For more than a decade, I've made programmes about the universe...
and our place within it.
There it is! There it is!
I can see the parachutes.
I've had some remarkable encounters...
I can't believe you can just stand next to a spacecraft...
Release...
memorable experiences...
They came down exactly the same. Wow!
and explained some beautiful science
about how our planet works.
That really is the thin blue line that protects us.
Look at that!
Now, I'm taking a new look at those past programmes.
This surely is as close as I'm going to get to being in space.
I think our knowledge really has moved on since we made these films,
so it's really interesting
to revisit some fundamental questions again.
Are we alone in the universe?
What really is gravity?
Where will the exploration of space take us?
TICKING
And what is time?
BEEPING
Beeping is never good.
I've come to the Royal Institution...
the historic home of science,
to watch some my old films.
I'm starting by looking at a question
that's fascinated me since I was young.
How far can we go in our exploration of the cosmos?
The way you acquire reliable knowledge about nature,
about the universe beyond Earth, is to go and look, to explore.
I think now we're living through the beginnings of a new age
of exploration.
Physical exploration of the universe beyond our planet.
At this point in the 21st century,
for the first time,
space flight is on the verge of becoming routine.
And I do really think that with the advent of, particularly,
reusable rockets that fly up into space,
deliver something into near Earth orbit,
and then come back down again,
we're on the verge of a golden age.
How far can we go?
I was always interested in space when I was growing up.
The first thing I really remember was the first flight
of the space shuttle, which actually, as I speak now,
was 40 years ago yesterday.
And I remember that absolutely vividly.
These things that I saw on television growing up,
you know, astronauts training underwater,
or flying in jet fighters...
I never thought I would get the chance to do any of those.
I am floating in a spacesuit above
the International Space Station.
It's surely as close as I'm going to get to being in space.
Astronauts have to do this for hours at a time, six, seven,
eight hour space walks, they're going to have to perform
many of them to install this module when it's taken up into space.
Over there, that's the Zvezda module,
the Russian habitation module where the cosmonauts sleep,
you know, where they eat - it's their lounge in space.
You can just imagine, can't you?
If you imagine the Earth stretching out over there, curving away.
Ahh...
I think it'd be wonderful - so wonderful.
It's kind of one of those things you always dream of, you know?
I did, anyway - doing a space walk
out in space on the Space Station.
This is undoubtedly the most physically demanding thing
I've ever done.
What I learnt, ultimately, is that I don't have the right stuff,
I have the wrong stuff - cos it's really hard!
Since November 2nd, 2000, when the first expedition arrived,
the International Space Station has been continuously occupied.
HE SPEAKS RUSSIAN
Humanity's permanent outpost amongst the stars.
You know, for me this defines what it means to be human.
Throughout the whole history of life on Earth,
of all the creatures that have ever lived in the oceans
and the land or in the sky,
only one has ever made it off its home world.
So, why is it that we alone have ventured out into space?
What is it that makes us special?
Exploration is important.
It's the way that we acquire new knowledge about the world around us.
We're part of this world.
And if you think about the world
not only as the surface of our planet, but the wider environment,
there's a great deal more territory to explore beyond the Earth
than there is on the surface of the Earth.
The International Space Station is the current frontier
for humans in space.
For the last 20 years now, there has not been one second
when all humans have been confined to their home world.
The space station has been continuously crewed
for all that time.
It's a tremendous achievement.
And what we've learned is how to live and work
and build beyond our planet -
that's the great gift of the International Space Station.
But exploration doesn't have to be physical.
We tend to think of exploration as walking across new terrain
and planting a flag like the polar explorers of old.
But it doesn't have to be that. It can also be intellectual.
And actually, for most of history,
our exploration of the universe beyond Earth has not been physical,
it's been looking up at the stars.
These are the Atlas mountains in North Africa.
According to Roman legend, they held the heavens above the Earth.
And they are one of the finest places to come to view the stars.
From a place like this, it's easy to appreciate the profound effect
that the night sky would have had on our ancestors.
You know, from a modern perspective,
astronomy can seem remote and arcane,
because we've lost our connection with the night sky.
From a city, you just don't see
a sky look anything like this.
From the darkness of the Atlas mountains,
it's really truly majestic.
So, f0!' OUT BHCGStOFS,
the connection with the night sky would have been incredibly intimate.
They looked into the skies to understand their place in creation,
and the movement of the stars told them one thing.
They were at the centre of the universe.
Up there is Polaris, the North Star,
and it's almost exactly aligned with the Earth's spin axis,
which means that as the Earth rotates,
all the stars rotate through the sky around that point.
So, it looks for all the world as if the Earth
is at the centre of the universe
and the stars rotate around it.
Of course, that's what the ancients thought for thousands of years,
and why not? Because it's obvious...
but wrong.
To understand the Earth's real position in the solar system,
we need to look at the one set of bodies that doesn't behave
as predictably as the stars.
The Greeks named them "planetes", or wandering stars,
and we have kept the name planet to describe them.
This is Mars, photographed once a week over a period of months.
Rather than travelling in a straight line across the background of
the stars, it occasionally changes direction and loops back on itself.
It's very hard to explain these retrograde loops
if the Earth is at the centre of the universe.
Understanding the retrograde motion of Mars didn't come easy.
That's why it took over 2,000 years to work out,
but I'm going to explain it using a stick and some rocks.
The key thing is that the Earth
is not at the centre of the solar system.
The sun is.
And the Earth and Mars go around it
in almost circular orbits.
So, when Mars is viewed from the Earth,
then it's seen on the sky.
In fact, on the constellations of the Zodiac.
So, as Mars orbits around and the Earth orbits around,
then from that position, Mars will look like it's there on the sky.
Mars moves and the Earth moves in that position,
and Mars moves in that direction across the sky,
and again, in that position, Mars will be here.
So, you see, it's moving in a straight line across the sky.
But what happens when the Earth overtakes Mars?
Then, look at the line of sight.
Mars has moved back to there.
It's reversed its direction.
And it continues to do that until the Earth
gets round to somewhere like there
and Mars is here, and then you see
the line of sight means that it's started moving that way again.
So Mars has executed that strange looping motion on the sky
because the Earth overtook Mars
on the inside,
and that's why the retrograde motion happens.
Simple!
Understanding the retrograde loops was one of the major
achievements of early astronomy.
It created the concept of the solar system and allowed us to build
the first accurate maps of the planets
and their orbits around the sun.
You might say, well,
how ridiculous is it to think that we are the centre of the universe?
But Aristotle had a good argument for that.
He said, "Well, the Earth is at the centre of the universe
"because everything falls towards it, and it's not moving."
That's actually what we observe.
It's a really terrific intellectual leap to realise
that, actually, you're on a little ball of rock
careering around a star,
which is itself careering around the centre of a galaxy,
which is itself careering through the universe
with trillions of other galaxies.
None of that is obvious.
All of it requires exploration and thought.
As we continued to explore,
we learned just how vast the universe is.
The biggest breakthroughs have happened in the last hundred years.
I think it really was a remarkable time in the first half
of the 20th century, because in parallel with the developments
in cosmology, where we're learning for the first time, really,
that we live in a vast universe -
we're also developing the technology to explore it physically.
When you think about the rate of achievement, you know -
at the turn of the 20th century, no powered flight existed.
Nobody had ever left the surface of the Earth in anything
other than a balloon.
Technology broadened our horizons.
INTENSE BLAST
And a new breed of explorer was born.
In the world of space exploration,
this room is hallowed ground,
because every astronaut
that flies to the International Space Station today, and indeed
pretty much every astronaut that's ever flown into space,
first American, then Russian and European,
have sat at this table and signed this book.
This is so precious.
It's a tradition that began in 1969
with three Soyuz crews,
Soyuz-6, 7 and 8.
As you flick through the pages you just turn through
the history of space exploration.
And here on a visit, June 1st, 1970, is Neil Armstrong.
The reason every astronaut wants to come here and sit at this table
is because this table,
and all the furniture in the office,
everything you see in the office,
belonged to Yuri Gagarin.
This is a great speech.
An unprecedented duel with nature -
could anyone dream of anything greater than that?
You know, it's easy to characterise the early astronauts,
the pioneering test pilot astronauts, as emotionless people.
You know, people who were just interested in flying the vehicles.
But you only need to listen to Yuri Gagarin's words to realise that
he knew precisely the significance of what he was about to do.
On April 12th, 1961,
we became a space-faring civilisation.
Just being immersed for a few clays in the Russian space programme,
there's an almost spiritual motivation -
you can see it in the art.
Alexei Leonov, the famous Soviet cosmonaut,
did these beautiful paintings...
which I think had a sense of that - it's almost like
it's our destiny to return to the stars.
For me, we,
by which I mean the human race,
are at our best when we over-achieve,
when we do something
that really, we weren't quite capable of doing at the time.
And the Apollo moon landings have to fall into that category.
The fact that you can navigate a quarter of a million miles
through space and land on the surface of the moon
and then take off from the surface of the moon,
re-enter the Earth's atmosphere,
with all the tremendous engineering challenges that that entails -
aerospace, in my view, was not really ready to do that.
I think it's just a beautiful example of engineering overreach.
This most extraordinary quest to put a man on the moon
required the most extraordinary rocket.
The thing about the Saturn V is it's just enormous by any standards.
And the challenge was, how do you film that?
You can just about,
if you go a long way away with a big wide lens,
fit it in shot.
But that doesn't tell you anything about the scale of this thing.
And you realise that it takes you
about two or three minutes to walk along it,
and so we thought, "Well, let's do that, then."
But of course, if you want to do that, then you can't cut.
You've got to have one shot that tells you the scale of this thing.
This is the spacecraft that took John Young, Ken Mattingly
and Charlie Duke to the moon.
There's the service module and the command module,
that's the engine that fired to bring them
back from the moon to the Earth.
The lunar lander sat inside there
and this piece is essentially a single rocket motor
that fired to take them from Earth orbit to the moon.
So, this is the 120 tonne moon spacecraft, if you like.
But from a physics perspective, the difficulty is getting
that into orbit.
On Saturn V, that was done in two bits.
This is Stage Two
and that is the Stage Two fuel tank.
Inside there are 450 tonnes of rocket fuel
and this burnt through those 450 tonnes in about six minutes,
taking the spacecraft from an altitude of 200,000 feet,
about 38 miles, up to 114.5 miles,
that's virtually in orbit.
It did that by burning the fuel in five engines.
Now, at the time,
that was one of the most powerful rockets ever built,
but not the most powerful.
That was this -
Stage One of the Saturn V.
There are 2,200 tonnes of fuel in here
and Stage One burnt through that in about two and half minutes.
To do that, they had fuel pumps that were more powerful than a 747
at lift off to pump 15 tonnes of fuel a second
into these...
The F1 engines.
Every statistic about these engines is ridiculous.
In those two and half minutes,
when this spacecraft was lifting off,
the power generated was more
than the peak electrical generation capacity of the United Kingdom.
It's one of my favourite shots that I've ever been involved in
because it was so, so difficult.
Hi. Charlie.
One of the great honours I've had whilst filming is to meet
some of the astronauts who've travelled to the moon.
Hello, Charlie.
Nice to meet you, good to see you. Wonderful to meet you.
Good to be here with you. Have a seat.
Charlie Duke was a lunar module pilot for Apollo 16
and the youngest person ever to walk on the moon.
We're feeling good.
Mission objective, to bring back samples from the lunar highlands
and test drive new technologies.
Here we go.
We're really going up a hill, I tell you.
When I was just becoming aware of Apollo,
I thought that I would be able to go into...
at least into Earth orbit myself.
Yeah, really. My dad was born in 1907
and so he was just right after the Wright brothers
and he could barely believe that his son went to the moon.
And yet at the time, my five-year-old, Tom,
he didn't think it was any big deal, you know,
that everybody in the neighbourhood was going to the moon.
Bill Armstrong was a next door neighbour,
Tom Stafford was in the neighbourhood,
Frank Borman was in the neighbourhood,
the whole neighbourhood was either NASA engineers or astronauts,
so for everybody, it's natural,
"Let's go to the moon, Dad, when are you going to do it?"
Hey, this is perfect, with the rover and you
and the mountains,
and the old flag.
Come on out here and give me a salute.
Big Navy salute.
Off the ground a bit more.
There we go.
I mean, you're most famous, probably, for the most famous
photograph involving you and it's not you -
it's the photograph of your family that you left on the moon.
Yeah, I asked the boys, they were five and seven,
I said, "Would you guys like to be with your dad on the moon?"
They said, "Oh, yeah, that'd be great, Dad."
So on the back of that picture we had written,
"This is the family of astronaut Charlie Duke,
"from planet Earth, who landed on the moon in April 1972."
We all signed it
and then I dropped the picture on the moon.
It sort of shows the human side of space flight and, you know,
we were family men, we were dads, husbands,
and so wanted my family to be a part of it.
They'll sit there for millions of years, those, won't they?
They won't go anywhere.
If you look back to those clays, so, less than a year from first
test flight, first manned test flight to landing on the moon.
Yeah. Would that be possible now? No.
Why? We don't have the schedule,
the money, to build spacecraft that quickly.
We don't have the, er...
manpower to do it.
I mean, 400,000 people and unlimited budget, you can do a lot.
Yeah. And so that's...
That's what we had.
After Charlie left, only two men have ever gone back.
At the end of Apollo, early 1970s,
I think most people thought that we would be back to the moon
quite soon.
Actually, it's been 50 years and we haven't gone back.
But now we're trying to re-acquire those skills
because we want to go further.
So, the next step is Mars.
Mars is in our back yard.
It's the most Earth-like place in the solar system,
other than the Earth, but by a long way -
it's almost habitable.
So, I think if there is going to be a new frontier physically,
that we're going to explore,
then there is no choice - it has to be Mars.
I think the difference between the future Mars missions
and the Apollo missions is that Apollo was a national endeavour.
Mars won't be like that.
Now, the visionaries,
the people who are really trying to excite us
and push us out towards the stars, to Mars and beyond,
are not only focusing their efforts on national governments,
they're also focusing on developing the expertise in the private sector.
Foremost amongst those visionaries
is aerospace engineer Dr Robert Zubrin.
He's a legend in space geek circles
cos he wrote the books on how to build a space-faring civilisation,
how to colonise Mars.
Er, OK.
So, here's my lab.
This machine here is one of the most important.
This is for making rocket fuel and oxygen on Mars,
out of the Martian atmosphere.
Since the 1990s, Zubrin's proposal of a lightweight,
"live off the land" approach to visiting Mars has influenced many,
including NASA.
So, this is really a lab, aimed at ultimately colonising
and building bases,
creating resources out of raw material, and staying there.
Yes.
This is...
my invention for cleaning clothes in space.
I call it the "vacuum cleaner".
It sucks out all the air.
It boils off all the water and all the oils.
It explodes all the bacteria.
They're dead.
The stuff is clean.
Some of Zubrin's ideas may seem unconventional.
But it's his back-to-basics approach that has proved so appealing.
Can you give us some indication of the difficulty of humans
going to Mars and then colonising?
Cos you've got these wonderful paintings on the wall.
This is a depiction of my mission plan for human exploration
to Mars, which is known as the "Mars direct plan".
There's nothing in this that's fundamentally beyond our technology.
We're not talking about venturing into new
and unknown worlds of physics here.
We're talking about brass tacks engineering.
Building systems of moderate size,
flying them to Mars.
We do not need giant Battlestar Galactica spaceships.
How optimistic are you that this is something different now,
in 2017, to the way the world was in, let's say, the year 2000?
In the year 2000, we knew about people like Elon Musk.
They were characters in science fiction stories,
of the entrepreneur who would come along and make this happen.
Well, now those characters have stepped out
of science fiction novels,
and they are now in the real world, doing this stuff.
Zubrin's zeal for finding a way to reach Mars
is driven by a belief that it is the only option humanity has
to ensure its long term survival.
The worst idea that anybody has ever had
is that there is only so much to go around, OK?
And that therefore, nations are all enemies of each other.
If we can get off this rock
and see that the world we live in is not this planet -
this is not the world, this is just one planet
in a world of trillions of planets -
and that there are unlimited resources available to us
if we maximise the reach of human creativity.
And therefore, every nation is fundamentally
the friend of every nation, and every person of every other person.
Zubrin has a view which I share, actually.
Which sounds ridiculous when you first vocalise it.
How do we grow our civilisation without destroying our planet,
without destroying ourselves?
He takes it as read that we have to expand.
I don't see that our future,
for the indefinite future,
can be just based on being more and more careful
with dwindling resources here on Earth
when, as Zubrin points out,
there are unlimited resources available beyond Earth.
I think, inexorably, the logic leads up there.
Zubrin's ideas have influenced a new kind of space explorer.
Billionaires, like Elon Musk and Jeff Bezos,
are building rockets.
They see Mars as the next great frontier
and space exploration as the saviour of our civilisation.
I remember speaking to Jeff Bezos, which was a real privilege.
So, he says he wants to zone the Earth residential.
That sounds ridiculous, doesn't it? "What are you talking about?"
But, of course, if you have a paradise island
in the middle of the Pacific Ocean,
you don't decide to build a steel mill on it. Right?
Well, the Paradise Island is the Earth.
And so, where should the steel mills be? We need them.
Ultimately, the vision is to have the dirty heavy industry stuff
up there, where all the resources and all the energy are,
and keep this place pristine.
Steel mills on Mars might sound like science fiction,
but NASA is developing machines for mining and building on other worlds.
The moon is seen as a stepping stone to Mars.
One day, robots will mine the lunar surface
to build habitats for human settlers.
One stick drives one side of the wheels
and the other stick drives the other side of the wheels.
Robotics engineer Aj Nick is letting me take one out for a spin.
So, we can turn on this button.
You can go ahead and raise this arm over here, and keep driving.
There is a real feeling of stability there, and...
Ha-ha-ha!
You're confident I can't break this?
I have done way worse to this robot.
I suppose the obvious question is, if you want to mine this,
why don't we just get a shovel and dig it up?
Why is the robot so complicated?
The first problem is, we're trying to make
everything as lightweight as possible, to fit inside of a rocket.
And then you get there on the lunar surface,
and you have reduced gravity once you get there.
So, now the thing that was already really light,
because you had to make it light to fit in the rocket,
is even lighter while it's there on Earth.
This is really some rock. Really shocked.
With one sixth of Earth's gravity,
operating on the moon creates a challenge.
I'm going to explore right here.
While the Apollo astronauts could move around with ease,
they found simple tasks like digging and collecting rocks difficult.
Argh!
Current Earth terrestrial excavators actually get their
excavation force, their ability to cut through the soil,
from the weight of their vehicle.
Here, since we don't have a lot of weight, it's very difficult.
Aj and his team have come up with a unique design,
that will allow their robots to work in the moon's weak gravity.
So, now I'm digging.
The scooping drums at either end rotate in opposite directions.
This has the effect of pinning the robot to the ground,
allowing it to dig without floating off into space.
As one drum on the front is digging, the other drum is rotating
in the opposite direction from the other drum.
And so, that allows the excavation forces to be cancelled
as it's digging.
This is the only vehicle in the world that can dig
more than its own weight.
If I took it into this trench the wrong way, it may well fall over.
Can I do that? Yep.
Oop!
Unlike other planetary rovers,
these robots are meant to be robust,
designed to get themselves out of problems,
even if they're flipped upside down.
It's really easy to drive, and really manoeuvrable,
and really powerful.
It does seem like you can get out of a lot of trouble.
Once the lunar dirt has been dug up,
it needs to be transformed into a building material.
I'll show you some materials here.
Senior technologist Robert Muller has been sintering the lunar dust,
heating it until it solidifies.
So, the result, a well sintered regolith, is this.
And that's essentially turning crushed rock back into solid rock.
That's really quite heavy actually, that feels quite dense.
So, that is just this material in an oven, essentially.
That's right.
By mixing the regolith with plastic,
Rob can create something far more versatile,
a material which can be used in a 3D printer.
And we use the big robot arm, we have a print head on it,
and then we are able to make objects like this.
This is a blast deflection wall.
This is an ogive dome.
It could be used for the roof of a habitat when it gets really big.
And in fact, it's quite strong.
If you look down at it, it's very strong.
You can kick it all day long and it won't break. That's quite...
So, that is built by that robot?
Yes.
Using, essentially, the regolith that you would find on the moon?
That's correct.
So you never bring any materials from Earth.
You go mine them on the moon, and then you build whatever you need
to create your local moonbase out of local materials.
All you have to bring is the robot.
Everything is there, is the point?
Everything is there,
the only two things missing are technologies and imagination.
If we can put those two things together,
and harness the materials and the energy we have in space,
we have all the resources in space we need.
We just need to be clever enough to learn how to use them.
The plan is to use the moon to learn how to colonise Mars.
So, landing on and then, in the future,
colonising Mars is tremendously exciting but,
and it seems ridiculous to say it,
but it's worth reminding ourselves,
there are going to be tremendous challenges.
Get it!
These are the dunes in the Namib Desert.
It's an absolutely spectacular place.
This place is not the hottest or the driest desert in the world,
but these dunes are some of the oldest sand dunes in the world.
And the reason we're here in the Namib Desert is that this is
a great analogue for the surface of Mars.
This is what the surface of Mars looks like,
and these dunes, called barchan dunes,
these crescent shaped dunes,
are the same as the sand dunes on Mars.
So, if you want to get a feel for what it would be like
on the surface of Mars,
and you want to know what driving a 4x4 around on it would be like,
then this is the place to come.
Mars has vast dunes...
"GHOFITIOUS VOICGHOGS...
and giant ice sheets.
It has canyons and river valleys.
Mars is a dry, frozen version of our home,
covered in red dust and sand,
and it's all due to the fact that Mars has virtually no atmosphere.
Mars is not a nice place.
You have problems with radiation, you know,
very limited magnetic field, virtually no magnetic field,
so very little protection from solar radiation.
It's cold and it's barren and it's arid.
The problem with humans is that they're quite fragile things
and we need a big infrastructure,
a life support system to colonise Mars.
And that's really difficult.
It is at the limits of our current technology.
So, if we want to explore the universe beyond Earth...
it is simpler to do it with robot explorers.
Sending robotic probes in our place has allowed us
to explore deeper into the cosmos than we could ever go.
TYRES SCREECH
CAR HORNS BEEP
In the last 50 years, we've sent unmanned space craft to every
corner of the solar system.
No, no, no, no!
HORNS BEEPING Tram!
Many not much bigger and not much more advanced than this car.
Whoops, sorry.
So this is the most dangerous thing I've ever done.
I've flown in jet fighters,
I've dived to the bottom of the ocean,
I've been astronaut training in Russia, zero G flights,
but nothing was as dangerous as driving a vintage Fiat 500
around Rome in rush hour.
It's a beautiful piece of engineering
but it's essentially got no brakes.
We sent Mariner 10 and Messenger to Mercury,
the closest planet to the sun.
It's got no acceleration.
I don't know what these sticks do here.
43 missions to Venus...
and 51 to Mars...
AGGRESSIVE HORN BEEPING Wa-hey!
but only a handful have made it
into the solar system's outermost reaches.
In 1977, a chance alignment of the planets meant that it was possible,
at least in principle, to launch a spacecraft to all four
of the outer gas giants,
so NASA launched two spacecraft - Voyagers 1 and 2.
Just 18 months later they reached the largest planet
in the solar system, aptly named after the Roman king of the gods,
Jupiter.
They explored Saturn...
before separating, with Voyager 2 going on to visit Uranus.
And then in 1989,
after travelling for 12 years...
it reached Neptune -
the most distant planet in the solar system.
When I was growing up I had this book, which is a book
into which you stuck cards
that you collected in packets of tea, right,
and this particular book is The Race into Space.
And I loved this.
You can see how long it was ago cos it was 5p.
This is in the early 1970s.
Right at the end, one of the future missions is the grand tour
of the solar system, because it was known that
if you launched a spacecraft in the late 1970s,
there is a chance planetary alignment
which means that you could send a single spacecraft
to Jupiter and Saturn and then to Uranus and then to Neptune.
And this became the Voyager programme,
Voyager 1 and Voyager 2.
Voyager 1 is the furthest artefact of our civilisation.
Right out there.
Twenty two thousand million kilometres away!
It's been in space for over 40 years.
It's almost incomprehensible,
and it's even more incomprehensible that we're still in contact with it.
And in my favourite book,
from when I was growing up,
there's a picture - the Goldstone Mars station.
And so, it was almost like the fulfilment of a childhood dream
seeing it on the horizon.
I had this book with me.
I got it out and looked and went, "Yep, there it is."
Today, the Goldstone Station is listening out for the faintest
whisper from Voyager 1.
Call 233.
It's almost there now
so we should be seeing it coming in.
Voyager is so far away
that it takes the signal around 15 hours to arrive,
travelling at the speed of light.
Now we've got the receiver.
Oh, that triangle?
Yeah, that's it, right there. There it goes.
Yeah, yeah.
It may appear as little more than a blip on a screen but, for me,
it's beautiful.
I mean, you just have to think about it, this little thing,
it's no bigger than a double decker bus,
designed in the late '60s,
launched in the mid '70s,
and still functioning 32 years later.
Good science data is still coming out of that little spacecraft.
I think it's absolutely wonderful.
This was a wonderful thing because it was real.
And after all those years that I'd followed this spacecraft,
you can see, right, in my face,
just absolutely,
completely forgot that I was making a television programme.
And just got carried away by the moment.
Just wonderful.
Voyager1 is now in interstellar space,
14 billion miles from Earth.
After photographing the outer planets of our solar system,
Voyager took this image.
Known as the pale blue dot,
it's the most distant image of our home planet ever taken.
Earth as a single pixel.
And after more than 40 years of exploring space
we still receive a signal from Voyager 1.
Elsewhere in the solar system,
another world awaited our arrival.
New Horizons, for me, is probably the most exciting mission
that's been mounted in the last, certainly several years,
perhaps decades, because it was a mission to a new place,
to a new world and that world, Pluto, we knew nothing about.
And that's exploration at its best.
It's always the case that if you go somewhere new
that you've never been before, you make unexpected discoveries.
And New Horizons did not disappoint.
After nine years of flight,
New Horizons awoke.
We had our first glimpse of the most distant world ever visited.
Pluto is beautiful.
Far from being a frigid, featureless world,
it turns out that it has all the characteristics of a dynamic,
living planet.
Yes, it is cold on the surface,
about -230 degrees Celsius.
I'd be walking over solid nitrogen.
But the blotches that could be made out
in the grainy Hubble Space Telescope images
turned out to be a tremendous variety
of geological form and structure.
But by far the most recognisable feature
is the region known as Tombaugh Regio,
or to give it its more popular name, Pluto's Heart.
But there's something very strange about the region,
something that sets it apart from the rest of this dwarf planet.
The surface of Pluto is covered in craters - the scars of impacts
that have taken place over many billions of years
just like the surface of our moon.
Except, if you look on Sputnik Planitia,
it is absolutely smooth.
There are no craters there at all - not a single one.
Detailed imagery beamed back by New Horizons
revealed a network of hexagon and pentagon shapes...
that crisscross the frozen nitrogen surface.
A clue to what might be happening can be seen in these images.
Those kind of patterns are found elsewhere in nature.
Here, for example, on the surface of the sun.
Or here, in a liquid that's been heated from below.
These patterns are characteristic of convection.
There's a heat source, which is causing material to rise up
and then it cools and falls back again.
And in those circulating convection currents,
you tend to get patterns like this.
So, what could be happening below the surface of Sputnik Planitia
is that there is a heat source deep down which is melting
the nitrogen ice and causing it to rise, cool, and then fall again.
And those convection currents are constantly resurfacing the area.
Our best theory of how this could be is that somewhere
deep in its interior...
there are radioactive elements that generate heat as they decay.
Now, the evidence from Sputnik Planitia that there's still
an internal heat source
and studies of other geological features on Pluto
have led some scientists to suggest
that that ocean of water might still be there.
And the relatively warm ocean could explain
the lack of craters on Sputnik Planitia.
The entire area is constantly being repaved as the nitrogen surface
is slowly turned over.
Imagine that, an ocean,
billions of miles away from the sun,
on the frozen frontier of the solar system.
On this most surprising of worlds,
there may still be an ocean of water.
How far can we go?
With our current technology,
there are rough designs to build spacecraft
that can go to the nearest stars.
The nearest star, the Alpha Centauri system,
is about four light years away.
That's a tremendously long journey...
but it's a journey, with current technology,
that we could imagine making in 100 years, let's say.
Is there a limit to our exploration?
Well, there may be limits to our physical exploration,
but there are no limits to our intellectual exploration.
In our imaginations,
using science to travel,
then we can explore out to the edge of the observable universe.
So, I would say there is no limit
to the potential of human exploration.
Why do we feel the need to continue to explore?
There's a deeper question here which goes to the very heart
of the question, what does it mean to be human?
One of my favourite quotes, TS Eliot.
He speaks about exploration.
He says, "We shall not cease from exploration.
"And the end of all our exploring
"will be to arrive where we started
"and know the place for the first time."
I always think of the pale blue dot image that Voyager 1 took.
That pixel is the only place we know of in the universe
where life exists.
It is our responsibility, therefore, to protect this pixel
and not to fight over it.
So, exploration gives us perspective.
And that's what Eliot means.
In order to understand your place,
in order to be able to comprehend your importance
and the beauty and privilege
of our position here in the universe,
you have to go away and look at that place from afar.
And that, to me, is the true value of exploration.
Next time, I'll be asking one of the most profound questions.
Are we alone in the universe?
We have hope that someday,
we will be in the right place at the right time.
A 72-second flash of radio waves.
This has become known as the "wow signal".
See you in eight hours.