1
00:00:09,940 --> 00:00:15,380
3.5 billion miles from Earth,
beyond Jupiter,

2
00:00:15,380 --> 00:00:20,060
Saturn, past Uranus and Neptune

3
00:00:20,060 --> 00:00:23,060
hides Pluto and its five moons.

4
00:00:26,100 --> 00:00:28,020
Discovered in 1930,

5
00:00:28,020 --> 00:00:31,220
for decades we knew almost
nothing about it.

6
00:00:33,860 --> 00:00:38,100
As a child, I learned that Pluto
was a mysterious grey rock.

7
00:00:40,980 --> 00:00:46,500
So in 2006, NASA launched a rocket
carrying a lightweight probe.

8
00:00:46,500 --> 00:00:48,500
All telemetry is nominal.

9
00:00:48,500 --> 00:00:51,380
Copy that. We have a healthy
spacecraft.

10
00:00:53,460 --> 00:00:56,700
The spacecraft returned
the first-ever close-up images

11
00:00:56,700 --> 00:00:58,740
of Pluto's surface.

12
00:00:58,740 --> 00:01:01,700
We've recorded data of the
Pluto system.

13
00:01:03,300 --> 00:01:07,380
And sent our understanding
of this icy world into disarray.

14
00:01:09,460 --> 00:01:14,100
The data returned has forced us
to rethink everything about Pluto.

15
00:01:15,180 --> 00:01:18,500
This was not the lifeless rock we
once thought.

16
00:01:20,100 --> 00:01:22,900
There is a heat source which must be
coming from inside,

17
00:01:22,900 --> 00:01:26,500
but the details of that
are still very mysterious.

18
00:01:29,340 --> 00:01:35,660
This small, unassuming little world
may actually have a liquid water

19
00:01:35,660 --> 00:01:38,060
ocean beneath its icy surface.

20
00:01:40,900 --> 00:01:43,980
Incredible new discoveries
about Pluto are even

21
00:01:43,980 --> 00:01:46,980
changing our understanding
of life beyond Earth.

22
00:01:48,020 --> 00:01:50,740
No-one in their right mind would
have thought Pluto had life,

23
00:01:50,740 --> 00:01:52,300
but now it's a possibility

24
00:01:52,300 --> 00:01:54,700
and that in itself is kind of
mind-blowing.

25
00:01:57,380 --> 00:02:01,220
This is the story of how Pluto
came back from the dead.

26
00:02:19,540 --> 00:02:23,540
In 2006, a visionary group
of scientists began

27
00:02:23,540 --> 00:02:25,380
a ground-breaking mission.

28
00:02:26,820 --> 00:02:30,060
To send a spaceship further
than ever before.

29
00:02:32,100 --> 00:02:36,620
Its mission - to explore the far
reaches of our solar system and take

30
00:02:36,620 --> 00:02:39,660
the first-ever close-up image
of Pluto,

31
00:02:39,660 --> 00:02:42,100
before continuing into deep space.

32
00:02:47,020 --> 00:02:49,460
The probe was called New Horizons.

33
00:02:52,420 --> 00:02:56,300
And it would take more than nine
years to make the

34
00:02:56,300 --> 00:02:59,300
3.5-billion-mile voyage to Pluto.

35
00:03:05,740 --> 00:03:09,660
Keeping things on track was mission
operations manager Alice Bowman.

36
00:03:11,540 --> 00:03:15,980
This is the best picture of Pluto
that we had before New Horizons

37
00:03:15,980 --> 00:03:17,820
arrived, and this was taken

38
00:03:17,820 --> 00:03:19,860
by the Hubble Space Telescope

39
00:03:19,860 --> 00:03:25,060
and it was the picture that inspired
us to send a spacecraft to Pluto.

40
00:03:30,020 --> 00:03:34,780
In 2015, ten days before
New Horizons' arrival,

41
00:03:34,780 --> 00:03:38,740
Alice's team began uploading
computer commands to the probe,

42
00:03:38,740 --> 00:03:44,020
telling the spacecraft what to do
when it reached Pluto.

43
00:03:47,060 --> 00:03:50,220
That was a very anxious time
because we wanted to make sure

44
00:03:50,220 --> 00:03:53,580
that those commands were received
and accepted by the spacecraft,

45
00:03:53,580 --> 00:03:56,220
because if they weren't,
we wouldn't have a mission.

46
00:03:59,060 --> 00:04:04,100
But as the final command was sent,
Alice's worst fears were realised.

47
00:04:06,540 --> 00:04:09,780
We lost comm with the spacecraft.

48
00:04:11,900 --> 00:04:16,420
Totally silent. And so you can
imagine when you're in any kind of

49
00:04:16,420 --> 00:04:20,220
critical situation, the worst thing
is lack of any information.

50
00:04:20,220 --> 00:04:22,820
And that's essentially what we had.

51
00:04:26,260 --> 00:04:29,420
The team had lost all contact
with the probe.

52
00:04:31,980 --> 00:04:35,940
Pluto Ace MOM on New Horizons,
Pluto One.

53
00:04:35,940 --> 00:04:40,740
Could you advise why we are not
locking up to telemetry?

54
00:04:40,740 --> 00:04:44,540
MOM, stand by. I'll check with the
station on the status of telemetry.

55
00:04:46,780 --> 00:04:51,660
New Horizons was designed to
fly past Pluto, taking pictures

56
00:04:51,660 --> 00:04:52,740
as it went.

57
00:04:55,300 --> 00:04:57,700
If they didn't regain contact,

58
00:04:57,700 --> 00:05:00,860
it would fly past without
recording a thing.

59
00:05:03,500 --> 00:05:05,780
Station 43 Pluto Ace.

60
00:05:05,780 --> 00:05:09,460
MOM on New Horizons Pluto One,
go ahead, Pluto Ace.

61
00:05:09,460 --> 00:05:11,580
After a frantic hour, the team

62
00:05:11,580 --> 00:05:14,340
received a weak signal from
the probe.

63
00:05:16,100 --> 00:05:19,300
We found the spacecraft,
it was responding to us,

64
00:05:19,300 --> 00:05:23,100
it was giving us information,
but it was in a state that could not

65
00:05:23,100 --> 00:05:25,620
accomplish the encounter with Pluto.

66
00:05:29,660 --> 00:05:33,740
We determined that we had asked the
processor on board the spacecraft

67
00:05:33,740 --> 00:05:36,460
to do too many labour-intensive
things.

68
00:05:39,020 --> 00:05:43,020
And the spacecraft switched over to
the redundant or backup computer.

69
00:05:44,260 --> 00:05:48,180
New Horizons was back online,
but there was a problem.

70
00:05:49,940 --> 00:05:53,900
When it had switched to the backup
computer, it had wiped every line

71
00:05:53,900 --> 00:05:57,260
of command needed for its encounter
with Pluto.

72
00:05:58,700 --> 00:06:02,180
All non-essential systems
had shut down,

73
00:06:02,180 --> 00:06:03,780
including the cameras.

74
00:06:04,820 --> 00:06:09,260
The question became, did we have
enough time to recover

75
00:06:09,260 --> 00:06:13,100
the spacecraft and start
that flyby encounter on time?

76
00:06:14,340 --> 00:06:19,980
So our plan was to switch back to
the main computer and then resend

77
00:06:19,980 --> 00:06:22,660
the commands to the spacecraft.

78
00:06:22,660 --> 00:06:26,940
And it took us three days to
do that.

79
00:06:26,940 --> 00:06:29,340
Round the clock? Around the clock.

80
00:06:29,340 --> 00:06:32,180
We slept in our offices.

81
00:06:32,180 --> 00:06:36,460
No-one wanted to leave because we
had waited all this time

82
00:06:36,460 --> 00:06:38,500
and there was no way that we were

83
00:06:38,500 --> 00:06:40,740
going to let this opportunity
slip by.

84
00:06:44,220 --> 00:06:45,900
Working through the night,

85
00:06:45,900 --> 00:06:48,660
the team re-uploaded the
computer commands.

86
00:06:50,060 --> 00:06:53,580
Once completed, all they could do
was wait.

87
00:06:56,780 --> 00:06:58,820
It was a very anxious time.

88
00:07:01,420 --> 00:07:07,140
Travelling past Pluto more than ten
times faster than a speeding bullet

89
00:07:07,140 --> 00:07:09,580
meant every new line of command

90
00:07:09,580 --> 00:07:12,740
needed to work with
meticulous precision.

91
00:07:16,260 --> 00:07:18,220
There would be no second chance.

92
00:07:18,220 --> 00:07:19,540
No way to go back.

93
00:07:21,980 --> 00:07:25,420
And with New Horizons busy
collecting data,

94
00:07:25,420 --> 00:07:28,060
it would be out of contact
with Earth.

95
00:07:29,700 --> 00:07:32,540
Until the spacecraft beamed
back a signal,

96
00:07:32,540 --> 00:07:36,780
the team would have no idea
if the new commands had worked.

97
00:07:41,860 --> 00:07:46,260
Subsystems, please report
your status as you get enough data.

98
00:07:48,900 --> 00:07:50,980
OK, we're in lock with carrier.

99
00:07:50,980 --> 00:07:52,500
Stand by for telemetry.

100
00:07:52,500 --> 00:07:55,700
The atmosphere was very intense.

101
00:07:55,700 --> 00:07:59,380
We were all anxiously awaiting
that first bit of telemetry to tell

102
00:07:59,380 --> 00:08:01,980
us that the spacecraft had survived.

103
00:08:01,980 --> 00:08:04,300
MOM on Pluto One.

104
00:08:04,300 --> 00:08:07,260
We have a healthy spacecraft.

105
00:08:07,260 --> 00:08:10,900
We've recorded data
of the Pluto system.

106
00:08:10,900 --> 00:08:12,740
And we're outbound from Pluto.

107
00:08:12,740 --> 00:08:15,180
WHOOPING AND CHEERING

108
00:08:17,020 --> 00:08:18,780
The flyby was a success.

109
00:08:21,540 --> 00:08:25,900
And Pluto's surface came into focus
for the very first time.

110
00:08:28,740 --> 00:08:29,820
It was amazing.

111
00:08:31,500 --> 00:08:35,940
It just blew our minds that
something could be so beautiful.

112
00:08:35,940 --> 00:08:38,260
It's like telling us, "Why the heck

113
00:08:38,260 --> 00:08:40,580
"did you wait so long to
come visit us?"

114
00:08:43,020 --> 00:08:46,900
What New Horizons sent back was
astonishing.

115
00:09:00,300 --> 00:09:04,780
The probe had taken thousands
of photographs of Pluto's surface.

116
00:09:06,380 --> 00:09:09,580
Multiple cameras had charted
the topography.

117
00:09:11,380 --> 00:09:15,180
The spectrograph detected
what that surface was made from.

118
00:09:16,940 --> 00:09:20,100
Revealing Pluto's secrets
for the first time.

119
00:09:21,620 --> 00:09:23,420
And in spectacular detail.

120
00:09:26,260 --> 00:09:30,340
Oh, there's my friend! Beautiful.

121
00:09:31,380 --> 00:09:36,420
Leslie Young and Jeff Moore are two
of the project's leading scientists.

122
00:09:37,980 --> 00:09:42,700
Their job - to decipher
this mysterious alien world.

123
00:09:45,940 --> 00:09:48,940
It's amazing, you look at all
these exotic features.

124
00:09:48,940 --> 00:09:53,260
Everything's so amazing
and so diverse and so complex.

125
00:09:53,260 --> 00:09:57,460
I was in the main room when I first
saw this image.

126
00:09:57,460 --> 00:09:59,180
We were on tenterhooks.

127
00:10:03,260 --> 00:10:07,300
Pluto was ready for its close-up.

128
00:10:08,740 --> 00:10:11,780
When these images arrived,
the team was struck

129
00:10:11,780 --> 00:10:14,020
by Pluto's familiar appearance.

130
00:10:15,580 --> 00:10:18,660
These mountains down here, they look
an awful lot like Earth mountains.

131
00:10:18,660 --> 00:10:20,020
They're snow-capped.

132
00:10:20,020 --> 00:10:25,060
These guys are 4km tall,
just like the Rocky Mountains are.

133
00:10:27,820 --> 00:10:32,500
But unlike Earth, these mountains
were made from ice, not rock.

134
00:10:36,780 --> 00:10:39,420
Pluto is so far from the sun,

135
00:10:39,420 --> 00:10:44,060
the scientists were expecting
an almost featureless frozen sphere.

136
00:10:45,100 --> 00:10:48,340
Instead, New Horizons had revealed

137
00:10:48,340 --> 00:10:50,580
Pluto to be a world of puzzling
complexity.

138
00:10:52,220 --> 00:10:54,860
There were mountains forged
from ice.

139
00:10:56,420 --> 00:10:58,020
Craters of every size.

140
00:10:59,500 --> 00:11:02,140
Gaping canyons and vast plains

141
00:11:02,140 --> 00:11:05,780
covered in nitrogen frost
and methane snow.

142
00:11:08,020 --> 00:11:11,180
All of it mysteriously coloured
from deep red...

143
00:11:12,620 --> 00:11:13,940
..to bright white.

144
00:11:13,940 --> 00:11:17,500
We knew Pluto was going to be
scientifically astonishing.

145
00:11:17,500 --> 00:11:21,020
We didn't know it was going to be
so beautiful.

146
00:11:21,020 --> 00:11:23,940
Nobody expected to see anything
like this.

147
00:11:31,020 --> 00:11:35,620
Pluto's full glory had finally
been revealed,

148
00:11:35,620 --> 00:11:41,140
85 years after it was discovered by
American astronomer Clyde Tombaugh.

149
00:11:44,220 --> 00:11:46,860
Its distance from Earth has meant
that for much of the time

150
00:11:46,860 --> 00:11:50,700
that we've known about it,
Pluto has remained as mysterious

151
00:11:50,700 --> 00:11:53,340
as the stories that inspired
its name.

152
00:11:54,980 --> 00:11:58,380
Pluto is the god of the underworld
in mythology.

153
00:11:58,380 --> 00:12:01,260
He lives in the realm underground.

154
00:12:01,260 --> 00:12:03,820
And this is the place where people
go when they die.

155
00:12:07,260 --> 00:12:11,620
The first thing to know about Pluto
is that it's tiny.

156
00:12:11,620 --> 00:12:13,060
And really far away.

157
00:12:14,780 --> 00:12:17,540
We're standing on a lake bed,
a frozen lake in Colorado.

158
00:12:17,540 --> 00:12:21,060
Let's pretend that this is the plane
of the solar system.

159
00:12:21,060 --> 00:12:24,020
And over there, the ice resurfacing
machine,

160
00:12:24,020 --> 00:12:26,060
we'll call that the sun.

161
00:12:26,060 --> 00:12:29,060
That's where the sun is, then we're
roughly where Earth is.

162
00:12:29,060 --> 00:12:32,740
But, of course, Earth is much
smaller. If I don't break it,

163
00:12:32,740 --> 00:12:35,380
here is the Earth, roughly a
centimetre across,

164
00:12:35,380 --> 00:12:36,700
something like that.

165
00:12:36,700 --> 00:12:40,060
Now, Pluto, by comparison,
would be a grain of sand.

166
00:12:40,060 --> 00:12:42,740
That grain of sand would not
be here, of course, in this part

167
00:12:42,740 --> 00:12:44,820
of the solar system, it's in the
outer part.

168
00:12:44,820 --> 00:12:47,980
And it would be roughly on that
mountaintop right over there.

169
00:12:47,980 --> 00:12:51,020
So about 6km
away would be Pluto.

170
00:12:54,180 --> 00:12:56,540
Pluto's extreme distance from Earth

171
00:12:56,540 --> 00:13:00,180
meant that very little was known
about it before

172
00:13:00,180 --> 00:13:02,020
New Horizons arrived.

173
00:13:02,020 --> 00:13:05,700
Astronomers knew that it was
cold enough to be made from ice.

174
00:13:06,900 --> 00:13:09,300
They knew it was small,

175
00:13:09,300 --> 00:13:11,980
and that it had company.

176
00:13:11,980 --> 00:13:15,220
Pluto is not alone.
In fact, it has five moons.

177
00:13:16,820 --> 00:13:19,420
Tiny Pluto isn't one body,

178
00:13:19,420 --> 00:13:22,540
but a whole system of icy worlds

179
00:13:22,540 --> 00:13:26,380
all engaged in a strange
and complex dance.

180
00:13:28,220 --> 00:13:32,860
And as New Horizons approached
Pluto, the scientists were able

181
00:13:32,860 --> 00:13:36,140
to see them in detail
for the very first time.

182
00:13:38,620 --> 00:13:41,580
Pluto's first and largest moon
is Charon.

183
00:13:43,860 --> 00:13:47,500
The name comes from Greek mythology
as the name of the boatman

184
00:13:47,500 --> 00:13:50,300
who would row people across
the river to get them

185
00:13:50,300 --> 00:13:52,140
to the underworld.

186
00:13:52,140 --> 00:13:54,380
Charon is remarkably large
compared to Pluto.

187
00:13:54,380 --> 00:13:57,740
It's about half the size
and they're very close.

188
00:13:58,860 --> 00:14:02,740
Sometimes we call them a binary
planet because, in fact, they orbit

189
00:14:02,740 --> 00:14:05,580
together as if there were a rod
between them and they were two ends

190
00:14:05,580 --> 00:14:07,260
of a lopsided dumbbell.

191
00:14:09,140 --> 00:14:12,620
Pluto's moon Charon doesn't orbit
Pluto.

192
00:14:12,620 --> 00:14:15,580
Unusually, they orbit each other...

193
00:14:16,700 --> 00:14:19,100
..around a point in empty space.

194
00:14:21,460 --> 00:14:25,780
Beyond Charon are four smaller
moons. There's Styx.

195
00:14:25,780 --> 00:14:30,300
Styx is the river that the boatsman,
Charon, would take people across

196
00:14:30,300 --> 00:14:33,420
once they died and entered
the underworld itself.

197
00:14:33,420 --> 00:14:37,260
Styx is a very small body, it's just
kind of a lumpy, irregular object.

198
00:14:39,780 --> 00:14:40,940
There's Nix.

199
00:14:42,340 --> 00:14:45,100
Nix is about 50km across.

200
00:14:45,100 --> 00:14:47,820
It is rotating in a very strange
way that we haven't quite

201
00:14:47,820 --> 00:14:49,060
figured out yet.

202
00:14:52,300 --> 00:14:55,740
Then there's Kerberos

203
00:14:55,740 --> 00:14:57,220
and Hydra.

204
00:14:58,780 --> 00:15:03,260
Hydra is spinning very, very fast
and we simply don't know why.

205
00:15:05,140 --> 00:15:09,980
If you were standing on Hydra,
you might have to actually hold on.

206
00:15:11,820 --> 00:15:15,220
Why does a tiny dwarf planet
have so many moons?

207
00:15:16,900 --> 00:15:20,340
The peculiar dance of Charon
and Pluto are a clue.

208
00:15:21,980 --> 00:15:25,060
So the big question, of course,
is you have to get two bodies,

209
00:15:25,060 --> 00:15:27,300
you have to get a binary planet
in the middle.

210
00:15:27,300 --> 00:15:30,700
And the only way we really know to
do that is there was a proto-Pluto

211
00:15:30,700 --> 00:15:33,740
out there very early in the history
of the solar system.

212
00:15:33,740 --> 00:15:36,540
And something else hit it,
something very, very big.

213
00:15:41,060 --> 00:15:42,860
Pluto kind of blew apart.

214
00:15:46,300 --> 00:15:48,220
And eventually re-coalesced.

215
00:15:50,220 --> 00:15:52,220
But all that material
that was floating around,

216
00:15:52,220 --> 00:15:54,660
a lot of it formed into Charon.

217
00:15:57,940 --> 00:16:00,660
And the two got kind of stuck
together as they evolved

218
00:16:00,660 --> 00:16:04,020
into this perfect circular
dumbbell system.

219
00:16:04,020 --> 00:16:07,860
Maybe there was some debris
left over that landed further out

220
00:16:07,860 --> 00:16:11,540
and that became Hydra, and Kerberos,
and Nix and Styx.

221
00:16:14,100 --> 00:16:17,460
New Horizons had given the
scientists a better understanding

222
00:16:17,460 --> 00:16:19,380
of Pluto's peculiar moons.

223
00:16:21,100 --> 00:16:24,420
But it was the pictures of Pluto's
surface that contained

224
00:16:24,420 --> 00:16:25,940
the biggest surprises.

225
00:16:30,100 --> 00:16:33,700
A smaller impact than the one
that created the moons

226
00:16:33,700 --> 00:16:37,740
could be responsible for one of
Pluto's most mysterious features.

227
00:16:41,500 --> 00:16:43,460
We think this was a big impact

228
00:16:43,460 --> 00:16:46,300
crater just from the shape of it,
really.

229
00:16:46,300 --> 00:16:51,260
This is probably an ancient crater
rim of a huge impact

230
00:16:51,260 --> 00:16:55,820
that must have happened early on
when Pluto was still very young.

231
00:16:55,820 --> 00:16:58,260
So this is about 1,000km across,

232
00:16:58,260 --> 00:17:01,740
probably something about 200km
across came in and hit Pluto.

233
00:17:03,980 --> 00:17:08,540
New Horizons was carrying a
spectrograph, an instrument capable

234
00:17:08,540 --> 00:17:11,740
of analysing chemical composition.

235
00:17:11,740 --> 00:17:15,220
It revealed that much of Pluto's
freezing surface was covered

236
00:17:15,220 --> 00:17:16,740
by soft nitrogen ice.

237
00:17:19,180 --> 00:17:24,060
Normally a gas on Earth, the
scientists believe that vast amounts

238
00:17:24,060 --> 00:17:28,700
of it have flowed in to fill
this enormous crater.

239
00:17:28,700 --> 00:17:32,620
We're pretty sure we understand
that what makes up the plain

240
00:17:32,620 --> 00:17:38,380
is a vast reservoir of solid
nitrogen ice,

241
00:17:38,380 --> 00:17:41,580
which even though it's solid,
is very soft.

242
00:17:43,700 --> 00:17:47,180
It was like a glacier,
but made from nitrogen ice.

243
00:17:48,660 --> 00:17:52,260
The area was informally dubbed
Pluto's heart

244
00:17:52,260 --> 00:17:54,500
after its obvious resemblance.

245
00:17:55,740 --> 00:17:59,260
But closer inspection left
the scientists with a puzzle.

246
00:18:00,620 --> 00:18:05,180
It had all these weird forms
and textures on the surface.

247
00:18:05,180 --> 00:18:08,460
Some stand up quite clearly,
some are very subtle.

248
00:18:11,540 --> 00:18:16,060
An intricate and strangely organised
pattern appeared to be scribed

249
00:18:16,060 --> 00:18:18,500
into the surface of the
nitrogen ice.

250
00:18:19,740 --> 00:18:22,140
And there was something missing.

251
00:18:23,260 --> 00:18:26,420
The other thing that struck us
was the fact there was no impact

252
00:18:26,420 --> 00:18:29,140
craters anywhere in this
huge expanse.

253
00:18:31,980 --> 00:18:36,580
Ancient planetary surfaces are
almost always covered in craters.

254
00:18:38,380 --> 00:18:41,940
A result of being battered by
asteroids over billions of years.

255
00:18:44,460 --> 00:18:48,940
And much of Pluto's surface was
heavily cratered,

256
00:18:48,940 --> 00:18:51,380
but here there were none.

257
00:18:55,100 --> 00:18:57,100
Nobody imagined there'd be
a huge region

258
00:18:57,100 --> 00:19:00,300
that was many hundreds of kilometres
long and wide

259
00:19:00,300 --> 00:19:02,140
that would be completely
devoid of craters.

260
00:19:02,140 --> 00:19:03,820
That was mind-blowing.

261
00:19:03,820 --> 00:19:08,060
What's forming this huge plain
has to be an ongoing process.

262
00:19:12,140 --> 00:19:15,660
Jeff believed that whatever force
had created these shapes must

263
00:19:15,660 --> 00:19:18,220
still be operating on Pluto today.

264
00:19:20,820 --> 00:19:22,460
This isn't an extinct world,

265
00:19:22,460 --> 00:19:24,780
this is an active world
in which geological processes

266
00:19:24,780 --> 00:19:26,540
are operating today and they're

267
00:19:26,540 --> 00:19:29,140
destroying any evidence
for past cratering.

268
00:19:29,140 --> 00:19:31,180
And that was truly remarkable.

269
00:19:33,020 --> 00:19:35,860
It was a monumental discovery.

270
00:19:35,860 --> 00:19:39,540
This was not the dead world
that everyone thought.

271
00:19:39,540 --> 00:19:40,860
Pluto's heart...

272
00:19:42,180 --> 00:19:43,820
..appeared to be beating.

273
00:19:55,380 --> 00:20:00,140
The scientists' job now was to find
out what was driving it.

274
00:20:00,140 --> 00:20:02,100
All right, Mary. Commercial break.

275
00:20:02,100 --> 00:20:06,540
We got 1:45 when we get to you.
1:45. OK. Coming out to you guys
here

276
00:20:06,540 --> 00:20:08,260
in five, four, three...

277
00:20:09,980 --> 00:20:12,420
Welcome to KPIX 5 News At Noon.

278
00:20:13,860 --> 00:20:17,500
The New Horizons planetary
scientists were stumped.

279
00:20:18,980 --> 00:20:21,860
Mysterious patterns appear
to be carved into the surface

280
00:20:21,860 --> 00:20:24,420
of the nitrogen glacier.

281
00:20:24,420 --> 00:20:26,060
..dry and quiet conditions,

282
00:20:26,060 --> 00:20:30,700
milder weather expected Wednesday,
Thursday and especially for Friday.

283
00:20:30,700 --> 00:20:33,340
Meteorologist Mary Lee was

284
00:20:33,340 --> 00:20:36,220
not involved in the
New Horizons mission,

285
00:20:36,220 --> 00:20:39,540
but to her the shapes are a
familiar sight.

286
00:20:42,100 --> 00:20:44,500
That's going to do it for a
KPIX 5 News At Noon.

287
00:20:44,500 --> 00:20:46,500
Have a wonderful afternoon.

288
00:20:46,500 --> 00:20:48,220
I am the morning meteorologist

289
00:20:48,220 --> 00:20:52,220
for the CBS station here
in the Bay Area, KPIX 5.

290
00:20:52,220 --> 00:20:55,820
I wake up at 2:30 to start my day.

291
00:20:55,820 --> 00:20:59,140
When I'm putting the forecast
together I'm really looking at

292
00:20:59,140 --> 00:21:02,540
satellite data so we can determine
the clouds

293
00:21:02,540 --> 00:21:04,860
that are over our region.

294
00:21:04,860 --> 00:21:08,300
Mary is paying special attention
to the clouds forming

295
00:21:08,300 --> 00:21:10,540
over the Pacific Ocean.

296
00:21:10,540 --> 00:21:13,580
These are stratocumulus clouds.

297
00:21:13,580 --> 00:21:19,500
So really you can see that puffy,
lumpy texture of those cloud tops.

298
00:21:19,500 --> 00:21:21,860
These clouds are very common
on the west coast

299
00:21:21,860 --> 00:21:23,060
of the Pacific Ocean.

300
00:21:23,060 --> 00:21:26,500
So here in the Bay Area,
we see them all the time.

301
00:21:26,500 --> 00:21:30,220
You can actually see the boundaries
of these clouds and it kind of forms

302
00:21:30,220 --> 00:21:33,100
a bit of a hexagonal shape
across our atmosphere.

303
00:21:34,220 --> 00:21:38,500
These repeating shapes are
very similar to what scientists see

304
00:21:38,500 --> 00:21:39,740
in Pluto's heart.

305
00:21:41,580 --> 00:21:45,260
They're a result of a unique way
that these clouds are formed.

306
00:21:46,500 --> 00:21:49,260
I love looking at these
stratocumulus clouds.

307
00:21:49,260 --> 00:21:51,460
They form over the Pacific Ocean.

308
00:21:51,460 --> 00:21:55,020
And really what happens, you have
the sun hitting the surface,

309
00:21:55,020 --> 00:21:58,660
that warm air rises and the liquid
droplets, they condense

310
00:21:58,660 --> 00:22:00,940
and so they form these clouds.

311
00:22:00,940 --> 00:22:03,540
And the top of these clouds,
it's very cold air.

312
00:22:03,540 --> 00:22:05,660
So that cold air sinks.

313
00:22:05,660 --> 00:22:08,540
This process is called convection.

314
00:22:08,540 --> 00:22:12,260
You have this cycle of warm air
rising and cold air sinking, and
that's

315
00:22:12,260 --> 00:22:13,540
a convective cell.

316
00:22:16,500 --> 00:22:19,180
A plume of warm air rises,

317
00:22:19,180 --> 00:22:22,220
forms a cloud, cools, then sinks.

318
00:22:23,780 --> 00:22:26,300
And when you have many of these
convective clouds,

319
00:22:26,300 --> 00:22:29,660
an hexagonal pattern is produced
in the sky.

320
00:22:30,980 --> 00:22:34,620
So these clouds can only exist
when you have heating from below.

321
00:22:37,660 --> 00:22:41,100
Convection currents can happen
whenever hot meets cold.

322
00:22:42,940 --> 00:22:44,540
We see them in clouds.

323
00:22:46,860 --> 00:22:48,700
On the surface of the sun.

324
00:22:50,580 --> 00:22:52,500
And even in Mary's coffee.

325
00:22:55,740 --> 00:23:00,460
An understanding of how convection
currents work has led the scientists

326
00:23:00,460 --> 00:23:05,180
to realise that the soft nitrogen
ice on Pluto is slowly churning.

327
00:23:07,340 --> 00:23:10,380
We know that the convection rate
at least takes place over hundreds

328
00:23:10,380 --> 00:23:12,180
of thousands of Earth years.

329
00:23:12,180 --> 00:23:16,900
This is a slow process in terms
of human lifetime.

330
00:23:16,900 --> 00:23:20,620
It's a very quick process
in terms of geological time.

331
00:23:23,460 --> 00:23:27,700
The images sent back by New Horizons
show that fresh material

332
00:23:27,700 --> 00:23:32,500
is being brought to Pluto's surface
driven by convection currents.

333
00:23:34,540 --> 00:23:36,380
But convection needs heat.

334
00:23:40,660 --> 00:23:44,020
How could that be possible
on an ice world that's supposed

335
00:23:44,020 --> 00:23:45,380
to be frozen solid?

336
00:23:51,620 --> 00:23:56,300
The data returned from New Horizons
has forced us to rethink

337
00:23:56,300 --> 00:23:57,940
everything about Pluto.

338
00:24:00,140 --> 00:24:03,820
The surface of Pluto
has been repaved.

339
00:24:03,820 --> 00:24:07,020
The images are telling us
that there's some sort of geological

340
00:24:07,020 --> 00:24:08,460
processing going on.

341
00:24:09,500 --> 00:24:11,540
How could that be powered?

342
00:24:13,380 --> 00:24:17,780
On Earth, the heat that powers
geological activity doesn't come

343
00:24:17,780 --> 00:24:22,900
from the sun, but from radioactive
elements deep within Earth's mantle.

344
00:24:24,660 --> 00:24:28,300
Often when we think about
radioactive decay, we think

345
00:24:28,300 --> 00:24:31,340
about places like this, a nuclear
power plant.

346
00:24:32,500 --> 00:24:36,100
But there's a different kind of
radioactive decay

347
00:24:36,100 --> 00:24:39,940
that is constantly occurring
within heavy elements

348
00:24:39,940 --> 00:24:43,980
that are trapped within rocks,
rocks that make up planets.

349
00:24:45,660 --> 00:24:50,300
A tiny fraction of those radioactive
elements are harnessed as fuel

350
00:24:50,300 --> 00:24:52,940
for nuclear power stations
like this.

351
00:24:54,700 --> 00:24:58,940
But there's enough of them in
Earth's rocky interior

352
00:24:58,940 --> 00:25:02,540
to continually produce
44 trillion watts of power.

353
00:25:02,540 --> 00:25:04,340
RUMBLING

354
00:25:04,340 --> 00:25:07,740
And that power creates enormous
amounts of heat.

355
00:25:09,020 --> 00:25:14,460
Radioactive decay within the Earth
provides enough heat to produce

356
00:25:14,460 --> 00:25:16,620
all of the volcanoes that we see,

357
00:25:16,620 --> 00:25:20,620
the tectonic activity that leads
to the uplift of mountains...

358
00:25:21,860 --> 00:25:25,700
..the earthquakes and all of the

359
00:25:25,700 --> 00:25:29,780
geology that we see here
on planet Earth.

360
00:25:33,220 --> 00:25:38,500
Radioactive rock accounts for most
of the Earth's internal heat,

361
00:25:38,500 --> 00:25:43,300
heat which powers the geological
activity we see on the surface.

362
00:25:45,740 --> 00:25:50,460
But tiny Pluto, being mostly made
of ice, was thought to be different.

363
00:25:53,100 --> 00:25:55,900
Prior to the arrival of
New Horizons,

364
00:25:55,900 --> 00:26:01,220
the conventional wisdom was that
it's probably too small

365
00:26:01,220 --> 00:26:06,500
and too low in density to have
enough rock in its interior

366
00:26:06,500 --> 00:26:10,740
to drive enough radiogenic decay,
enough heating.

367
00:26:12,980 --> 00:26:17,460
But once New Horizons started
returning images and data

368
00:26:17,460 --> 00:26:19,500
about Pluto, that all changed.

369
00:26:22,540 --> 00:26:25,580
Could Pluto be heated from within
after all?

370
00:26:27,620 --> 00:26:29,980
The images sent back by New Horizons

371
00:26:29,980 --> 00:26:33,100
had allowed the scientists to see
Pluto's surface

372
00:26:33,100 --> 00:26:34,900
in unprecedented detail.

373
00:26:36,540 --> 00:26:39,020
Comparing multiple pictures allowed

374
00:26:39,020 --> 00:26:42,620
them to work out the height
of the mountains.

375
00:26:42,620 --> 00:26:44,420
And among them, Jeff spotted

376
00:26:44,420 --> 00:26:47,900
something that should be impossible
on a frozen world.

377
00:26:49,340 --> 00:26:51,980
We're looking at a large mountain,

378
00:26:51,980 --> 00:26:55,020
which is about 5km high,

379
00:26:55,020 --> 00:26:57,340
it's about 150km across,

380
00:26:57,340 --> 00:27:00,540
and in the centre is a large pit

381
00:27:00,540 --> 00:27:04,780
and the pit goes down to about the
same depth as the mountain is high.

382
00:27:04,780 --> 00:27:08,660
And when we first saw this we were
really surprised and puzzled

383
00:27:08,660 --> 00:27:10,180
as to what it might be.

384
00:27:10,180 --> 00:27:14,140
Nothing like this had ever been seen
on another world.

385
00:27:15,140 --> 00:27:18,380
And for Jeff, there was only
one explanation.

386
00:27:18,380 --> 00:27:19,900
A volcano.

387
00:27:21,860 --> 00:27:25,140
Its striking resemblance to a
volcano was so shocking

388
00:27:25,140 --> 00:27:27,900
that, in fact, I made the decision
not to discuss it

389
00:27:27,900 --> 00:27:29,540
in our initial press conference

390
00:27:29,540 --> 00:27:32,780
just because making such claims are
somewhat extraordinary

391
00:27:32,780 --> 00:27:35,940
and I didn't want to say anything
till we had more evidence.

392
00:27:35,940 --> 00:27:39,500
Once you see it as a volcano,
you can't unsee it.

393
00:27:41,780 --> 00:27:44,100
But a volcano didn't make sense.

394
00:27:45,220 --> 00:27:47,020
There is no lava on Pluto.

395
00:27:48,380 --> 00:27:50,700
A spectrograph on board the probe

396
00:27:50,700 --> 00:27:53,420
confirmed that Pluto
was made from ice.

397
00:27:54,940 --> 00:27:57,220
It has to be made of water ice.
Mm-hm.

398
00:27:57,220 --> 00:28:02,260
And water ice is the most difficult
thing to mobilise on Pluto.

399
00:28:02,260 --> 00:28:06,300
So it's a real challenge to imagine
how water ice could erupt

400
00:28:06,300 --> 00:28:07,980
under the surface the same way lava

401
00:28:07,980 --> 00:28:10,180
erupts up to the surface
on the Earth.

402
00:28:11,980 --> 00:28:16,260
The question was, how could ice
flow like lava

403
00:28:16,260 --> 00:28:20,580
on a world that's
230 degrees below zero?

404
00:28:27,740 --> 00:28:32,060
Space volcanologist Kelsi Singer
is on a mission.

405
00:28:32,060 --> 00:28:33,980
I would love to go to Pluto.

406
00:28:33,980 --> 00:28:36,420
Being able to stand on the surface

407
00:28:36,420 --> 00:28:41,260
and actually survey these features
like a geologist would be amazing.

408
00:28:43,820 --> 00:28:47,780
She wants to find out how
on a frozen world like Pluto,

409
00:28:47,780 --> 00:28:49,940
enormous volcanoes can exist.

410
00:28:52,060 --> 00:28:55,500
A lot of the landforms that you see,
like the mountains or the ice

411
00:28:55,500 --> 00:28:58,940
volcanoes, are probably mostly
made of water ice.

412
00:29:01,620 --> 00:29:04,180
The volcano on Pluto looks
remarkably similar

413
00:29:04,180 --> 00:29:05,700
to volcanoes on Earth...

414
00:29:07,020 --> 00:29:11,140
..where thick lava flows out over
huge areas to produce

415
00:29:11,140 --> 00:29:13,580
shallow mountain slopes.

416
00:29:13,580 --> 00:29:18,420
But Pluto is made from ice,
and ice doesn't behave like lava.

417
00:29:20,100 --> 00:29:23,980
If you have a feature that you think
formed from the flow of ice, that's

418
00:29:23,980 --> 00:29:27,140
very difficult to understand
how that would occur on Pluto.

419
00:29:29,460 --> 00:29:33,380
Pluto's surface is far too cold
for liquid water to flow

420
00:29:33,380 --> 00:29:34,700
over any distance.

421
00:29:36,380 --> 00:29:39,140
Instead, it would freeze
in an instant.

422
00:29:41,180 --> 00:29:44,260
I am in an ice castle in Colorado.

423
00:29:44,260 --> 00:29:47,460
It's about minus 12, so it's
pretty chilly.

424
00:29:47,460 --> 00:29:52,580
And how they form this is they have
sprinklers embedded in the ice.

425
00:29:52,580 --> 00:29:57,740
The water comes out at night and
then it freezes in these icicles.

426
00:29:57,740 --> 00:29:59,060
It's pretty cool!

427
00:30:01,900 --> 00:30:06,620
Temperatures here reach minus
20 degrees Celsius at night.

428
00:30:06,620 --> 00:30:09,780
Water from the sprinklers
freezes in seconds.

429
00:30:11,980 --> 00:30:15,740
And it looks nothing like
the volcano seen on Pluto.

430
00:30:18,580 --> 00:30:20,500
Hidden in New Horizons' images,

431
00:30:20,500 --> 00:30:23,860
Kelsi spotted the missing
ingredient.

432
00:30:23,860 --> 00:30:26,540
This fracture is called
Virgil Fossae.

433
00:30:26,540 --> 00:30:31,460
It's a couple of hundred kilometres
long and at least 5km high.

434
00:30:31,460 --> 00:30:33,740
And it's got a unique red colouring.

435
00:30:33,740 --> 00:30:37,860
And that red colouring turned out
to be associated with ammonia.

436
00:30:39,700 --> 00:30:43,180
The spectrograph on board
New Horizons had detected ammonia

437
00:30:43,180 --> 00:30:44,620
on Pluto's surface.

438
00:30:46,580 --> 00:30:51,260
The detection of ammonia on Pluto
was very important because it lowers

439
00:30:51,260 --> 00:30:53,740
the melting temperature of water.

440
00:30:55,580 --> 00:30:58,940
In fact, ammonia can lower
the freezing point of water

441
00:30:58,940 --> 00:31:01,020
by up to 100 degrees Celsius.

442
00:31:03,060 --> 00:31:07,060
I'm going to try to recreate the
effect of ammonia on Pluto's ice.

443
00:31:08,380 --> 00:31:11,580
But first, let's see what happens
with water just by itself.

444
00:31:14,020 --> 00:31:16,060
So I'm pouring out some water here.

445
00:31:18,540 --> 00:31:21,540
And then I'm going to add
the liquid nitrogen.

446
00:31:21,540 --> 00:31:24,620
At around minus 200 Celsius

447
00:31:24,620 --> 00:31:28,220
liquid nitrogen allows Kelsi
to simulate the extremely low

448
00:31:28,220 --> 00:31:30,620
temperatures on Pluto's surface.

449
00:31:31,580 --> 00:31:34,780
And we can see it's starting
to freeze here very quickly,

450
00:31:34,780 --> 00:31:37,180
turning into very cold ice.

451
00:31:41,660 --> 00:31:46,700
The ice on Pluto is about
minus 230 degrees Celsius.

452
00:31:46,700 --> 00:31:50,220
It acts more like rock
because it's so cold.

453
00:31:50,220 --> 00:31:54,420
Sort of like the ice that we have
recreated here.

454
00:31:54,420 --> 00:31:58,740
At this temperature water ice
is as hard as granite.

455
00:31:58,740 --> 00:32:01,220
This time we're going to try
adding ammonia.

456
00:32:01,220 --> 00:32:04,260
So here I have water and ammonia.

457
00:32:07,460 --> 00:32:10,220
And now I'm going to add
the liquid nitrogen.

458
00:32:12,980 --> 00:32:16,940
Ammonia lowers the freezing point
of water by physically blocking

459
00:32:16,940 --> 00:32:20,860
the water molecules, stopping them
from sticking together.

460
00:32:20,860 --> 00:32:22,260
Getting thicker.

461
00:32:26,340 --> 00:32:30,420
So now we have the water and ammonia
mixed together and it's forming

462
00:32:30,420 --> 00:32:33,460
a very thick and goopy,

463
00:32:33,460 --> 00:32:36,780
almost toothpaste-like fluid here,

464
00:32:36,780 --> 00:32:40,260
and we think that might be how
the volcanoes on Pluto formed,

465
00:32:40,260 --> 00:32:43,620
coming out from the subsurface
onto the surface

466
00:32:43,620 --> 00:32:46,260
and building up a volcano over time.

467
00:32:50,380 --> 00:32:54,580
Kelsi believes that this thick,
freezing liquid has erupted

468
00:32:54,580 --> 00:32:59,580
through Pluto's crust, flowed
across the surface like lava

469
00:32:59,580 --> 00:33:04,100
before freezing solid to form
the ice volcano that we see today.

470
00:33:06,380 --> 00:33:11,420
If you were standing on one
and watching a flow of icy lava,

471
00:33:11,420 --> 00:33:13,660
it would probably be actually quite

472
00:33:13,660 --> 00:33:16,180
slow going down the slope
of the volcano.

473
00:33:18,940 --> 00:33:22,860
Pluto has turned out to be
a geologically active world.

474
00:33:24,260 --> 00:33:27,260
Ice can flow like lava
thanks to ammonia.

475
00:33:29,580 --> 00:33:33,380
But volcanic eruptions still
need heat,

476
00:33:33,380 --> 00:33:37,420
and heat on icy Pluto would mean
something incredible.

477
00:33:39,460 --> 00:33:43,140
The fact that we see something
that could be an icy volcano,

478
00:33:43,140 --> 00:33:46,980
that had to form from flow
of material, means that the interior

479
00:33:46,980 --> 00:33:49,260
of Pluto must be somewhat warm.

480
00:33:49,260 --> 00:33:51,580
And that means that we could have

481
00:33:51,580 --> 00:33:54,500
a subsurface liquid water ocean
on Pluto.

482
00:33:56,540 --> 00:34:00,980
Liquid water has not been proven
to exist anywhere beyond Earth.

483
00:34:02,500 --> 00:34:08,900
This small, unassuming little world
may actually have a liquid water

484
00:34:08,900 --> 00:34:11,620
ocean beneath its icy surface.

485
00:34:12,820 --> 00:34:16,420
And the evidence from the
New Horizons mission...

486
00:34:18,300 --> 00:34:24,340
..makes it quite hard to explain
what we're seeing without invoking

487
00:34:24,340 --> 00:34:26,780
an ocean as an explanation.

488
00:34:29,660 --> 00:34:34,220
The realisation that this icy world
could be hiding a liquid ocean

489
00:34:34,220 --> 00:34:38,180
has forced scientists to rethink
everything about Pluto.

490
00:34:39,980 --> 00:34:42,420
But there was a mystery.

491
00:34:42,420 --> 00:34:44,900
Pluto's size.

492
00:34:44,900 --> 00:34:49,620
The problem with Pluto in terms of
its heat from the interior

493
00:34:49,620 --> 00:34:53,580
is that it probably doesn't have
enough of the raw materials.

494
00:34:53,580 --> 00:34:59,500
Uh, there's not enough radiogenic
decay to keep it warm from within

495
00:34:59,500 --> 00:35:02,540
for a very long period of time.

496
00:35:02,540 --> 00:35:05,420
And yet the evidence is that
something is driving

497
00:35:05,420 --> 00:35:10,060
this geological processing, so there
must be another piece of the puzzle.

498
00:35:10,060 --> 00:35:14,700
There must be something else
on or within Pluto that is helping

499
00:35:14,700 --> 00:35:19,820
it retain the small amount of heat
that it gets from the interior,

500
00:35:19,820 --> 00:35:21,460
from radiogenic decay.

501
00:35:24,220 --> 00:35:28,140
A small amount of radioactive rock
in tiny Pluto's core

502
00:35:28,140 --> 00:35:29,780
may provide some heat.

503
00:35:31,180 --> 00:35:35,180
But for Pluto to hang on to it,
something must be keeping it in.

504
00:35:38,700 --> 00:35:43,700
And this could be down to a special
type of snow called a gas hydrate.

505
00:35:48,420 --> 00:35:52,540
Scientists at the National
Oceanography Centre in Southampton

506
00:35:52,540 --> 00:35:54,060
make it in their lab.

507
00:35:57,820 --> 00:35:59,820
It looks like ordinary snow.

508
00:36:01,060 --> 00:36:03,500
It's freezing cold, like
ordinary snow.

509
00:36:03,500 --> 00:36:05,100
MATCH STRIKES

510
00:36:05,100 --> 00:36:09,140
But take a match to it and it
immediately bursts into flames.

511
00:36:14,700 --> 00:36:18,740
This, in my hand, looks like ice,
but it is actually burning.

512
00:36:19,940 --> 00:36:23,580
And that flame is actually
methane gas that's been coming off

513
00:36:23,580 --> 00:36:25,420
the ice as it melts.

514
00:36:28,300 --> 00:36:32,180
It burns because flammable gas,
like methane, gets trapped

515
00:36:32,180 --> 00:36:34,820
within the crystal structure of ice.

516
00:36:36,780 --> 00:36:42,060
Gas hydrates form naturally on Earth
under very particular conditions.

517
00:36:42,060 --> 00:36:45,820
It occurs in very large quantities
in places like the Arctic.

518
00:36:45,820 --> 00:36:47,500
And, in fact, in the Antarctic as
well.

519
00:36:47,500 --> 00:36:49,660
So both polar regions where
it's very cold.

520
00:36:51,860 --> 00:36:56,460
Huge amounts of gas hydrates exist
in the very coldest places on Earth,

521
00:36:56,460 --> 00:36:58,940
especially where methane is present.

522
00:37:03,020 --> 00:37:06,620
The same conditions that produce
gas hydrates on Earth also

523
00:37:06,620 --> 00:37:08,260
exist on Pluto.

524
00:37:10,100 --> 00:37:13,340
So it's possible that they form
on Pluto, too.

525
00:37:14,980 --> 00:37:17,340
In order to explain what we see
on Pluto's surface,

526
00:37:17,340 --> 00:37:18,860
we really do need heat.

527
00:37:18,860 --> 00:37:22,900
We see activity currently going on,
which was exciting and unexpected

528
00:37:22,900 --> 00:37:24,940
and wonderful, but now it

529
00:37:24,940 --> 00:37:27,780
comes down to the science of
explaining it.

530
00:37:30,540 --> 00:37:34,860
Dr Carly Howett designed the cameras
on the New Horizons probe.

531
00:37:36,460 --> 00:37:40,380
She believes that it's the hydrates'
ability to trap gas

532
00:37:40,380 --> 00:37:43,220
that could be the answer
to Pluto's heat problem.

533
00:37:49,740 --> 00:37:53,340
The water ice forms a hexagon
almost like a cage.

534
00:37:53,340 --> 00:37:55,220
And then inside is gas.

535
00:37:55,220 --> 00:37:57,060
In this case, we think it's
probably methane.

536
00:37:58,660 --> 00:38:00,100
These are incredibly small.

537
00:38:00,100 --> 00:38:03,340
You'd end up with millions
upon millions of very,

538
00:38:03,340 --> 00:38:07,980
very small cages, each holding
its own little methane gas bubble.

539
00:38:09,500 --> 00:38:13,780
The gas bubbles on Pluto don't
ignite, but act like a thermal

540
00:38:13,780 --> 00:38:16,340
insulator, trapping heat.

541
00:38:16,340 --> 00:38:20,020
This gas hydrate is very insulating
and it could be kind of forming

542
00:38:20,020 --> 00:38:24,060
a warm blanket that's enabling
Pluto to hold its heat in,

543
00:38:24,060 --> 00:38:27,700
enabling Pluto to remain warm
for billions of years.

544
00:38:29,980 --> 00:38:34,820
Pluto's surface temperature
is a frigid 230 degrees below zero.

545
00:38:37,340 --> 00:38:41,300
And scientists now believe
that a thick layer of gas hydrate

546
00:38:41,300 --> 00:38:45,580
snow could be insulating Pluto's
warm radioactive rock

547
00:38:45,580 --> 00:38:48,500
from those freezing surface
temperatures.

548
00:38:49,660 --> 00:38:52,460
Keeping in enough heat
to melt the ice.

549
00:38:56,900 --> 00:39:00,100
So the heat comes from the rocky
core and it can't escape

550
00:39:00,100 --> 00:39:02,660
through this insulating layer
and maybe it's warm enough

551
00:39:02,660 --> 00:39:05,380
so that you end up being able
to sustain liquid water, form

552
00:39:05,380 --> 00:39:09,060
and sustain liquid water, and maybe
even in the form of a sort of

553
00:39:09,060 --> 00:39:10,780
global ocean, which is incredible.

554
00:39:10,780 --> 00:39:12,940
Pluto is a long way from the sun.

555
00:39:14,020 --> 00:39:16,460
That amount of heat is unexpected.

556
00:39:18,260 --> 00:39:22,740
The scientists had found a way that
liquid water could exist on Pluto.

557
00:39:24,620 --> 00:39:28,060
Everything they thought about this
icy world had been turned

558
00:39:28,060 --> 00:39:32,820
on its head, which has led some
scientists to think the impossible.

559
00:39:35,740 --> 00:39:39,620
So if Pluto is warm enough
to sustain a liquid water ocean,

560
00:39:39,620 --> 00:39:42,140
this has huge implications
for astrobiology.

561
00:39:42,140 --> 00:39:45,500
One of the things that we know
about life is it likes liquid water.

562
00:39:47,300 --> 00:39:49,140
Liquid water is one of the

563
00:39:49,140 --> 00:39:52,500
requirements for having life,
as far as we know.

564
00:39:52,500 --> 00:39:57,060
And so if we were to find a
subsurface liquid ocean on Pluto,

565
00:39:57,060 --> 00:39:59,460
that would give us more reason
to believe that there could

566
00:39:59,460 --> 00:40:03,180
potentially have been in the past
or even currently be some kind

567
00:40:03,180 --> 00:40:05,620
of life forms in the ocean on
Pluto.

568
00:40:08,780 --> 00:40:11,500
If we've learned anything from our
study of life on Earth,

569
00:40:11,500 --> 00:40:15,140
it's that where you find liquid
water, you generally find life.

570
00:40:15,140 --> 00:40:19,220
We look for liquid water as the
sort of

571
00:40:19,220 --> 00:40:21,860
canary in the coal mine
for habitability.

572
00:40:21,860 --> 00:40:26,260
If you've got liquid water,
perhaps you could also harbour life.

573
00:40:29,380 --> 00:40:34,020
On Earth, almost everywhere you find
liquid water, you find life.

574
00:40:36,820 --> 00:40:40,340
And the new pictures of Pluto seemed
to suggest that it was hiding

575
00:40:40,340 --> 00:40:42,180
a vast underground ocean.

576
00:40:45,380 --> 00:40:49,140
Pluto had been propelled from being
an icy relic to a place

577
00:40:49,140 --> 00:40:51,340
where alien life could exist.

578
00:40:53,540 --> 00:40:56,180
But there was still something
missing,

579
00:40:56,180 --> 00:40:58,300
if biology was to have any hope.

580
00:41:01,060 --> 00:41:03,540
As well as heat and liquid water,

581
00:41:03,540 --> 00:41:06,540
life requires a complex array
of chemical ingredients.

582
00:41:08,140 --> 00:41:10,420
Could they exist on tiny Pluto?

583
00:41:16,900 --> 00:41:21,020
The first clue about Pluto's
chemistry came in 1988,

584
00:41:21,020 --> 00:41:22,900
long before New Horizons...

585
00:41:24,540 --> 00:41:28,140
..when images like this were
all that scientists had.

586
00:41:29,620 --> 00:41:31,540
So here is a picture you can take

587
00:41:31,540 --> 00:41:35,180
from the ground-based telescope
like this.

588
00:41:35,180 --> 00:41:38,460
And there are a lot of beautiful
background stars here,

589
00:41:38,460 --> 00:41:43,140
but there's one particular
important one we are talking about

590
00:41:43,140 --> 00:41:46,780
today, is Pluto here, in the middle
of this picture.

591
00:41:46,780 --> 00:41:49,820
It's not much, right?
It's only a few pixels.

592
00:41:51,900 --> 00:41:56,100
From Earth, Pluto was nothing
but a tiny white dot.

593
00:41:56,100 --> 00:42:00,580
So astronomers waited for a rare
event called an occultation.

594
00:42:01,620 --> 00:42:04,220
So, look at those background
stars here,

595
00:42:04,220 --> 00:42:06,460
they are relatively stationary,

596
00:42:06,460 --> 00:42:08,340
but Pluto is moving in the sky.

597
00:42:11,540 --> 00:42:15,180
As Pluto passed in front
of a background star,

598
00:42:15,180 --> 00:42:18,460
rather than blocking the starlight
abruptly, the starlight

599
00:42:18,460 --> 00:42:19,780
was slowly dimmed.

600
00:42:23,260 --> 00:42:25,420
This could only mean one thing.

601
00:42:28,820 --> 00:42:31,020
That Pluto had an atmosphere.

602
00:42:32,700 --> 00:42:33,980
Here dry ice.

603
00:42:37,340 --> 00:42:39,380
OK. Look at this atmosphere

604
00:42:39,380 --> 00:42:41,780
we just made in the laboratory.

605
00:42:41,780 --> 00:42:45,300
And if there is a light source
behind it, the light source will

606
00:42:45,300 --> 00:42:50,980
get dimmed because of the absorption
and a scattering of the atmosphere.

607
00:42:50,980 --> 00:42:55,020
And that's similar to what happens
in Pluto's occultation.

608
00:42:57,020 --> 00:43:01,700
Here, dry ice vapour scatters
the torchlight in the same way

609
00:43:01,700 --> 00:43:04,260
that Pluto scattered the starlight.

610
00:43:05,460 --> 00:43:08,500
It was proof that Pluto
had an atmosphere.

611
00:43:10,260 --> 00:43:12,780
This was a complete surprise,

612
00:43:12,780 --> 00:43:17,380
a tantalising clue that Pluto
was much more than a frozen relic.

613
00:43:18,780 --> 00:43:21,620
But the question remained,
what was Pluto's

614
00:43:21,620 --> 00:43:23,060
atmosphere made from?

615
00:43:24,420 --> 00:43:27,500
The New Horizons probe was sent
to find out.

616
00:43:28,860 --> 00:43:32,820
And when it returned this picture,
the scientists were able to see

617
00:43:32,820 --> 00:43:36,300
the atmosphere in detail
for the very first time.

618
00:43:38,700 --> 00:43:40,940
This is such a beautiful image.

619
00:43:40,940 --> 00:43:46,020
You look at this and you think
blue skies, just like Earth.

620
00:43:46,020 --> 00:43:50,860
This image says we were really there
because this is the kind of image

621
00:43:50,860 --> 00:43:54,740
you can only get after you pass
by Pluto.

622
00:43:54,740 --> 00:43:58,740
This picture was taken looking back
toward the sun and Earth,

623
00:43:58,740 --> 00:44:02,620
and we're seeing Pluto backlit
by the sun.

624
00:44:05,700 --> 00:44:10,020
The onboard spectrograph revealed
that Pluto's atmosphere was made

625
00:44:10,020 --> 00:44:13,020
mostly of nitrogen gas,
just like Earth.

626
00:44:16,260 --> 00:44:20,580
As New Horizons continued away
from Pluto, the long-range camera

627
00:44:20,580 --> 00:44:23,820
took one of the most important
photographs of the entire mission.

628
00:44:26,020 --> 00:44:29,740
And it contained something that the
scientists did not predict.

629
00:44:30,940 --> 00:44:34,540
Like everybody, I was surprised
at this beautiful structured

630
00:44:34,540 --> 00:44:38,020
atmosphere, all these layers
were wholly unexpected.

631
00:44:38,020 --> 00:44:41,900
There is so much going on in this
picture.

632
00:44:41,900 --> 00:44:47,380
We can actually see these layers
in the haze in Pluto's atmosphere.

633
00:44:47,380 --> 00:44:51,580
They're about 20km or so between
each one and we see

634
00:44:51,580 --> 00:44:55,660
the haze going up for 200km
or more in this image.

635
00:44:57,100 --> 00:45:01,540
The layers in Pluto's atmosphere
were a complete mystery.

636
00:45:04,420 --> 00:45:08,420
Invisible nitrogen gas alone
couldn't explain the layers.

637
00:45:11,140 --> 00:45:16,860
Planetary scientist Xi Zhang thinks
it could be caused by sunlight,

638
00:45:16,860 --> 00:45:18,940
because even on distant Pluto,

639
00:45:18,940 --> 00:45:23,220
ultraviolet rays have a profound
effect on atmospheric gases.

640
00:45:24,940 --> 00:45:27,980
It happens every day on Earth
and can even be seen

641
00:45:27,980 --> 00:45:29,900
above downtown Los Angeles.

642
00:45:31,660 --> 00:45:34,820
You can see the air quality
is not good.

643
00:45:34,820 --> 00:45:36,660
Smogs, hazes.

644
00:45:37,940 --> 00:45:43,700
That's because we have three million
cars crisscross the city every day

645
00:45:43,700 --> 00:45:47,940
and those cars emit a lot
of air pollution.

646
00:45:49,340 --> 00:45:52,860
The air pollution is mostly
volatile organic compounds

647
00:45:52,860 --> 00:45:55,540
like hydrocarbons, soot particles.

648
00:45:57,100 --> 00:46:01,300
Large soot particles hang
in the air above the city.

649
00:46:01,300 --> 00:46:05,060
They're created by a
chemical reaction.

650
00:46:05,060 --> 00:46:09,220
Exhaust fumes from cars are baked
by the sun, causing them to

651
00:46:09,220 --> 00:46:12,260
break down and re-form into larger
particles.

652
00:46:14,260 --> 00:46:17,940
Those smogs are actually pretty
similar to what we see on Pluto

653
00:46:17,940 --> 00:46:20,180
in terms of chemical processes.

654
00:46:22,180 --> 00:46:24,900
But there are no cars on Pluto,

655
00:46:24,900 --> 00:46:29,460
so why is its atmosphere
choking with smog?

656
00:46:29,460 --> 00:46:33,900
When New Horizons analysed Pluto's
atmosphere, it discovered

657
00:46:33,900 --> 00:46:35,820
that it wasn't just made
from nitrogen.

658
00:46:37,060 --> 00:46:41,100
There were also tiny amounts
of other gases like methane

659
00:46:41,100 --> 00:46:42,500
and carbon monoxide.

660
00:46:44,060 --> 00:46:49,020
When those air molecules hit
by the UV light from the sun,

661
00:46:49,020 --> 00:46:52,900
the chemical bonds are broken
and those coagulate to make big

662
00:46:52,900 --> 00:46:57,140
particles, it's similar to the
soot particles we have here.

663
00:47:00,180 --> 00:47:04,620
Just like the exhaust fumes
above Los Angeles, the invisible gas

664
00:47:04,620 --> 00:47:09,340
molecules in Pluto's atmosphere were
being broken apart by the sun...

665
00:47:10,580 --> 00:47:13,740
..before re-forming into large
soot particles

666
00:47:13,740 --> 00:47:15,900
and settling out into layers.

667
00:47:17,780 --> 00:47:21,700
Those haze particles are produced
in the upper atmosphere of Pluto

668
00:47:21,700 --> 00:47:24,780
and gradually settle down due
to gravity.

669
00:47:28,860 --> 00:47:30,580
The soot particles were a clue

670
00:47:30,580 --> 00:47:33,100
that something special was happening
on Pluto.

671
00:47:35,660 --> 00:47:39,020
But exactly what chemicals were
being created?

672
00:47:39,020 --> 00:47:42,060
Ready? High voltage down.

673
00:47:42,060 --> 00:47:47,300
The probe had told scientists what
gases exist in Pluto's atmosphere.

674
00:47:47,300 --> 00:47:48,740
The MSCs are off.

675
00:47:48,740 --> 00:47:52,180
Which allowed them to do something
that had never been done before.

676
00:47:52,180 --> 00:47:54,460
Cylinders are closed.

677
00:47:54,460 --> 00:47:57,460
Recreate Pluto's atmosphere
here on Earth.

678
00:47:59,340 --> 00:48:03,780
What this machine allows to do
is to simulate space environment.

679
00:48:03,780 --> 00:48:08,020
In the case of Pluto, we can
simulate the atmosphere of Pluto.

680
00:48:08,020 --> 00:48:09,180
OK?

681
00:48:09,180 --> 00:48:11,580
Doing this experiment will allow us

682
00:48:11,580 --> 00:48:13,660
to get a better idea of the type

683
00:48:13,660 --> 00:48:17,260
of chemical processes that are
occurring in the atmosphere.

684
00:48:17,260 --> 00:48:19,420
Pressure, eight torr.

685
00:48:19,420 --> 00:48:21,460
Yeah, that's the base pressure,
that's good.

686
00:48:21,460 --> 00:48:23,860
The base pressure is eight so
it's very good.

687
00:48:23,860 --> 00:48:27,140
Pluto's atmospheric gases
enter this machine

688
00:48:27,140 --> 00:48:29,780
at minus 170 degrees centigrade...

689
00:48:31,740 --> 00:48:35,620
..where an electrical discharge
simulates the sun's rays.

690
00:48:38,300 --> 00:48:41,940
After ten hours in the machine,
the gases are transformed

691
00:48:41,940 --> 00:48:44,180
into an entirely new substance.

692
00:48:45,820 --> 00:48:47,260
Tiny grains of dust.

693
00:48:49,020 --> 00:48:54,300
These are these grains that we make
in the gas and that get deposited

694
00:48:54,300 --> 00:48:58,420
onto a window and piled on top
of each other until we have a thin

695
00:48:58,420 --> 00:49:01,860
layer of these dust grains.

696
00:49:01,860 --> 00:49:05,140
And, as you can see, the colour
is a dark brown.

697
00:49:08,580 --> 00:49:11,020
These are the same particles
that cause the layers

698
00:49:11,020 --> 00:49:12,620
in Pluto's atmosphere.

699
00:49:15,340 --> 00:49:19,060
Eventually they grow so big
that they fall to the surface

700
00:49:19,060 --> 00:49:25,420
like rain, painting Pluto in a broad
spectrum of browns and reds.

701
00:49:25,420 --> 00:49:27,700
So we can think that this could be

702
00:49:27,700 --> 00:49:31,100
one of the contributions
for the colour on Pluto's surface.

703
00:49:35,140 --> 00:49:38,300
A chemical reaction in Pluto's
atmosphere was causing

704
00:49:38,300 --> 00:49:41,100
particles to rain down onto
the surface.

705
00:49:44,220 --> 00:49:48,180
So this is an enhanced colour image
and we can see that this area

706
00:49:48,180 --> 00:49:50,460
is really red and quite dark,

707
00:49:50,460 --> 00:49:54,060
and much redder than the rest
of Pluto's surface.

708
00:49:56,500 --> 00:50:01,220
Areas that receive more sunlight
appear much redder than elsewhere.

709
00:50:03,820 --> 00:50:07,300
The next job for the scientists
was to find out exactly

710
00:50:07,300 --> 00:50:09,380
what this red substance was.

711
00:50:15,620 --> 00:50:20,060
Dale Cruikshank studies the surface
of small objects in space.

712
00:50:23,740 --> 00:50:26,380
And since New Horizons,
he has turned his attention

713
00:50:26,380 --> 00:50:29,620
to the chemical reactions
occurring on Pluto.

714
00:50:34,100 --> 00:50:37,140
Pluto has a very thin atmosphere,
and we know that the basic

715
00:50:37,140 --> 00:50:40,980
components are nitrogen,
methane and carbon monoxide.

716
00:50:44,780 --> 00:50:48,340
Sunlight coming in, in the
ultraviolet part of the spectrum,

717
00:50:48,340 --> 00:50:51,140
has enough energy to break the
energetic bonds

718
00:50:51,140 --> 00:50:54,780
that hold the atoms in the
molecules together.

719
00:50:54,780 --> 00:51:00,180
These simple gases re-form randomly
into more complex molecules.

720
00:51:00,180 --> 00:51:02,180
Like that.

721
00:51:02,180 --> 00:51:04,580
And experiments to recreate this

722
00:51:04,580 --> 00:51:07,580
have produced something
extraordinary.

723
00:51:07,580 --> 00:51:11,500
Eventually, these materials form
what we call precursor molecules

724
00:51:11,500 --> 00:51:16,220
to molecules that are of biological
interest,

725
00:51:16,220 --> 00:51:20,020
including what are called
nucleobases.

726
00:51:20,020 --> 00:51:23,140
There are many different
nucleobases, but five of them

727
00:51:23,140 --> 00:51:26,700
are of biological interest
because these are the principal

728
00:51:26,700 --> 00:51:29,340
components of DNA and RNA.

729
00:51:32,380 --> 00:51:35,700
Nucleobases are the main ingredient
of DNA.

730
00:51:37,220 --> 00:51:40,900
All life on Earth uses DNA.

731
00:51:40,900 --> 00:51:43,460
From these complex molecules

732
00:51:43,460 --> 00:51:45,580
life is just a few steps away.

733
00:51:46,900 --> 00:51:49,980
And some scientists believe
it's possible

734
00:51:49,980 --> 00:51:52,540
that they're being produced
on Pluto.

735
00:51:53,940 --> 00:51:57,580
The New Horizons mission has given
us these fantastic images

736
00:51:57,580 --> 00:52:00,540
from which we now deduce
that the colours are in fact

737
00:52:00,540 --> 00:52:04,420
from organic material,
complex organics that have fallen

738
00:52:04,420 --> 00:52:06,100
from the sky, literally.

739
00:52:07,340 --> 00:52:12,020
We are making precursors to the
things that eventually

740
00:52:12,020 --> 00:52:15,460
we think on Earth resulted
in the origin of life.

741
00:52:17,900 --> 00:52:22,220
And the surface isn't the only place
where pre-life organic molecules

742
00:52:22,220 --> 00:52:23,780
could be being made.

743
00:52:26,100 --> 00:52:29,860
Complex organics are also
being produced in water

744
00:52:29,860 --> 00:52:34,620
and have emerged onto the surface
through cracks in the crust

745
00:52:34,620 --> 00:52:37,580
in a process that we call
cryovolcanism.

746
00:52:39,460 --> 00:52:43,700
The red colour of the ice around
Virgil Fossae is evidence, not

747
00:52:43,700 --> 00:52:48,140
only of ammonia, but also
organic material erupting

748
00:52:48,140 --> 00:52:49,860
from an underground sea.

749
00:52:51,540 --> 00:52:54,220
There may be habitable zones
on Pluto.

750
00:52:54,220 --> 00:52:56,940
For example, in the interior,
if there is still a liquid

751
00:52:56,940 --> 00:52:59,540
and it's full of organic materials,

752
00:52:59,540 --> 00:53:02,660
this may be a habitat where life
could exist.

753
00:53:04,300 --> 00:53:09,700
So, if we were trying to survey the
entire solar system for potential

754
00:53:09,700 --> 00:53:11,500
habitable zones, habitable regions,

755
00:53:11,500 --> 00:53:14,460
you'd have to include Pluto
in that list, I think.

756
00:53:16,180 --> 00:53:20,620
The complexities of just how organic
molecules spawn life is not

757
00:53:20,620 --> 00:53:22,060
yet fully understood.

758
00:53:23,740 --> 00:53:28,140
But Dale's experiments are evidence
that Pluto has the raw ingredients

759
00:53:28,140 --> 00:53:31,700
to produce some of the molecules
needed for life.

760
00:53:33,660 --> 00:53:38,140
Within Pluto, you might have liquid
water, mixed with ammonia, mixed

761
00:53:38,140 --> 00:53:41,980
with methane and any number
of different kinds of organic

762
00:53:41,980 --> 00:53:46,060
compounds, carbon compounds
that life could utilise.

763
00:53:46,060 --> 00:53:50,500
And so along with Pluto potentially
having this liquid water environment

764
00:53:50,500 --> 00:53:53,940
that could be conducive for life,

765
00:53:53,940 --> 00:53:58,820
it might have some of the elements
and energy that life

766
00:53:58,820 --> 00:54:00,780
as we know it needs.

767
00:54:04,140 --> 00:54:06,660
No-one in their right mind
would have thought Pluto had life,

768
00:54:06,660 --> 00:54:09,380
but now it's a possibility
and that in itself is kind

769
00:54:09,380 --> 00:54:10,380
of mind-blowing.

770
00:54:12,060 --> 00:54:15,140
What might life on Pluto look like?

771
00:54:15,140 --> 00:54:21,380
Who knows? But...I would be happy
with even the tiniest of

772
00:54:21,380 --> 00:54:23,620
single-celled microbial organism

773
00:54:23,620 --> 00:54:26,500
somewhere out there in our
solar system and beyond.

774
00:54:30,340 --> 00:54:34,580
And if on Pluto,
the most unlikely of places,

775
00:54:34,580 --> 00:54:36,340
then why not elsewhere?

776
00:54:37,700 --> 00:54:40,900
We used to think that life could
only exist on a planet like Earth,

777
00:54:40,900 --> 00:54:42,900
with ocean on the outside,
an atmosphere,

778
00:54:42,900 --> 00:54:44,740
sunlight falling in and so on.

779
00:54:46,700 --> 00:54:48,500
Now we learned there are liquid

780
00:54:48,500 --> 00:54:50,660
oceans elsewhere in the
solar system.

781
00:54:50,660 --> 00:54:53,180
They are around Jupiter,
they are inside Pluto.

782
00:54:53,180 --> 00:54:55,700
And it changes our concept
of what the Goldilocks Zone is,

783
00:54:55,700 --> 00:54:58,180
the zone in which life could
potentially form.

784
00:55:00,180 --> 00:55:03,900
If places like Pluto, really small,
very distant from a star,

785
00:55:03,900 --> 00:55:06,220
are able to have liquid water,

786
00:55:06,220 --> 00:55:08,860
it could mean that Pluto
maybe has life.

787
00:55:08,860 --> 00:55:12,380
But also, as we move into other
solar systems and we understand

788
00:55:12,380 --> 00:55:13,980
more about other solar systems,

789
00:55:13,980 --> 00:55:17,060
maybe life could be more abundant
than we thought.

790
00:55:18,900 --> 00:55:22,660
My view is that the chemistry
of life, in so far as we understand

791
00:55:22,660 --> 00:55:26,900
it, is so widespread through
the solar system, through our galaxy

792
00:55:26,900 --> 00:55:29,020
and elsewhere in the universe,

793
00:55:29,020 --> 00:55:35,100
that it is highly likely that
self-replicating metabolising

794
00:55:35,100 --> 00:55:37,380
entities have originated.

795
00:55:37,380 --> 00:55:40,820
And if that's life, then the answer
is yes, there is life elsewhere.

796
00:55:46,500 --> 00:55:49,580
Long viewed as a world of
little importance...

797
00:55:52,820 --> 00:55:55,220
..Pluto has been revealed
to be a place

798
00:55:55,220 --> 00:55:57,220
of unimaginable complexity.

799
00:56:00,940 --> 00:56:02,980
Mountains carved from ice...

800
00:56:04,980 --> 00:56:08,020
..rival the most dramatic
landscapes on Earth.

801
00:56:11,900 --> 00:56:15,860
A frozen volcano like nothing else
in the solar system.

802
00:56:21,020 --> 00:56:25,300
A churning nitrogen glacier puzzles
science's greatest minds.

803
00:56:29,660 --> 00:56:34,140
It's a place where something,
extraterrestrial life, might exist.

804
00:56:39,540 --> 00:56:42,820
And could tell us where else
in the universe we might find it.

805
00:56:47,460 --> 00:56:52,020
This great mystery on the very edge
of our solar system has led

806
00:56:52,020 --> 00:56:54,740
scientists to call for another
mission.

807
00:56:56,220 --> 00:56:59,100
The only way to really study
the surface of Pluto in detail

808
00:56:59,100 --> 00:57:00,660
is to go back to Pluto.

809
00:57:00,660 --> 00:57:05,100
And that's why I'm leading a concept
study to figure out how we would

810
00:57:05,100 --> 00:57:06,300
go about doing that.

811
00:57:08,100 --> 00:57:09,940
They plan to send another probe.

812
00:57:11,260 --> 00:57:14,340
We need another mission
to go back to Pluto,

813
00:57:14,340 --> 00:57:16,300
and this time orbit Pluto.

814
00:57:16,300 --> 00:57:18,420
And we can bring different
instruments that can get

815
00:57:18,420 --> 00:57:19,940
us different answers.

816
00:57:21,980 --> 00:57:24,660
And peer beneath Pluto's icy crust.

817
00:57:27,620 --> 00:57:31,340
If we committed ourselves
to exploring these ocean worlds,

818
00:57:31,340 --> 00:57:36,460
it could be that within the next few
decades we might finally

819
00:57:36,460 --> 00:57:42,060
have an answer to that primordial
age-old question of whether or not

820
00:57:42,060 --> 00:57:44,220
we are alone in the universe.

821
00:57:46,340 --> 00:57:49,940
To the Romans, Pluto was the
god of the afterlife.

822
00:57:51,180 --> 00:57:53,860
But this tiny dwarf planet may,

823
00:57:53,860 --> 00:57:57,300
in fact, be the gatekeeper
to life itself.

824
00:58:03,100 --> 00:58:06,940
Pluto is well and truly
back from the dead.