheering ]
Nasa did it again.
♪♪
Bolton: And 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 go
Run through that fire with our bare feet.
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, is just extraordinary.
Little did we know that the poles of jupiter,
We're gonna become this huge science discovery by itself --
Giant polar cyclones.
Nobody anticipated that.
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.
And 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.
So, 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.
Arnou: 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.
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 at the top.
Bolton: There's probably something deep down
That is driving a lot of motion inside of jupiter.
Bagenal: And so, we're beginning to think about that region
Where hydrogen becomes metallic,
That generates this strong magnetic field.
Bolton: 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 loose.
Arnou: 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 at the top.
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.
Bolton: 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. Right? And browns.
And io is spewing out tons of sulfur,
Among other things, because it's volcanic.
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.
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.
It may be that we've been a bit naive,
That if jupiter could throw us this many curveballs,
That our ideas of how stars work 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.
And jupiter is 1000th the volume,
And 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.
♪♪
Narrator: Juno continues to explore jupiter,
Diving beneath the lethal radiation belts
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 subsurface ocean?
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.
Juice doesn't launch till 2022.
It's not gonna get there until 2030.
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.
Klesh: 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.
Well, the first challenge you have is actually
Getting down through the ice.
And while people have talked about drills,
And other such things,
We want to 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, theses 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, drives on the underside of the ice
Exactly at that ice-water boundary on there.
And by turning a camera to look up at the microbes
That we might find there on the underside of the ice.
And 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.
In the mid 2020s,
We hope to launch europa clipper.
Then, after a six to seven year voyage,
Will reach jupiter itself.
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.
And the rovers that we're developing,
And testing here on earth,
Are only the ancestors --
The far ancestors of what we might eventually send there.
Narrator: So, perhaps one day, we will 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.