1
00:00:00,768 --> 00:00:03,502
♪
2
00:00:03,504 --> 00:00:07,406
narrator: Earth --
a planet defined by life.
3
00:00:07,408 --> 00:00:10,109
Stricker: The amazing thing
about life here on earth
4
00:00:10,111 --> 00:00:13,579
is no matter where you look,
you'll find it.
5
00:00:13,581 --> 00:00:15,447
Narrator: But is earth unique?
6
00:00:15,449 --> 00:00:17,282
Thaller:
The big question of our day is,
7
00:00:17,284 --> 00:00:20,586
does life exist somewhere else
beside the earth?
8
00:00:20,588 --> 00:00:24,056
Are we that special,
or is life everywhere?
9
00:00:24,058 --> 00:00:25,891
Narrator:
The ingredients for life
10
00:00:25,893 --> 00:00:27,760
are spread throughout
the universe.
11
00:00:27,762 --> 00:00:29,895
But then we started looking
into space and saying,
12
00:00:29,897 --> 00:00:33,032
"wait a second.
That chemistry is everywhere."
13
00:00:35,169 --> 00:00:37,903
narrator:
Is life inevitable?
14
00:00:37,905 --> 00:00:40,706
I think that there have to be
planets out there
15
00:00:40,708 --> 00:00:44,243
that are capable
of hosting life.
16
00:00:44,245 --> 00:00:47,846
Narrator: What does life need
to get started,
17
00:00:47,848 --> 00:00:51,917
and once started,
can life spread?
18
00:00:51,919 --> 00:00:55,854
It's possible that life
started on mars
19
00:00:55,856 --> 00:01:00,426
and was transferred to earth
inside of a meteorite.
20
00:01:00,428 --> 00:01:02,528
Narrator:
Life has conquered our planet,
21
00:01:02,530 --> 00:01:06,131
but can life conquer
the universe?
22
00:01:06,133 --> 00:01:13,872
♪
23
00:01:13,874 --> 00:01:16,875
-- captions by vitac --
www.Vitac.Com
24
00:01:16,877 --> 00:01:19,878
captions paid for by
discovery communications
25
00:01:19,880 --> 00:01:22,548
♪
26
00:01:22,550 --> 00:01:26,518
the universe
is a very big place.
27
00:01:26,520 --> 00:01:29,855
There are trillions of galaxies,
28
00:01:29,857 --> 00:01:33,759
each one home
to millions of stars
29
00:01:33,761 --> 00:01:37,830
and an unimaginable number
of planets.
30
00:01:37,832 --> 00:01:40,065
So where is everybody?
31
00:01:40,067 --> 00:01:43,168
One of the most basic
philosophical questions is,
32
00:01:43,170 --> 00:01:44,703
are we alone?
33
00:01:44,705 --> 00:01:47,306
Are we the only ones
looking out and thinking,
34
00:01:47,308 --> 00:01:48,974
"what is all this?"
35
00:01:48,976 --> 00:01:54,079
is it all just for us, or do
we get to share it with anyone?
36
00:01:54,081 --> 00:01:56,381
I mean, that's about
as fundamental a question
37
00:01:56,383 --> 00:01:58,951
as you get.
38
00:01:58,953 --> 00:02:02,354
Narrator: What are the odds of
life existing somewhere else?
39
00:02:04,425 --> 00:02:07,059
We just don't have a good
insight
40
00:02:07,061 --> 00:02:11,497
to how probable life
is anywhere in the universe.
41
00:02:11,499 --> 00:02:13,665
Life could possibly
be forming everywhere.
42
00:02:13,667 --> 00:02:15,234
We don't quite know.
43
00:02:15,236 --> 00:02:19,938
There's a lot about life
that we don't understand.
44
00:02:19,940 --> 00:02:24,510
All we know is that
it happened at least once.
45
00:02:24,512 --> 00:02:26,745
But beyond this
one little planet,
46
00:02:26,747 --> 00:02:29,481
we don't know whether or not
it happened anywhere else.
47
00:02:29,483 --> 00:02:34,019
♪
48
00:02:34,021 --> 00:02:36,421
narrator: The universe is
an unfriendly place.
49
00:02:39,426 --> 00:02:44,830
Planets with lava oceans
circle too close to their stars.
50
00:02:44,832 --> 00:02:50,435
Pulsars blaze with
deadly gamma rays and x-rays.
51
00:02:50,437 --> 00:02:54,106
Black holes consume
everything in their path.
52
00:02:54,108 --> 00:02:57,876
Temperatures plummet close
to absolute zero.
53
00:02:57,878 --> 00:03:02,414
♪
54
00:03:02,416 --> 00:03:04,383
it may seem impossible for life
55
00:03:04,385 --> 00:03:08,320
to survive in such
hostile environments,
56
00:03:08,322 --> 00:03:11,690
but here on earth,
life exists against the odds
57
00:03:11,692 --> 00:03:15,561
in some very strange places.
58
00:03:15,563 --> 00:03:18,363
Life has actually permeated
every part of our planet.
59
00:03:18,365 --> 00:03:19,398
There are places
where you're like,
60
00:03:19,400 --> 00:03:21,133
"how did you even get there?"
61
00:03:24,138 --> 00:03:26,471
narrator: At first glance,
a beautiful lake
62
00:03:26,473 --> 00:03:29,208
might seem like
a good place for life,
63
00:03:29,210 --> 00:03:34,112
but california's salton sea
is no paradise.
64
00:03:34,114 --> 00:03:37,249
The toxic salt waters
are killer...
65
00:03:40,421 --> 00:03:44,523
...Surrounded by scorched desert
66
00:03:44,525 --> 00:03:49,094
and volcanic geothermal fields.
67
00:03:49,096 --> 00:03:50,862
It's a deadly environment.
68
00:03:53,267 --> 00:03:56,868
One of the last places on earth
you'd expect to find life
69
00:03:56,870 --> 00:03:59,638
would be in boiling mud vents.
70
00:04:01,742 --> 00:04:05,377
You can start to hear
these vents because there's gas,
71
00:04:05,379 --> 00:04:09,548
and there's water and mud slurry
that's coming out, right here.
72
00:04:09,550 --> 00:04:13,252
So these are
active mud volcanoes.
73
00:04:13,254 --> 00:04:14,586
It's really hot.
74
00:04:14,588 --> 00:04:19,725
It's, like...
164 degrees fahrenheit.
75
00:04:19,727 --> 00:04:23,428
Narrator: But life is resilient,
finding a home even here,
76
00:04:23,430 --> 00:04:27,266
inside volcanic vents
in the california desert.
77
00:04:27,268 --> 00:04:29,301
We're in the middle
of a really hot desert,
78
00:04:29,303 --> 00:04:31,703
and as the mud comes up,
it's coming up hot,
79
00:04:31,705 --> 00:04:33,472
and it's kind of acid,
80
00:04:33,474 --> 00:04:36,174
and yet there can be microbes
in environments like this,
81
00:04:36,176 --> 00:04:38,543
happily thriving away.
82
00:04:38,545 --> 00:04:41,546
This is an environment that is
actually conducive to life,
83
00:04:41,548 --> 00:04:44,616
even though we think
it might not be.
84
00:04:44,618 --> 00:04:46,885
Narrator: Almost every inch
of the earth's surface
85
00:04:46,887 --> 00:04:51,323
is teeming
with microscopic life-forms.
86
00:04:51,325 --> 00:04:52,958
The thing about life on earth
87
00:04:52,960 --> 00:04:57,195
is that it exists in so many
different environments
88
00:04:57,197 --> 00:04:59,798
under such harsh,
extreme conditions.
89
00:04:59,800 --> 00:05:02,768
It's like it hangs on,
no matter what you throw at it.
90
00:05:02,770 --> 00:05:06,138
Very dry, high pressure,
very hot,
91
00:05:06,140 --> 00:05:08,607
even in high radiation
environments,
92
00:05:08,609 --> 00:05:10,976
which would kill
a human within seconds.
93
00:05:14,014 --> 00:05:15,914
Narrator: Life even survives
94
00:05:15,916 --> 00:05:18,984
being bombed with asteroids
and meteorites.
95
00:05:20,988 --> 00:05:22,821
We have a wonderful
indirect example
96
00:05:22,823 --> 00:05:25,557
of just how tenacious life is,
and that's the fact
97
00:05:25,559 --> 00:05:28,126
that it survived
the late heavy bombardment.
98
00:05:30,064 --> 00:05:31,563
Narrator:
The late heavy bombardment
99
00:05:31,565 --> 00:05:34,199
was a violent assault
on young earth,
100
00:05:34,201 --> 00:05:38,170
where life had just gotten
a foothold.
101
00:05:38,172 --> 00:05:41,440
Experts think
around 4 billion years ago,
102
00:05:41,442 --> 00:05:43,709
asteroids comets
and space debris
103
00:05:43,711 --> 00:05:46,912
rained down
on the inner solar system.
104
00:05:46,914 --> 00:05:49,181
This rocky barrage
would've melted parts
105
00:05:49,183 --> 00:05:52,818
of the earth's crust
and boiled away oceans.
106
00:05:52,820 --> 00:05:58,223
It was a violent time
called the hadean period.
107
00:05:58,225 --> 00:06:01,026
The hadean named, after hades,
named after the underworld,
108
00:06:01,028 --> 00:06:02,461
after hell.
109
00:06:02,463 --> 00:06:06,531
It was a brutally unpleasant
place to be.
110
00:06:06,533 --> 00:06:09,101
It was spewing its own innards
out into the surface
111
00:06:09,103 --> 00:06:12,571
in this intense cycle
of hot volcanism.
112
00:06:15,976 --> 00:06:17,342
Narrator: If life on earth
113
00:06:17,344 --> 00:06:19,244
overcame these
hellish conditions,
114
00:06:19,246 --> 00:06:24,383
then perhaps life
can survive anywhere.
115
00:06:24,385 --> 00:06:25,851
Straugh: I think
if it can happen on earth,
116
00:06:25,853 --> 00:06:28,086
I think it can happen
on other planets.
117
00:06:28,088 --> 00:06:29,921
I think life finds a way,
118
00:06:29,923 --> 00:06:32,624
and I think we need
to go looking for it.
119
00:06:34,728 --> 00:06:38,063
Narrator: The question is,
what exactly are we looking for?
120
00:06:39,933 --> 00:06:41,366
Plait: What is life?
121
00:06:41,368 --> 00:06:42,934
You know, that seems
like a simple question,
122
00:06:42,936 --> 00:06:45,337
but it's not
that easy to answer.
123
00:06:45,339 --> 00:06:47,339
Life is incredibly hard
to define, right?
124
00:06:47,341 --> 00:06:49,007
It's sort of like, you know it
when you see it,
125
00:06:49,009 --> 00:06:51,743
but how do you
write down the rules?
126
00:06:51,745 --> 00:06:53,545
Stricker: Every time we think
we have a grasp,
127
00:06:53,547 --> 00:06:55,680
there's this new form
that comes about
128
00:06:55,682 --> 00:06:59,584
and completely questions
that entire definition.
129
00:06:59,586 --> 00:07:01,920
There's a joke in astrobiology
that if you ask
130
00:07:01,922 --> 00:07:04,289
200 scientists
for a definition of life,
131
00:07:04,291 --> 00:07:07,426
you'll get
200 different answers.
132
00:07:07,428 --> 00:07:10,695
Narrator: Life can be
as intricate as us humans
133
00:07:10,697 --> 00:07:15,300
or as simple as single-celled
organisms, like bacteria,
134
00:07:15,302 --> 00:07:20,205
but there are some things
all life-forms do.
135
00:07:20,207 --> 00:07:22,441
Plait:In broad terms,
life consumes things.
136
00:07:22,443 --> 00:07:25,277
It breathes. It eats.
It excretes.
137
00:07:25,279 --> 00:07:28,613
It grows. It reproduces.
It's complex.
138
00:07:31,819 --> 00:07:36,888
Narrator: Life has transformed
the earth in all sorts of ways,
139
00:07:36,890 --> 00:07:39,691
but life is
still just an accident.
140
00:07:42,629 --> 00:07:45,897
Life, as I see it,
is just a chemical reaction,
141
00:07:45,899 --> 00:07:49,568
but it's the most important
and special chemical reaction
142
00:07:49,570 --> 00:07:52,170
in the universe.
143
00:07:52,172 --> 00:07:55,273
Narrator: If life is just
a product of chemistry,
144
00:07:55,275 --> 00:07:56,441
then what are the odds of it
145
00:07:56,443 --> 00:08:00,111
starting anywhere
in the universe?
146
00:08:00,113 --> 00:08:01,980
One thing we know
about chemistry
147
00:08:01,982 --> 00:08:04,483
is that
given the right conditions,
148
00:08:04,485 --> 00:08:09,621
the same chemical reaction
will reliably occur.
149
00:08:09,623 --> 00:08:11,356
Narrator:
It's like a game of chance.
150
00:08:11,358 --> 00:08:15,126
For life to win, the conditions
need to be just right,
151
00:08:15,128 --> 00:08:18,463
but to figure out the odds,
we need to understand
152
00:08:18,465 --> 00:08:22,200
what those conditions are
and how common they are.
153
00:08:22,202 --> 00:08:24,803
Oluseyi: So it comes down
to a numbers game.
154
00:08:24,805 --> 00:08:28,540
It's about statistics and
probabilities and likelihoods.
155
00:08:28,542 --> 00:08:31,042
Narrator:
It's like having to roll a 6
156
00:08:31,044 --> 00:08:34,312
for each condition for life.
157
00:08:34,314 --> 00:08:36,982
But how many 6s would you need?
158
00:08:36,984 --> 00:08:41,953
How many precise conditions
does life require to get going?
159
00:08:41,955 --> 00:08:46,124
You might have 100 dice,
roll them all, get all 6s.
160
00:08:46,126 --> 00:08:48,393
Only then do you get life.
161
00:08:48,395 --> 00:08:49,961
Narrator:
You could need hundreds
162
00:08:49,963 --> 00:08:52,597
or hundreds of thousands
of dice.
163
00:08:52,599 --> 00:08:54,399
We just don't know.
164
00:08:54,401 --> 00:08:57,636
We honestly have no clue
165
00:08:57,638 --> 00:09:01,273
how common or rare life is
in the universe.
166
00:09:01,275 --> 00:09:03,174
Plait: We don't know how life
originated here on earth,
167
00:09:03,176 --> 00:09:05,777
where we kind of understand
the conditions.
168
00:09:05,779 --> 00:09:08,780
There are a lot of different
ways life could've started.
169
00:09:10,884 --> 00:09:14,386
Is life rare? Is life common?
We don't where it lands.
170
00:09:15,522 --> 00:09:18,056
Narrator:
Putting odds on life existing
171
00:09:18,058 --> 00:09:22,994
is a waste of time
until we understand it better,
172
00:09:22,996 --> 00:09:27,098
and maybe our answers
don't lie here on earth.
173
00:09:27,100 --> 00:09:29,234
One way to crack this problem
174
00:09:29,236 --> 00:09:31,603
is to go looking for life
elsewhere.
175
00:09:31,605 --> 00:09:33,905
If we can find
other examples of life,
176
00:09:33,907 --> 00:09:37,509
we can immediately begin
to put a quantitative answer
177
00:09:37,511 --> 00:09:42,147
to how probable it is
for life to happen anywhere.
178
00:09:42,149 --> 00:09:44,316
Narrator: And the best place
to look for life
179
00:09:44,318 --> 00:09:47,886
might be in our own backyard...
180
00:09:49,389 --> 00:09:52,490
...Mars.
181
00:09:52,492 --> 00:09:54,292
If life can start here,
182
00:09:54,294 --> 00:09:57,862
then maybe life
could conquer the universe.
183
00:10:06,373 --> 00:10:10,809
[ explosions ]
184
00:10:10,811 --> 00:10:13,345
♪
185
00:10:13,347 --> 00:10:15,280
narrator: For life to conquer
the universe,
186
00:10:15,282 --> 00:10:19,117
first, it has to get going.
187
00:10:19,119 --> 00:10:20,585
When we look at life on earth,
188
00:10:20,587 --> 00:10:23,355
it's possible that it all
has a common ancestor.
189
00:10:23,357 --> 00:10:26,424
Life started at one spot,
branched out, and became
190
00:10:26,426 --> 00:10:30,395
all the different kinds
of life that we see.
191
00:10:30,397 --> 00:10:32,764
Narrator:
But how did it start?
192
00:10:32,766 --> 00:10:37,502
The first question to answer is,
what is life made of?
193
00:10:37,504 --> 00:10:40,438
Top of the list are the most
basic building blocks --
194
00:10:40,440 --> 00:10:43,708
chemical elements.
195
00:10:43,710 --> 00:10:45,610
Here's what I know about
the universe --
196
00:10:45,612 --> 00:10:49,748
the laws of physics
appear to be same everywhere.
197
00:10:49,750 --> 00:10:50,949
The chemical composition,
198
00:10:50,951 --> 00:10:55,320
the elements are the same
everywhere.
199
00:10:55,322 --> 00:10:57,322
And the cosmos creates
these elements,
200
00:10:57,324 --> 00:11:01,159
not from the big bang
but from stars.
201
00:11:01,161 --> 00:11:03,428
Narrator: Over the course
of a star's life,
202
00:11:03,430 --> 00:11:05,363
it creates elements.
203
00:11:05,365 --> 00:11:07,032
And when a star dies,
204
00:11:07,034 --> 00:11:11,803
these elements are blasted out
into space in a supernova,
205
00:11:11,805 --> 00:11:16,741
spreading the ingredients
for life out into the cosmos.
206
00:11:16,743 --> 00:11:19,844
We, the earth, our solar system,
207
00:11:19,846 --> 00:11:21,746
all the ingredients
that make us,
208
00:11:21,748 --> 00:11:26,284
us were forged in nuclear fires.
209
00:11:26,286 --> 00:11:30,955
So the death of stars
leads to the birth of life.
210
00:11:33,694 --> 00:11:36,194
Narrator: Those key ingredients
include oxygen,
211
00:11:36,196 --> 00:11:39,330
nitrogen, sulfur,
and phosphorus,
212
00:11:39,332 --> 00:11:44,202
but the element most central
to life as we know it is carbon.
213
00:11:45,739 --> 00:11:49,841
All life as we know it on earth
is based on carbon.
214
00:11:49,843 --> 00:11:52,377
Carbon forms the structure,
215
00:11:52,379 --> 00:11:55,747
the architecture
of our living molecules.
216
00:11:58,085 --> 00:12:00,819
Narrator: Carbon is
an incredibly versatile
217
00:12:00,821 --> 00:12:03,855
building material.
218
00:12:03,857 --> 00:12:07,826
It can bond with other elements
to form long-chain molecules,
219
00:12:07,828 --> 00:12:11,262
each with different properties.
220
00:12:11,264 --> 00:12:14,833
As an element, it seems to be
capable of producing
221
00:12:14,835 --> 00:12:19,337
a vast and complex chemistry,
222
00:12:19,339 --> 00:12:24,943
and that complex chemistry
is what we find in life.
223
00:12:24,945 --> 00:12:27,645
Narrator:
We call this organic chemistry.
224
00:12:27,647 --> 00:12:31,116
♪
225
00:12:31,118 --> 00:12:33,918
but getting from
basic organic molecules
226
00:12:33,920 --> 00:12:37,021
to complex life-forms
is a big leap.
227
00:12:37,023 --> 00:12:40,792
We don't really have
the slightest idea,
228
00:12:40,794 --> 00:12:45,597
to be honest, about how life
on earth got started.
229
00:12:45,599 --> 00:12:49,300
Scharf: A really big question
is, how do you go from a mix
230
00:12:49,302 --> 00:12:54,873
of relatively simple organic
molecules to a living system?
231
00:12:54,875 --> 00:12:57,742
Narrator: We know it all starts
with basic elements created
232
00:12:57,744 --> 00:12:59,377
in massive quantities...
233
00:12:59,379 --> 00:13:00,779
[ explosion ]
234
00:13:00,781 --> 00:13:03,515
...By the death of stars.
235
00:13:03,517 --> 00:13:07,018
But how do you start connecting
those lego bricks together
236
00:13:07,020 --> 00:13:08,987
to build that first cell?
237
00:13:08,989 --> 00:13:12,557
The short answer is,
"we don't know,"
238
00:13:12,559 --> 00:13:16,628
but we have some ideas
of potential steps.
239
00:13:16,630 --> 00:13:18,997
Narrator:
Chains of organic molecules
240
00:13:18,999 --> 00:13:20,732
become more and more complex.
241
00:13:20,734 --> 00:13:23,468
Amino acids form proteins.
242
00:13:23,470 --> 00:13:29,207
Fatty acids form phospholipids,
which makes cell membranes.
243
00:13:29,209 --> 00:13:31,876
Nucleic acids form dna,
244
00:13:31,878 --> 00:13:35,079
the molecule that stores
genetic information.
245
00:13:35,081 --> 00:13:39,684
Eventually,
a simple cell emerges.
246
00:13:39,686 --> 00:13:42,353
So all of the bits you need
to plug together
247
00:13:42,355 --> 00:13:44,489
to build a cell from scratch
248
00:13:44,491 --> 00:13:48,426
seems to exist in outer space.
249
00:13:48,428 --> 00:13:50,862
We found organic compounds
everywhere.
250
00:13:50,864 --> 00:13:53,031
They're all over the place --
251
00:13:53,033 --> 00:13:56,935
planets, comets, gas clouds.
252
00:13:58,505 --> 00:14:01,406
The very basic
ingredients of life
253
00:14:01,408 --> 00:14:05,410
available elsewhere
in our solar system,
254
00:14:05,412 --> 00:14:08,079
so there could be life
everywhere.
255
00:14:08,081 --> 00:14:11,282
♪
256
00:14:11,284 --> 00:14:12,951
narrator: In 2018,
257
00:14:12,953 --> 00:14:16,621
nasa announces it's found
organic molecules
258
00:14:16,623 --> 00:14:18,723
on another planet,
259
00:14:18,725 --> 00:14:23,962
a planet we've always suspected
of harboring alien life --
260
00:14:23,964 --> 00:14:26,364
...Mars.
261
00:14:26,366 --> 00:14:28,733
So whenever nasa has a
press conference, and they say,
262
00:14:28,735 --> 00:14:31,703
"hey, I have some results
to report on about mars,"
263
00:14:31,705 --> 00:14:33,404
everyone goes nuts.
264
00:14:33,406 --> 00:14:36,040
Dartnell:
The internet goes mad.
265
00:14:36,042 --> 00:14:38,576
Maybe we've got photograph
evidence of the green men
266
00:14:38,578 --> 00:14:40,712
in a ufo.
267
00:14:40,714 --> 00:14:42,313
Lanza:
This time, it's the martians.
268
00:14:42,315 --> 00:14:45,383
They're going to tell us
they found a martian.
269
00:14:45,385 --> 00:14:47,552
The world listens
'cause everyone wants to know.
270
00:14:47,554 --> 00:14:49,254
Everyone asks the question,
271
00:14:49,256 --> 00:14:50,989
"have we found evidence
of life?"
272
00:14:53,293 --> 00:14:54,726
narrator: For 6 years,
273
00:14:54,728 --> 00:14:57,562
the mars curiosity
rover has been exploring
274
00:14:57,564 --> 00:14:59,664
a region called gale crater,
275
00:14:59,666 --> 00:15:02,567
hunting for signs of
ancient life.
276
00:15:04,905 --> 00:15:08,239
A bit like
fossil-hunting on earth.
277
00:15:08,241 --> 00:15:10,541
Gale crater is not unlike
places on earth
278
00:15:10,543 --> 00:15:13,411
that can preserve fossils,
so a really good example of this
279
00:15:13,413 --> 00:15:17,215
would be the petrified forest
in arizona.
280
00:15:17,217 --> 00:15:21,653
This looks like a piece of wood,
but in fact, it is stone.
281
00:15:21,655 --> 00:15:24,956
It is all stone,
but it used to be a tree.
282
00:15:24,958 --> 00:15:29,460
This fossil lived
200 million years ago.
283
00:15:29,462 --> 00:15:31,329
Narrator:
This patch of desert in arizona
284
00:15:31,331 --> 00:15:33,197
once looked
completely different.
285
00:15:35,368 --> 00:15:37,702
Lanza: This landscape looks
very dry right now,
286
00:15:37,704 --> 00:15:39,070
but 200 million years ago,
287
00:15:39,072 --> 00:15:44,008
it was wet swampland
with trees and flowing water.
288
00:15:45,612 --> 00:15:47,211
Narrator:
Like the petrified forest,
289
00:15:47,213 --> 00:15:51,082
mars has also changed over time.
290
00:15:51,084 --> 00:15:55,853
Gale crater was once a lake bed
filled with fresh water.
291
00:15:55,855 --> 00:15:59,624
And it was just so exciting
because we knew then
292
00:15:59,626 --> 00:16:03,194
that we had landed
right on top of an environment
293
00:16:03,196 --> 00:16:05,496
that once had tons
of flowing water
294
00:16:05,498 --> 00:16:08,232
and could very well have
preserved organic materials,
295
00:16:08,234 --> 00:16:11,235
even though it looks very barren
and desolate to our eyes.
296
00:16:13,707 --> 00:16:15,206
Narrator: In 2018,
297
00:16:15,208 --> 00:16:18,409
curiosity drills into
this ancient martian lake
298
00:16:18,411 --> 00:16:21,245
and discovers organic molecules.
299
00:16:24,484 --> 00:16:27,652
Finding organics on mars
is so exciting
300
00:16:27,654 --> 00:16:29,454
just because, I mean, wow.
301
00:16:29,456 --> 00:16:31,622
That is -- those are
the building blocks of life,
302
00:16:31,624 --> 00:16:34,025
not just the elements,
but actual molecules.
303
00:16:34,027 --> 00:16:36,661
There was a wave of excitement
304
00:16:36,663 --> 00:16:38,830
after the announcement
of organics
305
00:16:38,832 --> 00:16:41,332
found on mars
and complex organics.
306
00:16:41,334 --> 00:16:43,968
It's not totally indicative
that life is there,
307
00:16:43,970 --> 00:16:46,504
but it's a really good
telltale sign
308
00:16:46,506 --> 00:16:51,542
that there may be
possibly life-forms on mars.
309
00:16:51,544 --> 00:16:54,612
Narrator: The results aren't
proof of martians,
310
00:16:54,614 --> 00:16:58,816
but the ancient lake bed
is evidence that the red planet
311
00:16:58,818 --> 00:17:02,854
once had something else
crucial for life --
312
00:17:02,856 --> 00:17:04,188
liquid water.
313
00:17:04,190 --> 00:17:07,558
♪
314
00:17:07,560 --> 00:17:09,627
it's one thing if you have
all these ingredients
315
00:17:09,629 --> 00:17:11,095
lying around for life.
316
00:17:11,097 --> 00:17:12,697
You could have, you know,
carbon over here and hydrogen
317
00:17:12,699 --> 00:17:15,033
over here,
maybe methane or whatever.
318
00:17:15,035 --> 00:17:16,534
You have to mix them together,
319
00:17:16,536 --> 00:17:21,139
so you need something for them
to be in, a medium of some sort.
320
00:17:21,141 --> 00:17:22,874
Narrator: Life needs a liquid
321
00:17:22,876 --> 00:17:26,844
to mix essential chemicals
together.
322
00:17:26,846 --> 00:17:28,212
We're used to thinking of earth
323
00:17:28,214 --> 00:17:33,217
as the only water world
in our solar system,
324
00:17:33,219 --> 00:17:35,920
but new evidence says
otherwise...
325
00:17:38,625 --> 00:17:42,126
...As extraterrestrial visitors
326
00:17:42,128 --> 00:17:46,531
carrying liquid water
from outer space reveal.
327
00:17:54,841 --> 00:17:59,277
[ explosions ]
328
00:17:59,279 --> 00:18:00,678
♪
329
00:18:00,680 --> 00:18:02,480
narrator: It's no coincidence
330
00:18:02,482 --> 00:18:05,416
our blue planet is
a water world.
331
00:18:05,418 --> 00:18:09,587
There are more than
366 million trillion gallons
332
00:18:09,589 --> 00:18:12,590
of water on earth.
333
00:18:12,592 --> 00:18:16,394
It even makes up
60% of our bodies.
334
00:18:16,396 --> 00:18:18,596
I think life on earth
could be easily described
335
00:18:18,598 --> 00:18:20,898
as water chemistry.
336
00:18:20,900 --> 00:18:24,569
That is the essential feature
of life on earth.
337
00:18:24,571 --> 00:18:27,038
Narrator:
Some is locked up in ice caps
338
00:18:27,040 --> 00:18:30,007
or as vapor in the air,
339
00:18:30,009 --> 00:18:34,979
but 96% of liquid water
is in our oceans.
340
00:18:34,981 --> 00:18:37,248
Well, earth is really special.
341
00:18:37,250 --> 00:18:39,951
There's no other place like it
that we've found.
342
00:18:39,953 --> 00:18:43,654
It's a pretty substantial planet
with liquid water
343
00:18:43,656 --> 00:18:45,756
covering 70% of the surface.
344
00:18:45,758 --> 00:18:48,426
All life on the earth requires
bodies of water
345
00:18:48,428 --> 00:18:49,660
in order to survive.
346
00:18:49,662 --> 00:18:51,295
No water, no life.
347
00:18:52,765 --> 00:18:56,834
Narrator: Water is what chemists
call a solvent,
348
00:18:56,836 --> 00:19:00,505
and it's the best solvent
we know of.
349
00:19:00,507 --> 00:19:04,108
It can dissolve more substances
than any other liquid,
350
00:19:04,110 --> 00:19:07,645
allowing molecules
to mix and interact.
351
00:19:07,647 --> 00:19:10,948
Wherever water goes,
it transports
352
00:19:10,950 --> 00:19:15,052
valuable chemicals, minerals,
and nutrients.
353
00:19:15,054 --> 00:19:16,521
Oluseyi:
If there was no liquid,
354
00:19:16,523 --> 00:19:18,489
things would just sit around
separately.
355
00:19:18,491 --> 00:19:20,825
You need this constant
interaction,
356
00:19:20,827 --> 00:19:23,294
and you need
a different chemical mix,
357
00:19:23,296 --> 00:19:25,530
and water does all of that.
358
00:19:27,534 --> 00:19:31,202
And so a lot of our searches
for lifelike planets,
359
00:19:31,204 --> 00:19:34,605
or earthlike planets,
outside our solar system
360
00:19:34,607 --> 00:19:38,109
are based on this sort of
primary assumption
361
00:19:38,111 --> 00:19:40,011
that we need liquid water.
362
00:19:42,248 --> 00:19:44,849
Narrator: We've long thought
earth has liquid water
363
00:19:44,851 --> 00:19:49,620
because of its unique position
in the solar system.
364
00:19:49,622 --> 00:19:52,990
It's right in this zone that
we call the habitable zone
365
00:19:52,992 --> 00:19:56,561
where the sunlight
can support liquid water
366
00:19:56,563 --> 00:19:58,262
on the surface of the planet.
367
00:19:58,264 --> 00:20:01,666
♪
368
00:20:01,668 --> 00:20:04,101
narrator: But we have now
discovered that liquid water
369
00:20:04,103 --> 00:20:07,438
might exist in places
we never expected.
370
00:20:10,043 --> 00:20:14,779
In 1998, a meteorite crash-lands
in texas.
371
00:20:16,149 --> 00:20:19,350
[ explosion ]
372
00:20:19,352 --> 00:20:22,286
today, scientists
at arizona state university
373
00:20:22,288 --> 00:20:26,023
are still studying its secrets.
374
00:20:26,025 --> 00:20:27,792
We had no idea
that it would contain
375
00:20:27,794 --> 00:20:31,095
this really,
really spectacular finding.
376
00:20:31,097 --> 00:20:35,066
Narrator: It contains
a mysterious purple mineral.
377
00:20:35,068 --> 00:20:39,103
The exotic color comes from
exposure to cosmic radiation,
378
00:20:39,105 --> 00:20:42,873
but the compound itself
is very ordinary.
379
00:20:42,875 --> 00:20:44,842
It's actually sodium chloride,
380
00:20:44,844 --> 00:20:48,312
which is essentially
the same mineral as table salt,
381
00:20:48,314 --> 00:20:51,349
but what's really cool
is that it actually contains
382
00:20:51,351 --> 00:20:54,118
little globules of liquid water,
383
00:20:54,120 --> 00:20:57,588
and that liquid water
was trapped in these crystals
384
00:20:57,590 --> 00:21:00,992
4 1/2 billion years ago.
385
00:21:00,994 --> 00:21:04,095
Narrator: In 2018, scientists
reexamined the crystals
386
00:21:04,097 --> 00:21:08,366
and discovered the liquid water
wasn't traveling alone.
387
00:21:08,368 --> 00:21:11,802
We've now actually found
organic compounds in association
388
00:21:11,804 --> 00:21:15,373
with this liquid water
in these salt crystals,
389
00:21:15,375 --> 00:21:17,842
and that's something
that's really new
390
00:21:17,844 --> 00:21:20,077
and really spectacular.
391
00:21:22,582 --> 00:21:24,348
Thaller:
We actually found amino acids,
392
00:21:24,350 --> 00:21:27,752
the building blocks of all
of our proteins, even our dna,
393
00:21:27,754 --> 00:21:29,387
and we found liquid water,
394
00:21:29,389 --> 00:21:32,523
the very building blocks
of life, inside a meteorite.
395
00:21:34,761 --> 00:21:36,861
Narrator: So could life exist
396
00:21:36,863 --> 00:21:38,963
somewhere else
in our solar system?
397
00:21:38,965 --> 00:21:42,767
♪
398
00:21:42,769 --> 00:21:47,071
a nasa mission to saturn
turned up some shocking results.
399
00:21:47,073 --> 00:21:52,176
The cassini space probe flew
beneath saturn's moon enceladus.
400
00:21:52,178 --> 00:21:54,779
Dartnell:
Enceladus, no one cared about.
401
00:21:54,781 --> 00:22:01,185
It was a tiny, little snowball
of a world.
402
00:22:01,187 --> 00:22:04,221
Narrator: But enceladus
surprised everyone.
403
00:22:06,793 --> 00:22:11,028
Geysers of liquid water,
dozens of them,
404
00:22:11,030 --> 00:22:14,165
blast out of trenches
along the moon's surface,
405
00:22:14,167 --> 00:22:17,535
coming from
a vast subsurface ocean.
406
00:22:21,507 --> 00:22:24,508
Oceans on earth
are full of life.
407
00:22:27,747 --> 00:22:30,781
Could the same be true
of enceladus?
408
00:22:30,783 --> 00:22:33,284
Mckay:
I'm a big fan of enceladus.
409
00:22:33,286 --> 00:22:37,054
I think it's by far and away
the best place to go
410
00:22:37,056 --> 00:22:39,190
to search for evidence of life.
411
00:22:39,192 --> 00:22:40,658
Narrator: In 2018,
412
00:22:40,660 --> 00:22:43,694
researchers analyzing
the cassini data
413
00:22:43,696 --> 00:22:46,330
discovered that the plumes
of enceladus
414
00:22:46,332 --> 00:22:49,367
contain
complex organic molecules.
415
00:22:49,369 --> 00:22:52,903
Just simple molecules,
we find those, like methane,
416
00:22:52,905 --> 00:22:55,306
but the cassini results
are showing that there are
417
00:22:55,308 --> 00:22:59,944
these more complex, larger
organic molecules as well.
418
00:22:59,946 --> 00:23:03,013
Narrator: This is the first ever
detection of complex organics
419
00:23:03,015 --> 00:23:05,950
on an extraterrestrial
water world.
420
00:23:05,952 --> 00:23:09,487
All of a sudden,
here's water jetting out,
421
00:23:09,489 --> 00:23:13,724
carrying organic material, all
the ingredients needed for life.
422
00:23:13,726 --> 00:23:17,728
It was, like, too good
to be true.
423
00:23:17,730 --> 00:23:20,164
Narrator: But enceladus isn't
the only small world
424
00:23:20,166 --> 00:23:22,133
with a subsurface ocean.
425
00:23:22,135 --> 00:23:26,804
Other moons and dwarf planets
have liquid water, too.
426
00:23:26,806 --> 00:23:29,106
We think the most important
thing for life to form
427
00:23:29,108 --> 00:23:30,708
is the presence of liquid water,
428
00:23:30,710 --> 00:23:33,177
and our solar system
seems to be full of it.
429
00:23:35,548 --> 00:23:38,315
Sutter:
The discovery of liquid water
430
00:23:38,317 --> 00:23:40,050
in the outer solar system
431
00:23:40,052 --> 00:23:46,624
changes the rules of how life
might originate in the universe.
432
00:23:46,626 --> 00:23:50,227
♪
433
00:23:50,229 --> 00:23:51,729
narrator: Across the universe,
434
00:23:51,731 --> 00:23:56,567
alien life could be hiding
underneath the surface.
435
00:23:56,569 --> 00:24:00,271
Internal water oceans are
far more common
436
00:24:00,273 --> 00:24:03,607
than surface water oceans,
437
00:24:03,609 --> 00:24:07,111
so if there is a lot of life
out there in the universe,
438
00:24:07,113 --> 00:24:11,382
chances are it's in an internal
ocean under miles of ice.
439
00:24:13,486 --> 00:24:15,186
Narrator:
Who knows what might be lurking
440
00:24:15,188 --> 00:24:18,456
inside icy exoworlds?
441
00:24:18,458 --> 00:24:22,059
There may be jellyfish
and octopuses all over the place
442
00:24:22,061 --> 00:24:25,262
in exomoons and exoplanets
under ice
443
00:24:25,264 --> 00:24:28,899
that have civilizations
that we just don't know about.
444
00:24:28,901 --> 00:24:31,001
Narrator:
Finding liquid water oceans
445
00:24:31,003 --> 00:24:33,704
could open up a world
of possibilities.
446
00:24:35,942 --> 00:24:37,775
If you're not excited about
447
00:24:37,777 --> 00:24:41,011
intelligent extraterrestrial
octopus civilians,
448
00:24:41,013 --> 00:24:42,746
I don't know what to say.
449
00:24:44,984 --> 00:24:47,852
Narrator: The chances of finding
life in our solar system
450
00:24:47,854 --> 00:24:49,920
just got a heck of a lot better.
451
00:24:53,259 --> 00:24:57,328
Building blocks
and liquid water are common,
452
00:24:57,330 --> 00:25:00,164
but you need more than
just these two conditions
453
00:25:00,166 --> 00:25:02,099
for life to take hold.
454
00:25:02,101 --> 00:25:04,768
Life needs a spark.
455
00:25:04,770 --> 00:25:06,804
Life appears to need
some form of energy
456
00:25:06,806 --> 00:25:08,873
to actually get
the molecules interacting.
457
00:25:08,875 --> 00:25:10,975
One thing that may have helped
kick-start life on earth
458
00:25:10,977 --> 00:25:13,544
is ultraviolet radiation
from the sun.
459
00:25:13,546 --> 00:25:17,081
Narrator: Ultraviolet light
is emitted by all stars.
460
00:25:17,083 --> 00:25:21,385
There are billions of stars
in our galaxy.
461
00:25:21,387 --> 00:25:24,922
Can life get started
around any star,
462
00:25:24,924 --> 00:25:29,126
or is our sun unique?
463
00:25:35,434 --> 00:25:39,870
[ explosion ]
464
00:25:39,872 --> 00:25:43,607
narrator: Earth is
a solar-powered planet.
465
00:25:43,609 --> 00:25:47,378
At the bottom of the food chain,
plants use photosynthesis
466
00:25:47,380 --> 00:25:50,881
to convert sunlight
into chemical energy --
467
00:25:50,883 --> 00:25:53,083
food for the rest of us.
468
00:25:53,085 --> 00:25:56,754
Dartnell: I like eating
both grass, essentially wheat,
469
00:25:56,756 --> 00:25:59,390
and I also fancy
the odd hamburger from a cow
470
00:25:59,392 --> 00:26:00,724
that has eaten that grass.
471
00:26:00,726 --> 00:26:05,930
This whole ecosystem
is powered by sunshine.
472
00:26:05,932 --> 00:26:08,599
Narrator: But recent studies
have shed new light
473
00:26:08,601 --> 00:26:12,269
on how life developed
under our sun,
474
00:26:12,271 --> 00:26:16,440
specifically the role of
ultraviolet light.
475
00:26:16,442 --> 00:26:20,778
U.V.A. Radiation is useful
for breaking molecules up
476
00:26:20,780 --> 00:26:22,513
and triggering reactions.
477
00:26:22,515 --> 00:26:24,949
Maybe that played a role
in the origin of life.
478
00:26:24,951 --> 00:26:27,851
It breaks down
simple organic molecules,
479
00:26:27,853 --> 00:26:29,353
and then they can
rebuild themselves
480
00:26:29,355 --> 00:26:31,221
into things
that are more complex.
481
00:26:31,223 --> 00:26:32,823
You do that over and over again,
eventually,
482
00:26:32,825 --> 00:26:34,592
you somehow get life.
483
00:26:34,594 --> 00:26:37,962
♪
484
00:26:37,964 --> 00:26:39,630
narrator: Scientists think
life on earth
485
00:26:39,632 --> 00:26:42,866
started around
4 billion years ago...
486
00:26:42,868 --> 00:26:46,637
♪
487
00:26:46,639 --> 00:26:48,806
...A time
when earth's atmosphere
488
00:26:48,808 --> 00:26:50,274
gave little protection.
489
00:26:53,779 --> 00:26:56,914
U.V. Radiation levels
were 100 times higher.
490
00:26:59,218 --> 00:27:00,918
Was u.V. Essential
491
00:27:00,920 --> 00:27:05,789
for the development
of life's code, dna?
492
00:27:05,791 --> 00:27:10,160
We know that life on earth
stores information in dna
493
00:27:10,162 --> 00:27:13,964
and then uses that information
to build proteins,
494
00:27:13,966 --> 00:27:16,634
so you have the blueprints
and the bricks.
495
00:27:16,636 --> 00:27:21,171
The blueprints are the dna,
and the bricks are the protein.
496
00:27:21,173 --> 00:27:24,108
Dartnell: But we think that
the first life on earth,
497
00:27:24,110 --> 00:27:29,179
we used a chemical
which is much simpler.
498
00:27:29,181 --> 00:27:32,750
Narrator:
This simpler chemical was rna,
499
00:27:32,752 --> 00:27:37,187
dna's single-stranded
forefather.
500
00:27:37,189 --> 00:27:40,758
Rna is almost like
a two-for-one offer.
501
00:27:40,760 --> 00:27:43,394
It does both of
the fundamental things
502
00:27:43,396 --> 00:27:48,198
you need for a cell
in the same compound.
503
00:27:48,200 --> 00:27:53,303
So it was simultaneously
the bricks and the blueprint.
504
00:27:53,305 --> 00:27:56,540
Narrator: Unlike other
molecules, rna is more resistant
505
00:27:56,542 --> 00:27:59,910
to the high u.V. Environment
of early earth,
506
00:27:59,912 --> 00:28:03,747
allowing it to flourish.
507
00:28:03,749 --> 00:28:07,785
Rna eventually evolved
into dna,
508
00:28:07,787 --> 00:28:09,720
and life started.
509
00:28:09,722 --> 00:28:11,422
Oluseyi:
To have life on the planet,
510
00:28:11,424 --> 00:28:12,756
one important consideration
511
00:28:12,758 --> 00:28:15,025
is a certain amount of light
that's going to be needed
512
00:28:15,027 --> 00:28:17,261
and a certain type of light
that's going to be needed.
513
00:28:17,263 --> 00:28:22,032
♪
514
00:28:22,034 --> 00:28:25,502
narrator: So if all stars emit
some u.V. Radiation,
515
00:28:25,504 --> 00:28:28,972
can life start around any star?
516
00:28:28,974 --> 00:28:30,407
When we think about
looking for places
517
00:28:30,409 --> 00:28:32,209
that are conducive for life,
518
00:28:32,211 --> 00:28:33,610
we want to find a planet
519
00:28:33,612 --> 00:28:35,879
that might have enough
u.V. Radiation,
520
00:28:35,881 --> 00:28:39,483
so the star is, you know,
bright enough or close enough
521
00:28:39,485 --> 00:28:42,152
that's providing enough energy
to the surface for life,
522
00:28:42,154 --> 00:28:47,057
but we also don't want to have
too much u.V. Radiation.
523
00:28:47,059 --> 00:28:50,594
Narrator: It seems you need just
the right amount of u.V.
524
00:28:50,596 --> 00:28:56,133
♪
525
00:28:56,135 --> 00:28:59,770
the most common stars in
the galaxy are red dwarf stars.
526
00:29:02,608 --> 00:29:06,577
If red dwarf stars can harbor
life on planets around them,
527
00:29:06,579 --> 00:29:09,913
there's an awful lot
of real estate like that
528
00:29:09,915 --> 00:29:12,983
in our galaxy.
529
00:29:12,985 --> 00:29:15,953
Narrator: Red dwarf stars
could be good for life's chance
530
00:29:15,955 --> 00:29:19,990
of conquering the universe
in a number of ways.
531
00:29:19,992 --> 00:29:22,059
One, they represent over
three-quarters
532
00:29:22,061 --> 00:29:24,128
of all stars in the universe.
533
00:29:24,130 --> 00:29:26,797
Two, they live for over
a thousand times longer
534
00:29:26,799 --> 00:29:28,265
than sunlike stars,
535
00:29:28,267 --> 00:29:31,001
and, three, they seem to have
rocky planets around them
536
00:29:31,003 --> 00:29:34,138
much more often
than sunlike stars do.
537
00:29:34,140 --> 00:29:36,140
Narrator:
Those are the pros,
538
00:29:36,142 --> 00:29:39,543
but red dwarf stars
also have cons.
539
00:29:39,545 --> 00:29:44,615
For instance, they might not be
bright enough for life to begin.
540
00:29:44,617 --> 00:29:47,451
Some of the red dwarf stars
that we know emit
541
00:29:47,453 --> 00:29:49,920
less ultraviolet light
than the sun.
542
00:29:49,922 --> 00:29:51,855
They don't give off
much u.V. Light at all.
543
00:29:51,857 --> 00:29:53,290
Maybe on a planet around them,
544
00:29:53,292 --> 00:29:56,527
there isn't enough energy
to get life started.
545
00:29:56,529 --> 00:30:00,330
Narrator: Red dwarf stars are
also much more temperamental.
546
00:30:00,332 --> 00:30:03,000
They can go from being
gentle and quiet
547
00:30:03,002 --> 00:30:05,169
to having violent outbursts...
548
00:30:07,106 --> 00:30:10,007
...Stellar flares.
549
00:30:10,009 --> 00:30:13,310
These types of stars
have incredibly strong flares.
550
00:30:13,312 --> 00:30:15,012
That means they're shooting off
551
00:30:15,014 --> 00:30:18,081
a bunch of energetic particles
and radiation
552
00:30:18,083 --> 00:30:22,853
and light that's baking
the surface of those planets.
553
00:30:22,855 --> 00:30:24,154
Radebaugh: If the star is just
554
00:30:24,156 --> 00:30:25,656
bombarding the surface
with u.V.,
555
00:30:25,658 --> 00:30:29,326
then it will destroy all of
those things necessary for life.
556
00:30:29,328 --> 00:30:32,496
It will actually destroy
the life itself.
557
00:30:32,498 --> 00:30:37,568
♪
558
00:30:37,570 --> 00:30:39,102
narrator:
These stellar flares
559
00:30:39,104 --> 00:30:41,004
could strip away
a planet's atmosphere,
560
00:30:41,006 --> 00:30:42,906
sterilizing the surface.
561
00:30:42,908 --> 00:30:46,777
♪
562
00:30:46,779 --> 00:30:49,446
more research is needed,
but for now,
563
00:30:49,448 --> 00:30:54,117
the odds of life thriving around
dwarf stars are a toss-up.
564
00:30:54,119 --> 00:30:58,555
♪
565
00:30:58,557 --> 00:31:00,390
so far,
the only thing we know
566
00:31:00,392 --> 00:31:02,426
is that there is one kind
of star
567
00:31:02,428 --> 00:31:05,796
that's definitely
right for life --
568
00:31:05,798 --> 00:31:07,397
our sun.
569
00:31:07,399 --> 00:31:10,500
We know of life in one place in
the universe, and that's here.
570
00:31:10,502 --> 00:31:12,870
That's earth.
571
00:31:12,872 --> 00:31:18,508
Narrator: Only 4% of stars in
the universe are like our sun.
572
00:31:18,510 --> 00:31:22,212
So if life can only get started
around these rare,
573
00:31:22,214 --> 00:31:24,047
medium-sized stars,
574
00:31:24,049 --> 00:31:26,316
the chances
are not looking good.
575
00:31:26,318 --> 00:31:31,455
♪
576
00:31:31,457 --> 00:31:34,725
but life may have an ace
up its sleeve.
577
00:31:34,727 --> 00:31:40,097
What if life can start on
just one planet and then spread?
578
00:31:40,099 --> 00:31:43,300
What if life travels
across the cosmos
579
00:31:43,302 --> 00:31:47,304
looking for planets to conquer?
580
00:31:53,646 --> 00:31:58,048
[ explosion ]
581
00:31:58,050 --> 00:32:00,217
♪
582
00:32:00,219 --> 00:32:03,086
narrator: Earth is
our only example of life
583
00:32:03,088 --> 00:32:06,423
emerging anywhere
in the universe.
584
00:32:06,425 --> 00:32:11,328
But what if life on earth
didn't start on earth at all?
585
00:32:11,330 --> 00:32:12,863
There's one idea that life
on earth
586
00:32:12,865 --> 00:32:16,099
actually didn't get going here
but was delivered from space.
587
00:32:16,101 --> 00:32:19,102
Narrator: Scientists
call this theory panspermia.
588
00:32:21,307 --> 00:32:23,540
Scharf: The idea of panspermia
essentially talks
589
00:32:23,542 --> 00:32:28,478
about the transferral of life
throughout the cosmos.
590
00:32:28,480 --> 00:32:31,481
Narrator: We know asteroids
and comets
591
00:32:31,483 --> 00:32:33,583
carry organic molecules.
592
00:32:33,585 --> 00:32:36,320
But could they carry
life itself?
593
00:32:36,322 --> 00:32:38,455
What if life starts
on one planet?
594
00:32:38,457 --> 00:32:42,993
Can it actually get itself
to a nearby planet?
595
00:32:42,995 --> 00:32:44,394
Is it possible that meteorites
596
00:32:44,396 --> 00:32:48,465
could actually transport
living beings?
597
00:32:48,467 --> 00:32:51,835
Narrator: For life to travel
around the cosmos,
598
00:32:51,837 --> 00:32:55,172
first, it needs to take flight.
599
00:32:55,174 --> 00:33:00,077
An asteroids is on a collision
course with an inhabited planet.
600
00:33:00,079 --> 00:33:02,779
So what happens if there's
a huge cataclysmic
601
00:33:02,781 --> 00:33:04,081
collision on a planet?
602
00:33:04,083 --> 00:33:06,717
Material is blasted off
into space.
603
00:33:06,719 --> 00:33:10,787
♪
604
00:33:10,789 --> 00:33:12,723
narrator:
The impact might kill life
605
00:33:12,725 --> 00:33:14,257
on the surface of that planet,
606
00:33:14,259 --> 00:33:19,296
but it's possible
some bacteria might escape,
607
00:33:19,298 --> 00:33:24,234
hitching a ride on chunks
of the planet's surface.
608
00:33:24,236 --> 00:33:26,436
A meteorite being ejected
from a planet
609
00:33:26,438 --> 00:33:27,871
after an asteroids impact --
610
00:33:27,873 --> 00:33:29,806
I mean, that's not going
to be an easy ride.
611
00:33:29,808 --> 00:33:32,743
But it turns out
it's not as bad as you think.
612
00:33:32,745 --> 00:33:35,679
Some bacteria are
very, very hard to kill.
613
00:33:35,681 --> 00:33:37,848
Some we don't even know
how to kill.
614
00:33:37,850 --> 00:33:41,084
Even the impact that actually
threw that rock into space --
615
00:33:41,086 --> 00:33:42,886
the bacteria, no problem.
616
00:33:42,888 --> 00:33:46,857
If those chunks of rock expelled
during asteroids collisions
617
00:33:46,859 --> 00:33:50,360
could actually hold onto
viable organisms,
618
00:33:50,362 --> 00:33:52,496
then it really could change
the way
619
00:33:52,498 --> 00:33:58,235
in which we think about life
spreading in the universe.
620
00:33:58,237 --> 00:34:01,071
Narrator: If the microbes
can survive takeoff,
621
00:34:01,073 --> 00:34:03,840
then they can start
their journey to a new home.
622
00:34:03,842 --> 00:34:06,676
The odds of life
conquering the universe
623
00:34:06,678 --> 00:34:08,145
seem to be getting better.
624
00:34:08,147 --> 00:34:11,481
The important question now is,
how long could that life,
625
00:34:11,483 --> 00:34:13,350
those bacteria,
those microorganisms
626
00:34:13,352 --> 00:34:16,686
inside that rock,
survive the space environment?
627
00:34:18,323 --> 00:34:21,291
Narrator: Exposure to
u.V. Radiation could be fatal,
628
00:34:21,293 --> 00:34:25,095
killing any life on the surface
of an asteroid.
629
00:34:25,097 --> 00:34:27,831
But experts think
that microbial passengers
630
00:34:27,833 --> 00:34:32,169
could still survive
by hiding underground.
631
00:34:32,171 --> 00:34:36,373
It doesn't take much to shield
a microorganism from u.V.
632
00:34:36,375 --> 00:34:39,576
Just a little bit of rock,
and you have enough protection
633
00:34:39,578 --> 00:34:43,380
to just hold on throughout
a journey to the next body,
634
00:34:43,382 --> 00:34:45,849
to your next home.
635
00:34:45,851 --> 00:34:49,619
Narrator: Eventually, they could
arrive at an uninhabited world
636
00:34:49,621 --> 00:34:52,155
that's ready and waiting
for life,
637
00:34:52,157 --> 00:34:54,658
but they're in for
a bumpy landing.
638
00:34:54,660 --> 00:34:58,595
Would the rock burn up coming
through a planet's atmosphere?
639
00:34:58,597 --> 00:35:02,099
It's in for a hot ride
but only for a few seconds,
640
00:35:02,101 --> 00:35:05,335
and only the outer layers
of that rock will blow off,
641
00:35:05,337 --> 00:35:08,138
and then it just falls and hits
the ground not that fast,
642
00:35:08,140 --> 00:35:11,174
a couple hundred miles an hour.
643
00:35:11,176 --> 00:35:13,076
If a human were in there,
that would be bad.
644
00:35:13,078 --> 00:35:15,879
But for bacteria, no big deal.
645
00:35:15,881 --> 00:35:18,548
Narrator:
The panspermia theory says
646
00:35:18,550 --> 00:35:21,151
life could start on
just one planet,
647
00:35:21,153 --> 00:35:26,089
then spread to another planet,
and possibly another.
648
00:35:26,091 --> 00:35:30,560
If we found alien life-forms,
would they look familiar?
649
00:35:30,562 --> 00:35:32,796
One of the biggest questions
about finding other life
650
00:35:32,798 --> 00:35:36,933
in the solar system is,
how similar will it be to us?
651
00:35:36,935 --> 00:35:39,836
If it's just like us,
it begs the question,
652
00:35:39,838 --> 00:35:41,771
did we have a common genesis?
653
00:35:41,773 --> 00:35:45,675
Did we originally
come from another planet?
654
00:35:45,677 --> 00:35:48,278
Narrator: One radical idea
655
00:35:48,280 --> 00:35:52,149
is that life on earth
came from mars.
656
00:35:52,151 --> 00:35:55,685
Imagine mars
3 1/4, 4 billion years ago.
657
00:35:55,687 --> 00:35:58,955
It was more earthlike then
than earth was at that point.
658
00:35:58,957 --> 00:36:00,790
The earth was still quite warm.
659
00:36:00,792 --> 00:36:02,826
Mars actually had cooled
off faster,
660
00:36:02,828 --> 00:36:04,561
had a thick atmosphere, water.
661
00:36:04,563 --> 00:36:06,997
Life could've arisen there.
662
00:36:06,999 --> 00:36:10,867
Narrator: Mars has been
hit repeatedly by meteors,
663
00:36:10,869 --> 00:36:15,038
sending chunks of the planet
flying off into space,
664
00:36:15,040 --> 00:36:19,876
and some of those chunks
have landed here, on earth.
665
00:36:19,878 --> 00:36:23,246
So this is
a really unusual meteorite.
666
00:36:23,248 --> 00:36:26,716
It was found near
the city of los angeles,
667
00:36:26,718 --> 00:36:29,252
and we actually know
668
00:36:29,254 --> 00:36:32,389
that it actually came from
the planet mars,
669
00:36:32,391 --> 00:36:35,425
and we know that because it has
gases trapped inside it
670
00:36:35,427 --> 00:36:38,028
that have the exact same
composition
671
00:36:38,030 --> 00:36:39,396
as the martian atmosphere.
672
00:36:39,398 --> 00:36:40,764
There's been a lot of transit
673
00:36:40,766 --> 00:36:43,466
between meteor strikes
hitting mars and then earth.
674
00:36:43,468 --> 00:36:45,035
There's a little bit of mars
on earth.
675
00:36:45,037 --> 00:36:47,370
There's a little bit
of earth on mars.
676
00:36:47,372 --> 00:36:51,308
It's possible that life
started on mars
677
00:36:51,310 --> 00:36:56,913
and was transferred to earth
inside of a meteorite.
678
00:36:56,915 --> 00:36:59,749
When you think about it,
maybe we're the immigrants.
679
00:36:59,751 --> 00:37:01,284
We are the martians.
680
00:37:01,286 --> 00:37:05,422
Life on earth started on mars
and got transferred here.
681
00:37:05,424 --> 00:37:09,359
♪
682
00:37:09,361 --> 00:37:11,461
narrator:
Panspermia could allow life
683
00:37:11,463 --> 00:37:13,463
to spread from planet to planet,
684
00:37:13,465 --> 00:37:15,532
conquering our solar system,
685
00:37:15,534 --> 00:37:19,869
but what about
even greater distances?
686
00:37:19,871 --> 00:37:24,274
In 2017, the cigar-shaped
space rock 'oumuamua
687
00:37:24,276 --> 00:37:26,243
appeared in our solar system.
688
00:37:26,245 --> 00:37:28,478
It came from interstellar space,
689
00:37:28,480 --> 00:37:32,549
and experts think it could be
carrying organic matter.
690
00:37:32,551 --> 00:37:34,651
One of the fascinating
things about 'oumuamua
691
00:37:34,653 --> 00:37:36,853
is it has sort of
a reddened surface.
692
00:37:36,855 --> 00:37:38,121
Now that could actually
partially be
693
00:37:38,123 --> 00:37:40,457
from the presence
of organic molecules.
694
00:37:40,459 --> 00:37:42,626
Narrator: Could life survive
695
00:37:42,628 --> 00:37:45,962
interstellar
or even intergalactic travel?
696
00:37:45,964 --> 00:37:49,766
Whether or not this is an easy
way to transfer life around
697
00:37:49,768 --> 00:37:52,636
in the universe,
it's still an open question.
698
00:37:52,638 --> 00:37:55,405
The possibility of transferring
life from star system
699
00:37:55,407 --> 00:37:59,009
to star system
seems a little bit remote.
700
00:37:59,011 --> 00:38:00,677
Narrator:
The immense distances
701
00:38:00,679 --> 00:38:02,479
and dangers
of interstellar travel
702
00:38:02,481 --> 00:38:04,447
would be hard to survive.
703
00:38:04,449 --> 00:38:08,251
Some experts think there is
one way for life
704
00:38:08,253 --> 00:38:11,821
to conquer the universe,
705
00:38:11,823 --> 00:38:14,991
but it won't be life
as we know it.
706
00:38:22,467 --> 00:38:26,870
[ explosion ]
707
00:38:26,872 --> 00:38:31,041
narrator: The universe is
unimaginably large.
708
00:38:31,043 --> 00:38:35,111
Many experts believe
there is life out there.
709
00:38:35,113 --> 00:38:37,347
We just have to go find it.
710
00:38:37,349 --> 00:38:40,617
Oluseyi: One of the things
I love about being a human
711
00:38:40,619 --> 00:38:44,621
is the fact that
I'm born with this curiosity.
712
00:38:44,623 --> 00:38:46,489
This curiosity drives us to
explore -- explore earth,
713
00:38:46,491 --> 00:38:50,060
explore our solar system
and beyond into the galaxy,
714
00:38:50,062 --> 00:38:52,896
look for other life-forms.
715
00:38:52,898 --> 00:38:55,098
Narrator:
But with current technology,
716
00:38:55,100 --> 00:38:59,369
it would take thousands of years
just to reach the nearest star.
717
00:38:59,371 --> 00:39:03,106
It's unlikely humans
will ever leave our galaxy.
718
00:39:05,644 --> 00:39:10,113
If life one day does spread
from earth into the cosmos,
719
00:39:10,115 --> 00:39:12,549
it's probably not just going to
be a bunch of meat bags,
720
00:39:12,551 --> 00:39:16,953
like us, but other forms of life
that are more suited
721
00:39:16,955 --> 00:39:21,191
for interstellar
and intergalactic travel.
722
00:39:21,193 --> 00:39:24,027
Narrator: Our fragile bodies are
not suited to the distances
723
00:39:24,029 --> 00:39:28,565
and dangers
of interstellar travel.
724
00:39:28,567 --> 00:39:33,169
Machine life may be more robust
for traveling between planets
725
00:39:33,171 --> 00:39:36,406
and between stars
than biological life.
726
00:39:38,677 --> 00:39:40,243
There are a lot of scientists
that think
727
00:39:40,245 --> 00:39:43,613
when we encounter aliens,
we won't be encountering them.
728
00:39:43,615 --> 00:39:45,215
We'll be encountering
their machines
729
00:39:45,217 --> 00:39:48,151
because we can build machines
that can last a million years,
730
00:39:48,153 --> 00:39:49,586
go from one star to the next.
731
00:39:49,588 --> 00:39:51,554
It's much easier
than transporting us,
732
00:39:51,556 --> 00:39:55,392
fragile gloppy bags of meat.
And so if we go out into space,
733
00:39:55,394 --> 00:40:00,897
we're more likely to find robots
than we are biological life.
734
00:40:00,899 --> 00:40:03,767
Narrator: For humanity to
discover alien life,
735
00:40:03,769 --> 00:40:08,238
humanity itself may have
to evolve
736
00:40:08,240 --> 00:40:13,510
from biological life
to artificial life.
737
00:40:13,512 --> 00:40:16,012
Oluseyi: What's really ironic
here is that
738
00:40:16,014 --> 00:40:19,949
while we're figuring out
the origin of life on earth,
739
00:40:19,951 --> 00:40:23,586
we humans could be inventing
a form of life on our own,
740
00:40:23,588 --> 00:40:27,090
and that is what we call
artificial intelligence.
741
00:40:27,092 --> 00:40:31,661
The development of a.I.,
self-replicating machines even,
742
00:40:31,663 --> 00:40:34,631
may very well be
just the next key transition
743
00:40:34,633 --> 00:40:37,033
in our evolutionary history.
744
00:40:39,871 --> 00:40:43,540
Narrator:
Could a superintelligent
self-replicating machine
745
00:40:43,542 --> 00:40:46,943
conquer the universe?
746
00:40:46,945 --> 00:40:51,815
Maybe this a.I. Can fashion
its own machines,
747
00:40:51,817 --> 00:40:55,285
create factories to create
resources to replicate itself,
748
00:40:55,287 --> 00:40:58,721
create ships
that will allow it travel
749
00:40:58,723 --> 00:41:01,024
from one place
in the universe to another.
750
00:41:03,862 --> 00:41:07,797
Narrator: But would a.I.
Represent a new form of life?
751
00:41:07,799 --> 00:41:09,132
Thaller:
I think the answer is yes.
752
00:41:09,134 --> 00:41:11,067
I think it actually goes on
from there.
753
00:41:11,069 --> 00:41:12,969
I think artificial intelligence
might be
754
00:41:12,971 --> 00:41:15,672
the next necessary stage
in evolution.
755
00:41:15,674 --> 00:41:19,209
We made the computers.
They are our children.
756
00:41:19,211 --> 00:41:24,380
I think of life as a process
that can retain its complexity
757
00:41:24,382 --> 00:41:29,352
and reproduce,
so bacteria are life.
758
00:41:29,354 --> 00:41:33,356
Humans are life,
and some future creation
759
00:41:33,358 --> 00:41:34,924
of advanced
artificial intelligence
760
00:41:34,926 --> 00:41:38,661
that can do those things
should also count as life.
761
00:41:41,600 --> 00:41:44,267
Narrator:
Life could take many forms,
762
00:41:44,269 --> 00:41:47,604
and in such a vast universe,
763
00:41:47,606 --> 00:41:52,609
it could be that life
is inevitable.
764
00:41:52,611 --> 00:41:55,044
With all those stars
and all those planets,
765
00:41:55,046 --> 00:41:58,147
I think, without a doubt,
there is a good chance
766
00:41:58,149 --> 00:42:02,285
that life has developed
elsewhere in our universe.
767
00:42:02,287 --> 00:42:05,421
Must life happen
in our universe?
768
00:42:05,423 --> 00:42:10,660
Is it an inevitable consequence
of processes in operation?
769
00:42:10,662 --> 00:42:13,296
Maybe, maybe not.
770
00:42:16,668 --> 00:42:21,538
Narrator: Until we find it,
we won't know for sure
771
00:42:21,540 --> 00:42:25,408
whether life can conquer
the universe.
772
00:42:25,410 --> 00:42:28,478
♪