All language subtitles for BBC The Sky at Night 2018 Expedition Asteroid Eng

This year, two missions will attempt
one of the most daring feats

in space exploration.

They will gather rock samples
from another world.

The spacecraft have been launched
to two different asteroids,

they'll gather samples, and they
will bring them back to Earth.

So, why the sudden interest
in asteroids,

and what can we learn from these
extraordinary missions?

Welcome to The Sky At Night.

When we think of the solar system,
we usually think of the planets,

moons and the sun.

But there's more to our
cosmic neighbourhood than that.

Gathered in a vast doughnut-shaped
ring between Mars and Jupiter are

millions of asteroids.

Some are up to 300 miles across.

Until now, we've only been able to
study asteroids - like this one -

when they've fallen to earth.

Or meteorites,
to give them their proper name.

But now, missions have been launched
to bring pieces of two different

asteroids back to Earth.

These samples could unlock secrets

about the origins of the
solar system...

..and could even help save Earth
from a catastrophic collision.

And so tonight, we're here at the
Natural History Museum in London,

home to the world's largest
collection of meteorites.

Coming up...

We'll see the alarming number
of asteroids

orbiting close to our planet.

The impact energy if that thing
entered the atmosphere would be

larger, 20 times larger than the
largest atomic device

built during the Cold War.

We'll talk to the scientists
attempting to bring pieces

of an asteroid back to Earth.

We have yet to have material brought
back to Earth from such a primitive

body that will give us answers to
possible origins of life on Earth.

And we'll meet the man who wants
to catch a shooting star.

But first, we need to know
a little more about asteroids.

Tim Gregory is here to explain

why they can tell us so much about
our solar system.

TIM: Here at the Natural History
Museum are thousands of samples

of rocks from across the earth.

Each one has a story to tell

about the geological forces
that shaped our planet.

But there is a limit to what these
rocks can tell us.

The rocks on the earth are
always changing.

They are being made and unmade and
remade by geological processes,

so there's only so far back in time
that these rocks can take us.

To look back to the very earliest
days of the Earth,

or even further back to before
the Earth formed, you need

something that's unchanged since the
beginning of the solar system.

And that's where asteroids come in.

The problem is getting our hands
on one.

But, fortunately, we do have some
fragments here on earth.

This one fell to the Earth on
Christmas Eve in 1965 in Barwell,

a village in Leicestershire.

It's a piece of an asteroid.

And when a piece of an asteroid
falls through the Earth's atmosphere

and lands on the ground,
we call it a meteorite.

Pieces of this rock showered
the streets.

Some fell through living room
windows and even damaged cars.

Bet it was quite a shock for
the residents

when this fell out the sky!

Slice open a meteorite and they
start to reveal their secrets.

Take a look at this one.

These white, fluffy objects

are called calcium aluminium
rich inclusions, or CAIs, and they

are some of the oldest material that
you can get your hands on

in our solar system today.

The CAIs were the first solid
material to condense out of

the solar nebula -

the disc of gas and dust that gave
birth to our solar system.

You cannot touch anything older
than this.

And it's by dating CAIs just like
this one that we know the age of our

solar system to be
4.6 billion years old.

Surrounding them are these small,
pale beads.

They're all round and that's because
they were once molten droplets of

rock that cooled and crystallised
under zero gravity.

They're called chondrules,

and they're a major building block
of asteroids.

And the black stuff holding it
all together?

That's called the matrix,
and it was once free-floating dust

that coalesced to help form
the asteroids.

And amazingly, the matrix
contains water.

For some rocks, like this one,

that's as far as their
evolution went.

It carried on orbiting the sun
for billions of years unchanged.

But some asteroids grew bigger and
bigger and bigger, until eventually,

they formed the planets.

Exactly how you go from specks of
dust to something

the size of a planet
is still not fully understood,

but we do know that it was a
violent process.

Written in some of these rocks
is evidence that asteroids were

colliding and breaking up

and melting and reforming early on
in the history of the solar system.

This meteorite originated from an
asteroid that got so big it melted

beyond all recognition.

This one probably formed when a
rocky asteroid and a metal asteroid

collided and mixed together.

This shows how one rocky asteroid
has fragmented on impact

with another metallic asteroid.

Bits of rock have embedded
themselves

within a molten, metal matrix.

Contained within meteorites are most
of the ingredients and some of the

instructions for how you build
a solar system,

but there are still many
unanswered questions,

and meteorites cannot help us
answer all of them.

For one thing, they fall through the
atmosphere at 30,000 miles an hour,

and develop this burned and charred
crust on their surface as they fall.

And once they've landed, they
quickly become contaminated.

To truly understand how our
solar system formed,

what we'd like are some rocks from
an asteroid out there in space,

pristine and unspoiled.

And we may not have long to wait...

There are currently two missions
attempting the seemingly impossible.

To chase down an asteroid in space,
land on it,

collect a sample and return
that sample to Earth.

First in the race -
a Japanese mission called Hayabusa2.

It recently arrived at asteroid
Ryugu, 190 million miles from Earth,

and it sent back these images.

The Hayabusa2 mission aims to bring
back a piece of Ryugu to help us

learn more about the history
of our solar system.

I spoke to Shogo Tachibana about the
plan now that the spacecraft

has arrived at its destination.

He's leading the team responsible
for collecting the samples.

Hello, Shogo. Yes, can you hear me?

I can hear you, we can't see you...
Oh, there you are.

Hello! Nice to talk to you.
Yeah, good to see you.

Thank you for talking to us today.

What's the spacecraft doing now?

OK, so Hayabusa2 recently arrived
at asteroid Ryugu on June 27.

The spacecraft has been remaining

at distance of about 20km

to observe the asteroid,

so we hope to very soon have a date
for our first sampling.

And how will that sampling be done?

We'll touch down on the surface
of the asteroid

and as soon as this happens,

a small projectile will be shot

at the surface of the asteroid

and ejected material will be

collected in a capture.

What are the challenges involved
with taking samples in this way?

So, we will need to be
very cautious.

The images of Ryugu have shown us

it's a very rough and bumpy surface.

A bumpy surface is a very dangerous
environment for the spacecraft,

because the rocks may damage
the probe.

So our engineering team is now
working hard to find a way

to make a safe touchdown.

Can you tell us how you're feeling,
and how the team are feeling?

Are people excited, or are
you nervous?

Excited and nervous.

And especially...
So I am in charge of sampling,

so we really need sample.

Good. Well, look, we all wish you
the very best of luck.

I hope it goes well.
Thank you so much.

I hope we'll get to talk to you
about the science from the mission

once you get your samples back.

Thank you very much.

Hayabusa2 is due to collect its
sample any day now.

It promises to answer questions
about our solar system's origins.

But there's another reason why
studying asteroids is so important.

There's an awful lot of them
flying out there in space,

but we know from Earth's history
that every now and then,

one of them will collide with us.

Were that to happen tomorrow,
the results could be cataclysmic.

To find out how likely this is,
and what we can do about it,

I met Alan Fitzsimmons.

So, Alan, how do we check asteroids
that we don't know about?

Well, we find asteroids the same way

that the ancient Greek astronomers
found or identified the planets.

Both planets and asteroids are
in orbit about our sun,

and so that means

over an hour or a few hours,

you will see it moving against the
background stars and galaxies.

And that's how we survey for
asteroids out there

in our solar system.

So, we can actually beam live to
Hawaii and find out what's happening

with the telescope at the moment?

That's right. What we're seeing here
are the data coming back from the

ATLAS Project in Hawaii.

That's two half-metre telescopes
surveying the night sky,

looking for near-Earth asteroids.

Although, tonight it's not looking
too good, unfortunately.

Because we can see from the weather
map we've got a very large storm

system, actually a hurricane,
south of the Hawaiian Islands.

But we can have a look at what the
telescopes found last night.

Oh, yes. And what we found
during the night,

it found a lot of objects
moving across the sky.

So, if we zoom in here we can
actually see

in this part of the sky,
over an hour this object has moved

from here down to here
in the night sky.

And this is a real near-Earth
object.

So, this is very important data

because this will allow us to refine
the orbit and the trajectory of this

asteroid, and it will give us a
little bit more insight into

where it's going over the next
100, 200 years.

So, you're detecting these asteroids
virtually every night,

but do we have a feel of how many
of them are out there?

I think we do now.

This shows the inner solar system

as we knew it 20 years ago
in the year 1998.

And what we see here are the orbits
of the planets,

the sun in the centre of the
solar system,

and every one of these blue dots is
one of the few hundred near-Earth

asteroids that were known then.

OK. And over the past 20 years,
the technology we have,

in terms of telescopes
and detectors,

have really allowed us to detect
many, many more objects.

I can illustrate the growth in our
knowledge of the near-Earth object

population by playing
this animation.

So here, we can see the asteroids
all rotating.

Yeah, and you can see them moving.

So you're tracking...
Whoa, OK!

That's suddenly quite a
massive increase.

And again... That side.

What we're seeing here is the effect
of the increase in the power of our

survey telescopes, which, every
clear night, are trying to look for

these moving objects.

That looks like thousands, and
it looks quite scary.

Well, there are thousands.

In fact, right now we've gone from
just a few hundred up to over 18,000

near-Earth objects,

and we find another 40 new ones
every month on average.

So, looking at this, we know where
these asteroids come from,

but how many near-Earth objects

are actually dangerous to us,
on Planet Earth?

Out of those 18,000, less than 2,000
are what we class as

potentially hazardous objects,

which come very close to the Earth's
orbit and are 140 metres across

or so, or larger.

So, what sort of impact with
something that size have?

Oh, it would be pretty, pretty
disastrous for that local region.

And, of course, the larger
the asteroid,

the more impact it would have.

Out of that 18,000, there's only
2,000 potentially hazardous?

Yes. So that's 2,000
potentially ticking time bombs?

And a case in point would be
the asteroid Bennu.

This is a 500 metre,

half a kilometre diameter,

near-Earth asteroid that isn't

going to approach us in the next 100

years or so, but towards the end of

the next century has about a

one in 2,700 chance of hitting
the Earth.

Sort of low probability,

but the impact, I guess,
would be devastating? Absolutely.

The impact energy if that thing
entered the atmosphere would

be larger, 20 times larger,

than the largest atomic device
built during the Cold War.

And you'd really want to know,
for example, exactly how big it is.

What is its mass?
What is its density?

How is it constructed,
exactly what is it made of?

Because all of that kind of
information would allow us to plan

a deflection mission should
the need arise.

Asteroid Bennu is a potential
threat.

So, to discover all they can
about it,

Nasa have sent the second of our

two asteroid missions,
known as OSIRIS-REx,

to intercept and to collect
a sample from it.

Right now, it's making its
final approach to the asteroid.

I spoke to Kerri Donaldson Hanna
from the OSIRIS-REx team.

She's got the difficult task of
helping to select which bit of

the asteroid to bring back to Earth.

Where is the spacecraft now,
and what's it doing?

OSIRIS-REx is on its way
to Bennu,

so it started its approach phase
in mid August.

And it's now about 2 million miles
away from Bennu,

and roughly 60 million miles away
from Earth.

And so what it means is we're
starting to get the first

initial images of Bennu and start
resolving what Bennu looks like.

It seems strange that you'd launch a
spacecraft somewhere without knowing

what your target looks like.

What do we know about
asteroid Bennu?

We do kind of have a basic idea
of Bennu's shape.

I mean, it just looks like a blob...
Yeah, yeah. ..to me.

But you can see that while we have
the basic shape information,

we still are missing a lot of
information about its surface,

including whether it's big boulders,

you know, where there's
lots of dust.

And you need to pick somewhere
to land,

which seems impossible with this
sort of information?

In early December, we start doing
our preliminary survey,

which means we start going into
orbit and we start mapping

its surface properties.

So all of this work is to identify
a single landing site

which OSIRIS-REx will then go
to take samples from.

How does that work? How do you get
a piece of an asteroid?

So, the spacecraft is going to

slowly make its way towards
the asteroid.

The sample head will just touch

the surface of the asteroid
for five seconds.

That's it?
Yeah, just for five seconds.

And in that five seconds, a burst of
nitrogen gas will be released,

which will loosen all the
surface material.

And it'll flush all the material
up into the sample head.

And how much material do you get,
if you're lucky?

We are hoping to get a minimum of
60g of sample.

It's not very much.
But up to two kilograms...

Oh, OK. ..of sample.
A couple of bags of sugar?

Yeah, yeah. On Earth.

What will your role and the role
of laboratories like this be?

They want to make sure they can go
somewhere where they know

they can actually touch down,
they will want to go somewhere safe,

so that's, you know, worries about
the spacecraft itself.

But then they also want to go
somewhere where they can actually

sample as much material as possible.

And they know that to get the
maximum amount of sample,

they need a fairly flat surface,

and they also need a fairly
boulder-free surface.

So we're going to be making spectral
maps based on visible

and near infrared reflected light,

as well as thermal infrared
radiation emitted from the surface.

So they'll pull all of these
different maps and try to pick

the best science value place
on the surface.

Hayabusa2 is due to return
its samples in 2020,

followed by OSIRIS-REx in 2023.

Now, that's a bit of a time to wait.

So in the meanwhile,

I want to find out what makes
these samples so special,

and what we hope to learn
about them.

I met with Ashley King, a geologist

working with the rock collection at
the Natural History Museum.

So, the samples you get will be
returned from an asteroid.

What makes them so special?

They'll be special because we're
getting them from an asteroid,

but also we'll have context.

So we'll know which asteroid they
come from and

whereabouts on the asteroid.

So, nearly all of the meteorites
that we have,

we're pretty sure they come from
asteroids but we don't know exactly

whereabouts, or which asteroids
they come from.

So, I'm a geologist, so what I do
here on Earth is when you go out,

you collect a sample,
you're actually...

I have something here
I can show you.

One you happen to have in your
back pocket.

I have in my back pocket,
like all good geologists!

This is a rock that was brought back
by Scott from Antarctica.

Oh, wow. So this is...
Can I hold it? Absolutely, yeah.

This is a piece of granite,
and so what we have here on Earth

is that you can go to the outcrop,
you can see the rocks, you can,

you know how that rock fits into the
bigger picture of that area.

Then you can bring that sample back
and study it in the laboratory.

Meteorites are brilliant because
we have the samples and we

can study them in the lab. But we
don't have that original context.

Where did they come from
on the asteroid?

What were the other rocks...
What did they look like?

How did they relate to each other?

For these rocks that come back
from Hayabusa2 and OSIRIS-REx,

we'll have that information

which as a geologist,
is completely invaluable.

What will be samples tell us
that we don't already know?

One of the big questions in
planetary science is where

did the Earth get its water from?

We know from the meteorite record
that they look like meteorites

that have water in them.

This isn't liquid water,

it's water that's locked up
within the minerals.

When we go there, we'll be able to
get samples and study the water

that's in these things and compare
it to what we see on the Earth.

Yeah, we don't really know where
the Earth's water came from.

We think maybe comets
was one option.

It turns out from missions
like Rosetta, have kind of shown

that the comets aren't the perfect
match for the water that we see

here on the Earth,
so hopefully asteroids,

or these asteroids, might give us
some clues to that.

How about life? Yeah.

The other interesting thing that
we're going to these asteroids,

to Bennu and to Ryugu, because
they are dark.

They are really black surfaces.

One of the reasons we think these
things are so dark is that they

probably got organic molecules

and the kind of building blocks
for life are in there.

These samples will be pristine,

so they won't have been altered in
the terrestrial atmosphere.

It'll be really exciting to see
whether asteroids like this are

one of the ways that we can bring
the starting materials for life.

But as well as life,

asteroids threaten to deliver
death and destruction to our planet.

Some of these near-Earth asteroids
are actually potentially hazardous.

There's a possibility,
a very small possibility,

that they could collide with the
Earth at some point in the future.

So, one of the reasons we want to go
and study these things is to

understand the composition,
the structure.

Hopefully, if something was going
to hit the Earth,

we can plan a bit about

how we would deal with that
kind of problem.

So, if we detect dangerous asteroid,
what can we do about it?

I mean, Bruce Willis blew it up.
Is that a good idea?

So, that's one thing
that's discussed.

There's ideas, particularly
for these dark ones,

there's this idea that we could go
and paint one side white

and the solar radiation would just
nudge it off of its course

ever so slightly.

It's all about trying to change the
orbital path just enough

so that it won't hit the Earth.

I suppose, the more we know
about them,

the more effective that will be.
Yes. Thank you.

Whilst we wait for samples from
the two different missions,

technology is giving us new ways to
understand more about asteroids

from here on Earth.

Pete Lawrence shows how you
can get involved.

PETE: When small pieces of rock
pass-through Earth's atmosphere,

they leave a bright light in the sky
called a meteor or a fireball.

I've been fascinated by meteors

and indeed fireballs for the past
40 years or so.

And over that time, I've taken
tens of thousands of images.

And I've been lucky enough

to capture several hundred
meteor trails.

But tonight, I'm going to try
something different.

I'm going to try and capture
meteor trails using a video camera.

Now, the camera I'm going to use is
a bog-standard security CCTV camera,

and this is powered so that it
comes on as the sun sets,

and the power's taken off via a
timer when the sun rises.

Now, I'm going to set this up
permanently

so it's looking for fireballs
all year round.

And to do that, I need to use
a weatherproof housing,

and this is a fairly bog-standard
bit of kit as well.

The camera needs to point at a
clear patch of sky,

so I'm mounting mine onto the
side of my garden shed.

The camera is connected to an
ordinary computer with software

that will identify and record
any fireballs that occur.

Now, I've only had my camera set-up
for the past couple of nights,

but rather excitingly,

I have managed to capture a number
of meteor trails over that period.

I've got a very nice one here that's
running down the sky beautifully

against the stars of Pegasus.

They are not particularly
bright meteors,

but they have recorded really well

with this actually quite simple
set-up.

The great thing is that, with it,

I can join the UK Meteor Observation
Network, or UKMON, as they're known.

This is a group of amateur
astronomers

that have set up cameras
all over the UK.

And if you do so and you catch
a meteor trail passing through the

field of view of your camera, the

likelihood is that another camera
will have picked it up as well.

If that happens, then you can
work out the height of the meteor,

its speed, and also,

you can track it back to work out
the particle's orbit that created

the meteor in the first place.

So, you're doing real
meteor science.

Tracking where meteors come from
is important work.

But there's a bigger prize.

Most meteors are nothing more than
tiny sand-sized particles

that burn up in the atmosphere.

But some are big enough to make it
to the ground.

Like this one that was filmed over
Perth fewer than two weeks ago.

Luke Daly is helping to set up a
global network of cameras

to not only track, but to recover
meteorites that have hit the Earth.

One of his cameras is on the roof of
a stately home in North Yorkshire.

We're setting up a network
of ten cameras here in the UK.

Basically, like this one.

It's got a nice fish-eye lens,

so we see the entire night sky
all the time.

It takes 30-second-long exposures.

And so, if a fireball comes through
our images,

we see it on this camera,
and hopefully we see it

on another camera and we can
start sort of seeing what's

flying around up in the atmosphere
at all times across in the UK.

The camera's been down for
the last few nights,

and so Luke has come to carry out
some vital maintenance.

Getting to the camera's very easy,

it's just these three Phillips head
screws - we just wind them off.

Then this top just pops off like so.

As I suspected, we've got this
card read error.

Now we just need to see if it'll
take a picture for us.

Once all of the cameras
are up and running,

Luke and his team will be able to
see all of the meteorites

that land anywhere within the UK.

He hasn't found any yet,
but the concept has been proven.

He helped set up a similar network
under the clear skies of Australia,

which has seen success.

So, when multiple cameras
see the same event,

we are able to quite precisely
mapped that trajectory.

In Australia, three of our stations
so the same event,

and we were able to get that
trajectory,

triangulate it down to the ground,

figure out very precisely
where it landed.

In 2016, these images of the
same fireball

led one of Luke's colleagues
to a remote location

in the Australian desert.

Buried half a metre into thick mud

was a two-kilo meteorite.

It's an iron meteorite, mate.
Oh, my gosh!

Phil, how does it feel to find
your first DFN meteorite?

Splendid!

LUKE LAUGHS

So, as well as getting the full
position of these rocks,

we can also track it back into
our solar system

and get its orbit really precisely.

And from that, we can start to
figure out where these rocks

are coming from, and even what
asteroid or asteroid family

they're originating from.

Luke's team are working on a method
to calculate the precise journey

that each rock has taken before
landing here on Earth.

So, understanding where meteorites
come from as the sort of oldest

material, and understanding how
that has evolved over time,

and how our solar system
has evolved, gives us a...

Sort of enhances our understanding
of how the planets form,

how our planet formed,
what's special about our planet

that it developed life
when others didn't.

Much of what we know about the early
solar system comes from studying

asteroids and meteorites.

Yes, cos these are time capsules,
relics from the past,

and they tell us about our origins.

But there's still a lot to learn.

That's where Hayabusa2 and
OSIRIS-REx come in.

The samples they return will give us
an unprecedented window into the

history of the early solar system.

As to what they'll find,
we'll just have to wait and see.

But we'll be here to tell you
all about it.

Goodnight.