["Johnny B. Goode" by Chuck Berry playing]
[beeping]
♪ Deep down in Louisiana Close to New Orleans ♪
♪ Way back up in the woods Among the evergreens ♪
♪ There stood a log cabin Made of earth and wood ♪
♪ Where lived a country boy Named Johnny B. Goode... ♪
[boy] Hello from the children of planet Earth.
[man] ...extend the greetings of the government and the people of Canada
to the extraterrestrial inhabitants of outer space...
[woman speaking in foreign language]
[Carl] From my point of view, the search for extraterrestrial life,
and especially the search for extraterrestrial intelligence,
is one of the key philosophical, scientific and human questions
that have been posed, but we are at the very beginning of searching.
[people speaking in multiple languages]
[narrator] It was Carl Sagan's idea
to send a greeting card to our neighbors in the cosmos.
An idea ahead of its time,
since we haven't really met any neighbors out there
in the vastness of space.
We still haven't, but we're getting closer every day.
[thunder crashing]
[insects chirping]
It was a greeting not only in words and images,
but full of the sights and sounds of our precious planet.
[heart beating]
[children laughing]
[baby crying]
[narrator] It's a message in a bottle
that we sent into the sea of interstellar space,
where it's still sailing
at 11 miles per second towards the unknown.
[animal howling]
[instrumental music playing]
[narrator] Sagan said that, "We make our world significant
by the courage of our questions,
and by the depth of our answers."
He wasn't afraid of making extraordinary claims,
as long as they were backed up by extraordinary evidence.
It might be a while before we hear
from an alien who's found our message in a bottle.
So today, instead of waiting to hear from life out there,
we're going to go looking for it.
Let's start here,
on the top of Mauna Kea in Hawaii,
where the W. M. Keck Observatory scans the clear night sky.
Carl Sagan knew what explorers have always known,
by understanding more about our neighbors,
we will understand more about ourselves
and our place in the universe.
No one knows Sagan's vision more than Lisa Kaltenegger,
the director of the Carl Sagan Institute at Cornell University.
[Lisa] Carl Sagan and his approach to science inspired me.
We are using many different fields of science,
astronomy, chemistry, biology, engineering and many more,
to make a forensic toolkit
to understand our place in this fascinating universe.
[beeping]
[narrator] Before the Voyager spacecraft left our solar system,
it made some remarkable discoveries.
It proved that we need to be more open-minded
about where we search for alien life.
In 1980, Voyager first reached Saturn...
a raging ball of hydrogen and helium storms.
Not much chance of finding life there.
Voyager then turned to one of Saturn's 62 moons...
capturing the first close-up images
of Saturn's largest moon, Titan.
What it saw stunned astronomers.
Titan had a dense atmosphere, mostly made of nitrogen.
Twenty-four years later, the Cassini probe revealed even more.
On the surface are vast lakes of hydrocarbons,
the building blocks of amino acids, proteins.
Cassini continued on its celestial road trip,
where it found this frozen outpost, Enceladus.
This moon appeared to be frozen solid,
a dead ball of ice,
until something astounding was spotted near the south pole...
huge plumes of water,
spouting through cracks in the surface ice.
Beneath the frozen surface of Enceladus, was an ocean of liquid water.
It turns out that planet Earth
doesn't have a monopoly on water like we once thought.
[Lisa] On Earth, water is key to life.
It abounds on our planet and every animal, every plant,
every life-form depends on it for survival.
The seas are where life was born.
Water is the lifeblood of existence.
On Earth, liquid water is critical for life-forms that live in it...
as it is for those that live out of it.
When we search for alien worlds that might support life,
the presence of liquid water is a critical clue.
If a world has liquid water, there's a chance for life.
[narrator] First discovered by Polynesian seafarers,
Hawaii is one of the most isolated string of islands in the Pacific.
These islands were formed when magma bubbled up
and cooled into mountains.
Each new outcropping of lava
is home to a dazzling variety of plants and animals, from above...
and below the surface of the sea.
More than 25,000 species
make this one of the most dynamic living habitats anywhere.
A living laboratory for the resilience of life.
[Lisa] Biologist Chris Johns
knows the fauna and flora of Hawaii really well,
including some amazing examples of the extremes
life will go to, to survive.
[narrator] A stretch of barren lava rock.
It isn't the first place you'd expect to find life...
but that's exactly where nature has hidden a few surprises.
[steam hissing]
[Lisa] These lava tubes extend for miles.
They were created when lava drained out from an ancient volcanic eruption
beneath a crust that hardened above.
This is amazing, a whole new Hawaii I've never seen before.
A secret, hidden Hawaii.
[Chris] Keep to your left.
It's just up ahead.
[narrator] In this upside-down place,
you have to look up to see the roots of the remarkable Ohia tree.
[Lisa] They're beautiful,
hanging down into the caves like sparkling jewels.
Yeah, so we can actually check out some of these microstructures...
And they sparkle
because they're covered in water,
moisture that has condensed from the humid air.
Life needs liquid water to survive,
but the Ohia tree shows us that it can be very innovative
in the way it finds it.
-...for our data collection. -OK.
[instrumental music playing]
[narrator] This is the Haleakala Valley on the island of Maui.
NASA uses alien landscapes like these to test their Mars rovers
before sending them off to the Red Planet.
The soil here is made of cinders,
the altitude is over a mile high
and the weather is dry, sunny,
windy and freezing.
It's the last place you'd expect Mother Nature to start gardening.
This is the Haleakala silversword.
Its fat leaves store water and are covered with tiny hairs
that pick up humidity in the dry air
and send it down as liquid water to the roots.
Water, as liquid, or carried on the wind,
or coursing across the landscape,
makes Earth a thriving paradise of life.
Water, with a dash of carbon
and a little energy from the sun,
are the simple ingredients for life to blossom.
[indistinct radio chatter]
[narrator] In the canyons of this undersea world,
there is no sunlight and the water pressure is,
to put it simply, bone-crushing.
And yet, more than a mile down from the surface,
life flourishes.
These hydrothermal vents leak out heat and minerals
from the Earth's core.
They're called black smokers and ooze clouds of sulfur,
which is toxic and smelly to you and me,
but to the deep-sea bacteria that thrive here,
it's good, wholesome nutrition.
If life can thrive here in the dark, pressurized depths of Earth's oceans,
what about other oceans,
like the one on Enceladus?
[Lisa] For years, we have searched the planets
in our solar system for signs of alien life.
But perhaps it will be a moon that first confirms that we are not alone.
Some moons have all the key ingredients for life,
water, carbon and energy.
Energy not from the sun or from volcanoes,
but from massive tides, crammed beneath the icy crusts
and dragged around by Saturn's colossal gravitation.
[narrator] Next stop, the moons of the gas giant, Jupiter.
Ganymede,
the largest moon in the solar system.
This big guy is covered with an icy crust
which hides an astonishing surprise...
perhaps more salt water than all of the oceans on Earth combined.
And what's waiting for us here on the surface of our neighbor, Mars?
These are actual images
captured by the Mars Reconnaissance Orbiter
that shows the Red Planet covered in topsoil.
When the NASA rover, Curiosity,
first scooped up a handful of this red soil.
Geologists thought it looked surprisingly familiar,
like the soil back home in Hawaii.
Mars has water, masses of it,
frozen at the poles and more buried within its soil.
Water, carbon, energy from the sun,
all the basic ingredients for life are here.
That's why biologists
wouldn't be surprised to find life on Mars,
not the kind with flying saucers and ray guns,
but still, fascinating microscopic and very real life.
[Lisa] They would have to be resilient,
able to withstand extreme temperatures
and a constant bombardment by radiation from space.
Our own planet has a magnetic field and a thick atmosphere
that largely shields us from deadly cosmic radiation.
[narrator] When we humans make it to Mars,
we'll need a lot of technology just to help us survive.
But there are some residents of Earth
that would thrive on the Red Planet.
The water bear or tardigrade is a perfect example
of extreme survivalist,
a tiny, water Bear Grylls.
[indistinct radio transmission]
[narrator] In the toughest test of all, these hearty little guys
were launched into the frozen vacuum of outer space
and blasted with severe cosmic radiation...
[indistinct radio transmission]
...hostile to humans, but not to water bears.
I am constantly reminded of the tenacity of life.
Perhaps life in our solar system is far more common than we realize.
In 2022, an ESA spacecraft will take a closer look
at Jupiter's moon, Europa, and its mysterious red cracks.
Ice-penetrating radar will show us what lies beneath the surface
of this strangely scarred world.
[narrator] Astrobiologists constantly scour space
for the conditions that support life.
And their search doesn't end in our own backyard.
It's beyond our solar system
that the really exciting discoveries are waiting.
These are "The Pillars of Creation,"
massive clouds of gas and dust.
This cloud of dust is a star factory in our own galaxy, the Milky Way.
It's in awe-inspiring places like this
where nature churns out billions and billions of stars.
And around many of those stars, planets,
perhaps as many as one hundred billion...
and on those planets... possibilities.
[Lisa] Some of the planets we have already found are much older than Earth,
worlds more than twice the age of Earth.
If such planets have life,
it could have evolved much further than us.
[radio blips trilling]
This is the Kepler telescope,
a remarkable planet hunter that has already discovered
more than half the known planets beyond our solar system.
But how?
[indistinct radio transmission]
[Lisa] With extraordinary sensitivity, Kepler is able to lock onto distant stars
to detect if something passes in front of them,
tiny dots that dim the star's light ever so slightly.
Tiny dots equal planets.
Only a month into operation, Kepler found its first giant planets,
all bigger than Jupiter.
Slowly but surely, even though they are much harder to find,
Kepler has discovered more and more small planets
and among those, the first potentially Earth-like worlds.
The other amazing thing is that Kepler has found
all these planets by searching only a tiny piece of the galaxy.
Until recently, Kepler was always focused on exactly the same area of the Milky Way,
spanning only two percent of the night sky.
And in this tiny area, it has detected thousands of planets orbiting alien suns.
I think this would have been one of Carl Sagan's dreams coming true.
[narrator] Once Kepler has found evidence of a new planet,
the data is turned over to astronomers back here in Hawaii.
Giant telescopes can confirm Kepler's findings.
Once confirmation has been made,
telescopes can go further and actually observe distant planets.
More than 120 light-years away,
this small red dot is the very first alien planet
ever seen by humans.
It's nearly 13 times the mass of Jupiter
and orbits around its own parent star.
More and more of these distant planets are coming into focus.
As our telescopes become smarter and more powerful,
we might even spot a planet with a tiny halo,
an atmosphere,
and just maybe a thriving habitat for life.
Lisa knows the procedure very well.
In fact, she's writing the rule book on it.
[Lisa] When light filters through a planet's atmosphere,
it creates a spectral fingerprint,
telling us if the planet possesses the essentials for life.
[narrator] We're living in a new golden age of space exploration.
Over a dozen spacecraft have already been dispatched to Mars.
If there's life there, we'll find it.
The conditions for life are everywhere you look in the universe
and as our ability to see improves,
so does our ability to discover and learn.
The Messenger probe took a trip to Mercury
where it found frozen water on the surface.
The Juno spacecraft flew half a billion miles to orbit Jupiter,
where it's unwrapping the mysteries of the gas giant,
which may actually have a solid core
hidden beneath the storms raging across its surface.
And as an encore, we've landed a spacecraft on a comet
as it flew through our neighborhood on its long journey around the sun.
And there we found something astounding
and essential to human life, oxygen.
And finally, scientists have now discovered
an Earth-like planet in our neighboring solar system.
We call it Proxima b.
It doesn't get any closer to home.
[Lisa] Imagine that soon we could discover continents, oceans
and maybe the first sign of life on alien worlds.
This is what Carl Sagan implored us to do.
[narrator] Human endeavor and curiosity are helping us better understand
our purpose in the universe.
When we leave Earth's grasp and venture into space,
we stand as one,
representing all of humanity.
Life out there might be microscopic or it might be someone intelligent enough
to find Voyager
and listen to our message in a bottle.
[child laughing]
[boy] Hello from the children of Planet Earth.
[man] ...extend the greetings of the government and the people of Canada
to the extraterrestrial inhabitants of outer space...
[people speaking in multiple languages]
[instrumental music playing]