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00:00our planet was born in fire then grew with disaster yet even then the elements of life
00:19were present water was soon present on the surface when calm it would provide a sheltered
00:29cradle for the first life on earth while the planet was born in fire it was baptized by ice for millions
00:46of years it was covered by a frozen shroud yet it seems that life not only persevered but prospered
00:54microbes evolved into a myriad creatures and one was the first to leave the oceans forever and tread
01:06on land only a few million years ago creatures that we most resemble began to walk the earth
01:13our own lives seem so fragile yet science tells us otherwise it tells us that we are but a part of the
01:22greatest journey ever made it tells us that all life is linked through time to those simple cells
01:29which drifted once in the first oceans of a miracle planet
01:52four and a half billion years ago the earth was a very different world under layers of thick gaseous
02:00clouds was a planet still hot from its birth with an atmosphere both dense and crushing
02:05bathed in filtered red light were oceans far deeper than those of today
02:19and there was one other great difference the early planet was probably only a tenth of the size that it is
02:31today but it was to grow and that chance and violent growth would prove crucial to life's history and to
02:40what we are today the early solar system was far more crowded than now where today the four inner planets orbit
02:50four and a half billion years ago were scores of smaller planets orbiting the Sun orbits of some were drawn by
02:59gravitational force towards each other and counters of awesome magnitude were unavoidable
03:04the force and heat of those collisions melted the rock but gravity would hold the two together and then weld them
03:18into one with each collision the planet would grow larger
03:23we believe that of the four innermost planets mercury was formed by only one or two such collisions
03:34while Venus almost the size of earth was formed by eight
03:39Mars may have escaped any collisions
03:44but earth grew largest perhaps from as many as 10 impacts
03:53and the last impact four and a half billion years ago would have a profound effect upon our world
04:05the giant body crashed into the center of the planet and gave earth its iron core
04:24the lighter debris was cast off into space and then drawn into orbit around the enlarged planet
04:43for some millions of years the earth had rings like the planet Saturn
04:47smaller collisions continued and from that debris was born our moon
04:59it was chance and chance alone which made our planet larger than any of the other planets close to the Sun
05:06and somehow somewhere in this chaos life began but quite where is open to conjecture and debate
05:20first light probably emerged on the earth by 4.4 billion years ago up fairly soon after the earth form
05:27my guess would be that this light came from Mars
05:32Mars was open for habitation before the earth is
05:36it's a much safer place to live if you're a microbe early in the solar system
05:41if life evolved on Mars rocks would get knocked off and this would seed the earth
05:46could life have formed on Mars
05:53we know because of the evidence of erosion that water once flowed freely on the surface
05:59that Mars did indeed have an atmosphere
06:02that conditions were suitable to sustain early primitive life
06:06but Mars is a small planet with weak gravity
06:09over time the atmosphere escaped into space
06:13most of the water vanished to either into space or held deep in the ground as permafrost
06:28we know too that earth has been hit by rocks that originated from Mars
06:32some scientists are positive that primitive microbial life could withstand that journey
06:37but the earth because of its size had enough gravity to keep its oceans
06:44over the ages continents have shifted their positions wind and rain shaping and reshaping the surface
06:53ice has scraped its way across the face of the land and the seas have risen and fallen again and again over time
07:04here in Greenland are some of the oldest exposed rocks ever to have been found
07:11and one belt of rock four kilometers almost two miles long
07:19may take us back as far as we can go in the long history of this planet's existence
07:25Dr. Minnick Rosing of the Geological Museum of Copenhagen has visited Greenland many times in his research for evidence of Earth's early history
07:44and close to the margin of the glaciers at a place called Isua
07:49he has found one of the oldest rock beds on the face of the planet
07:53here is the geological evidence that this was once an ancient seabed
07:59this rock was once molten lava which flowed 3.8 billion years ago
08:05its shape and structure identify it as pillow lava which can only form underwater
08:13pillow lavas show you that there was oceans on there or that there was water on the surface of Earth 3.8 billion years ago
08:22and we know on the ocean floor today that this is the habitat of many life forms
08:27and this could be a place where life emerged on Earth in such environments
08:33and this is a very rare thing we have been walking now for a couple of hours through rocks where you can't see anything
08:38and then suddenly there's like one square meter where you can look 3.8 billion years back in time and see what happened on Earth at that time
08:47so there are a few very rare glimpses where you can look way way back to the most distant parts of Earth's history
08:55but there is another rock unremarkable to look at which hints that life might also have been present
09:02only a meter or so square no larger than a beach towel
09:06it too is 3.8 billion years old
09:10this rock was also part of an ancient seabed
09:13but it is the black band which fascinates minic rosing
09:17this is a layer of fossilized carbon which he believes might be the earliest evidence of life
09:24under the microscope tiny black grains can be seen
09:28these possibly are grains of carbon the building blocks of life
09:32if so there may have been tiny microorganisms drifting in the water that were alive
09:38taking in nutrients reproducing and then dying and dropping slowly to the ocean floor
09:44when the carbon was deposited those billions of years ago
09:48the thin straight lines on the rock show it was undisturbed
09:52proof that this was the bottom of a deep ocean
09:55and the thickness indicates that already life was plentiful
09:59this is not the emergence of life
10:02it cannot be because we have all this black color
10:05and that means that there was very efficient life that could make a lot of carbon
10:09and this life must have been very sophisticated
10:12so life must have been had a long prehistory
10:15and one could speculate that probably life formed on earth
10:18maybe 4.3 billion years ago
10:20when the oceans formed and the conditions for life were present
10:23life could have emerged at that time
10:25and definitely by 3.8 billion years ago
10:28life had reached the level of sophistication
10:30that allowed it to live in the water and produce a lot of carbon
10:33so it was highly advanced life at this time
10:40for these microorganisms the prerogative was simply to survive
10:52but the challenges to life were daunting
10:54the early solar system was still a violent place
11:02asteroids come hurtling out of space attracted by the greater size of the planet
11:07and on the face of the earth today
11:09we can see the scars of recent collisions
11:23this crater in Arizona is well known
11:26it's the Ballinger meteorite crater
11:28and was gouged from the surface only 50,000 years ago
11:35the impact crater is huge
11:401.2 kilometers across just under a mile
11:43and it was thought that the size of the meteor must have been the same
11:46so perhaps buried in the ground was a fortune in iron and nickel
11:51in the early 1900s the Standard Iron Company was formed by Daniel Barringer to dig out the perceived wealth
11:58when my grandfather came up this ridge and looked at it
12:00he imagined that the object that made this hole was at least as big as the bottom diameter of the crater
12:07which is again more than half a kilometer
12:10he thought this would be millions and millions of tons of nickel iron
12:15and it would be commercially immensely valuable that he could make millions of dollars here
12:19the mining venture lasted 27 years and in today's money cost around 10 million dollars
12:29but nothing of any value was found
12:36but while the mining venture gained nothing except a useless shaft
12:42there was to be a winner after all
12:46it was science
12:48in 1928 a paper was published which concluded that the mass of the meteor was far smaller than the size of the crater
12:55further mining was called off
13:01and shortly after Daniel Barringer died of a heart attack
13:06I think I could have easily made the same mistake because it's such a large hole
13:14and it's intuitively it seems like it would have had to be a huge rock that would have made it
13:21in fact the meteorite which caused this crater was no larger than the perimeter fence around the mine shaft
13:28science learned it was the force that was as critical as the size of the object
13:34but about four billion years ago the earth was hit by a massive space intruder
13:4310,000 times larger and a trillion times heavier than the rock which grazed the earth in Arizona
13:50at Stamford University in the United States
13:58Dr. Kevin Zanley of NASA and Dr. Norman Sleep from the university
14:03are studying the impacts of meteorites on earth
14:06but first they must look at the moon
14:09you'd like to look at it pretty early so you get nice shadows
14:12it's also pretty nice
14:13on the earth the evidence of the very earliest asteroid strikes have been weathered away by erosion
14:18or lost with the tectonic movements of the earth's crust
14:22let's see if we can orient it the same way
14:25whoa where is everything
14:27but the moon has been stable since its creation over four billion years ago
14:33so craters are there from that long distant past
14:38by looking at these craters they hope to estimate the number of times the early earth might have been hit
14:44it is far larger its gravitational attraction far stronger
14:48and they estimate that our planet was hit 25 times more often
15:01nobody is steering the asteroids that are going to hit
15:06and the earth being bigger just happens to get hit more often
15:11so what we do is we count the big craters on the moon
15:16and then we scale up to the much larger size of the earth
15:23and we find that the earth was hit by asteroids as large as 500 kilometers across
15:30at the same time that the moon was being hit by asteroids that are 100 or 200 kilometers across
15:36this is an impression of the relative sizes the largest is 500 kilometers
15:41that's over 300 miles across
15:44earth may have been hit as many as six times by an asteroid this size
15:51you have a 500 kilometer object moving at 20 kilometers a second stopping in 20 seconds
15:57delivering all of its energy in doing so and you produce an enormous explosion
16:03the amount of energy that you that is released in this event
16:09is more than enough to evaporate the world's oceans
16:19a massive asteroid from outer space heads straight for earth
16:22it's as large as the one that impacted over four billion years ago
16:27this computer simulation has been made with the scientific advice of geophysical experts
16:32to show the effects if the impact were to happen today
16:35the asteroid's diameter is larger than the main island of Japan
16:42even though it is moving at over 720,000 kilometers an hour
16:47that's almost 450,000 miles an hour
16:50the asteroid appears eerily slow because of its size
16:54the actual impact happens in the Pacific Ocean just under a thousand miles south of Japan
17:01or south of Japan
17:31The crust of the earth is peeled away like an orange skin by what is called the Crest Tsunami.
17:38Even the deepest part of the Pacific Ocean looks like a thin film.
17:43Huge chunks of debris the size of city blocks are hurled into the air.
18:02The entire Japanese archipelago is disintegrated as is some of the Asian continent.
18:13The shattered remains are hurled out into space way beyond the atmosphere to bombard the earth with deadly intent when they re-enter.
18:22At 7,000 meters, 23,000 feet, the rim of the crater is higher than many mountains on earth today.
18:44The size of the crater would be a distance of two and a half thousand miles or four thousand kilometers.
18:51And this is just the start.
19:01NASA has the world's largest collision test machine used to try and find out what would happen after the moment of impact.
19:08Okay.
19:13Dr. Peter Schultz fills a small tank with water to see how the ocean would react.
19:26The actual impact object is tiny, but it will hit the water at a speed 20 times faster than a bullet fired from a pistol.
19:38Dr. Peter Schultz fills a small tank with water to see how the ocean would react.
19:45Oh, gorgeous!
19:47Joe, that is gorgeous!
19:52Just one tiny aluminum bullet had this result.
19:56But the impact which created mayhem is not the entire story.
20:10To get the full picture, the moment of impact has been slowed down so that one second seems to last an eternity.
20:16At the moment of impact, it is like slamming the brakes on.
20:25The kinetic energy of the bullet is transformed into heat.
20:30White smoke rises.
20:32It may look like a splash, but it is actually water vapor.
20:35The heat vaporizes the water in an instant.
20:44And heat has a deadly potential.
20:50When an asteroid hits the surface of the Earth, the material is heated up to temperatures that get up to the point of say 4,000 to 6,000 degrees centigrade.
21:02This is as hot as the surface of the sun.
21:10An experiment was carried out at Hokkaido University in northern Japan to try and discover what could happen to the rock bed at the point of impact.
21:17A tiny rock was put into a special oven that could cook the sample to a temperature of over 2,000 Celsius, 3600 Fahrenheit.
21:35As the temperature rose higher, the rock began to melt and boil like water.
21:53The gas produced is called rock vapor.
21:56The rock vapor, when we generate this rock vapor, it will expand extremely fast.
22:06It expands so quickly that it can cover eventually the entire planet.
22:10When an impact hits, it's not just the crater that forms, it's not just the area where the impact occurred.
22:15It's all the heating that's created in the atmosphere and around it.
22:19So heat really is the killer.
22:21Moments after the impact, rock vapor, the temperature of the sun begins to engulf the world.
22:39Could any life at all survive this impact?
22:43Immediately after the impact, the rock vapor rises up from the crater in a dome, then spreads out in all directions across the globe.
23:03Three hours after the impact south of Japan, the expanding wall of vaporized rock reaches the mountain.
23:12The Himalayas.
23:13The perpetual snows are instantly evaporated.
23:15The perpetual snows are instantly evaporated.
23:40Soon the wall of fire reaches the Amazon, the furthest distance from the point of impact.
23:47The forest spontaneously combusts even before the rock vapor arrives.
23:57Just one day after the impact, the entire planet is covered.
24:01Every living plant or creature is vaporized.
24:05It's been estimated that this vapor would cover the entire globe for almost a year.
24:10It would be as if the sun had come to Earth.
24:15The ocean would start to bubble and boil, and as the water evaporates, the oceans would drop at the rate of five centimeters or two inches every second.
24:24Even the salt deposited on the ocean floor vaporizes, and then the very bottom of the sea melts. Nothing is left untouched.
24:31Nothing is left untouched.
24:32Nothing is left untouched.
24:38One month after the impact, the surface of the world has been sterilized.
24:45The oceans have vanished.
24:46The oceans have vanished.
24:47All that remains is the superheated bedrock.
24:52The oceans have vanished.
24:53The oceans have vanished.
24:54All that remains is the superheated bedrock.
24:59It is thought that an impact of the surface of the surface of the world has been sterilized.
25:06One month after the impact, the surface of the world has been sterilized.
25:09The oceans have vanished.
25:10All that remains is the superheated bedrock.
25:14The oceans have vanished.
25:19All that remains is the superheated bedrock.
25:28It is thought that an impact like this happened six times in the violent past of the Earth's history.
25:39If there was life, it was assumed that it too would have been wiped out, only to begin again.
25:58But now science is not so certain.
26:13Now there is the strong likelihood that life, despite the odds, has survived.
26:19But how could that be possible?
26:40With the oceans gone, where could life have found a sanctuary from the searing heat?
26:44A clue to the answer was found in salt.
26:57These salt lakes in the American Southwest are the remnants of an ancient sea.
27:07Millions of years ago, in the Permian era, the upheaval of the bedrock drained the oceans and left behind these lakes.
27:14Dr. Russell Vreeland is a microbiologist based at Westchester University.
27:21He has been studying the survival strategies of microbes and has come up with some remarkable results.
27:32His study site is a repository for nuclear waste located beside one of the lakes.
27:51The waste site is right in the middle of nearly half a mile of rock salt.
27:55Over time, this salt gradually expands, which is why it makes a good storage medium.
28:02But if nuclear waste can be locked out,
28:07traces of ancient microorganisms could be locked in.
28:13The salt crystals within these worlds have lain untouched and uncontaminated since the ocean dried out millions of years before.
28:24I want to find some areas with the pipe.
28:31And inside the crystals, Dr. Vreeland thought he might find traces of the microbes that lived in that long dead ocean.
28:39Very good example, actually, in my opinion, because we have very nice defined bands and striations.
28:48We have, and each of those represents a tiny, tiny droplet of the Permian ocean that was trapped and has been held in that crystal for 200 million years.
28:58To him, these crystals are as valuable as any gemstone.
29:07Inside the crystal are minute droplets of the seawater trapped within as the salt crystallized.
29:13A tiny hole was drilled so that the drop of water could be released.
29:23Perfectly shaped microorganisms named Bacillus permians were found.
29:28Relics from the past.
29:30But the next finding was truly extraordinary.
29:37For four months, the microbes were fed with a nutrient broth.
29:43They began to divide, then multiply vigorously.
29:46After slumbering through tens of millions of years, they had come awake.
29:51Bacterium that we found in the crystal was neither alive nor dead.
29:59It was in a state of long-term suspended animation.
30:02As a spore, it just literally could do nothing but sit and wait.
30:07The amazing part about a dormancy like that is that they don't need nutrients, they don't produce waste product,
30:13and they have the ability to just sit and wait until conditions are favorable again for survival.
30:22Yet it seems that life did exactly that.
30:26It survived.
30:29What I find amazing is life is really tenacious.
30:32And once it came about, once it evolved, once it was on this planet,
30:37it would have taken a huge event to sterilize the planet.
30:42You would have had to heat the planet literally all over.
30:47And as deep as you possibly could, virtually melt the planet to really destroy the life.
30:54To survive millions of years trapped in salt looks easy compared to the virtual end of the world.
31:12When you have an impact, you have that instant in which all this energy is converted to heat.
31:19But that's only part of it.
31:20You then have the vapor that expands and heats up the atmosphere as well.
31:24So now you are no longer dealing with just the point of impact and the vapor that's created there.
31:35You now have material that's expanding.
31:37Eventually some of that material is expanding and goes out of the atmosphere of the earth, then comes back down.
31:43During the time when it comes back down, it's generating more radiation so that you have the heat of the impact.
31:55Then you have the material, the vapor that heats the atmosphere.
31:58Then you have ejecta that returns to the surface of the earth.
32:01And as it goes through the atmosphere, it will create enough energy to literally fry, completely combust any living organism that would exist.
32:10The total evaporation event that occurred around 4 billion years ago was catastrophic.
32:30Water as well as salt deposited on the ocean floor evaporated.
32:33There are microbes that actually like heat, but not heat like this.
32:54Dr. Sleep of Stanford University looked long and hard at early life's survival capabilities.
32:59He thinks that he has found an answer.
33:02There was a part of the earth where life could sustain itself, and this was deep below the ocean floor.
33:09This graph shows the temperature distribution in the subsurface of the earth.
33:14The red area is the heat from the earth's core.
33:18Nothing can survive in this region.
33:20Green are regions below boiling point.
33:23Blue are regions just below 50 degrees Celsius or 122 Fahrenheit.
33:29Life could survive in this region.
33:30Life could survive in the blue zone.
33:32The Goldilocks zone, as Dr. Sleep calls it.
33:36It has been estimated that the temperatures on the surface of the earth would have reached as high as 2,000 degrees Celsius, over 3,500 Fahrenheit.
33:50What the researchers wanted to know was how deep would the heat penetrate and how fast could it travel down into the earth?
34:00Would the heat from above meet the heat from below?
34:03The heat from above travels slowly and steadily, about one meter or three feet every year.
34:18The simulation showed that there will always be regions where life could survive.
34:28Any organisms that are living deep underground, like one to two kilometers thick, will be fairly safe.
34:35The heat pulse doesn't last long enough for the heat to propagate down to that depth.
34:42It's a little like when you cook a turkey, you can't cook a turkey in your oven in one minute.
34:50If you try to do that, even if you get the outside very hot, the inside will still be cool.
34:56We have the temperatures here.
34:59At the ridge axis, things are relatively hot.
35:02As we get away from the ridge axis, it's relatively cool.
35:05An ordinary organism, you want to be here in the blue.
35:09If life were present 3.8 billion years ago, then the life that we have on earth now would have descended from life that liked higher temperatures.
35:22It was more able to survive high temperature waters and was not photosynthetic.
35:31However, early life needed water, and the water on the surface of the planet was gone.
35:37Was it possible to sustain any sort of life in the rocks deep below the earth's surface?
35:44Here in South Africa, that question has been answered.
35:51Gold brings wealth to a country, but the job of getting that gold is dangerous.
36:00This is one of the deepest man-made shafts in the world.
36:04It drops down over two miles below the surface.
36:07And it's not just the miners who take the long trip below.
36:12Dr. Esther van Heerden of South Africa's Free State University is researching the survival of life deep within the earth.
36:27Her findings and those of the research team are astounding.
36:33Before these shafts were excavated, there was nowhere for scientists to search.
36:41It's dangerous down here.
36:43For every half-mile underground, the temperature goes up by 10 to 15 degrees.
36:50And there is the constant danger from methane.
36:54High levels of this gas would cause an explosion, so it's frequently monitored.
36:59Even so, methane is constantly leaking from the rocks.
37:08So, methane is constantly leaking from the rocks.
37:17Yet life, actually, was found here.
37:23Groundwater is seeping from the rocks, and the surface of the mine wall is covered by a thick film of white and black.
37:43This is a mat of various forms of bacteria, species not found on the earth's surface.
37:48Here they do not use oxygen.
37:54They are anaerobic.
37:56But research shows that many of them still possess the genes for oxygen respiration.
38:01Useless down here.
38:03Perhaps this is evidence that these microorganisms once lived on the surface.
38:09Only to migrate to these depths, perhaps to escape the heat of a total evaporation impact.
38:16Initially, we thought that life only existed two feet from the surface.
38:29We now know that through access through this deep mine subsurface project,
38:34that there are organisms as far as three kilometers underground.
38:38Had we had access to other deep subsurface environments, surely we might find traces of organisms there,
38:45which might indicate the same pattern as we are seeing here.
38:49This deep underground world has been a refuge for life for possibly billions of years.
39:00So far as we know, when life first formed on the planet, it lived in the oceans.
39:11It spread out, and some life forms clearly moved down into the dark subsurface of the earth,
39:17to quietly remain in cracks and in rocks, residing in waters heated by the earth's inner mantle.
39:23If we look at these organisms living in these environments, they have adapted to survive.
39:33Their main aim is just to survive and sustain themselves.
39:36Surely, as things change, new organisms or these organisms will change and adapt
39:42to make sure that life is sustained on the planet no matter what happens.
39:53To survive is life's objective.
39:55And sometime after the total evaporation event, life must have once again returned to the surface.
40:10Immediately after the impact, the planet would have looked like a fireball.
40:15But within only a year, the rock vapor would start to dissipate, and temperatures would begin to drop.
40:23Because of the earth's size and gravity, the evaporated water would not escape into space.
40:28And within only a thousand years, the water vapor would cool and condense, and then fall back as torrential rain.
40:36Once again, the oceans would start to fill.
40:41Once again, the oceans would start to fill.
40:45The rainfall would be as heavy as tropical rain is today, and in only three thousand years, the oceans would have regained their original depth.
40:50The rainfall would be as heavy as tropical rain is today, and in only three thousand years, the oceans would have regained their original depth.
41:15A stage was set for life to return from the deep.
41:30There's always likely to be some area deep in the subsurface of the earth where the heat pulse does not reach.
41:50There's probably an area that's fairly deep, so the organisms that are living there are high temperature organisms to begin with.
41:57These would be the organisms that survived, and these are probably our ancestors and the ancestors of all the other life on the earth.
42:05Those early ancestors of life on this planet had endured against all odds.
42:10They had survived searing heat to once again recolonize the oceans.
42:16From deep within the world, from minute cracks and fissures in the bedrock, the underground life returned to the surface.
42:28Perhaps one day in the far distant future, life may once again be forced to revisit those depths.
42:35How many times this has happened, we perhaps will never know.
42:42For the next two billion years, life remained in the oceans of the world.
42:47Drifting in the waters, taking nutrients, reproducing and dying and living.
42:53The next challenge to life came almost two billion years ago.
43:04And if science is correct, it came not with a mighty impact, but slowly and insidiously.
43:22For millions of years at a time, the planet was shrouded with a thick covering of ice.
43:27Life endured that too, but how?
43:38That answer is locked within the history and the science of the only world we know, the miracle planet.
43:52The magnitude of knowledge has become the соel.
43:53But that's just theáiains of the life.
43:54The point of knowledge of the crew has problems in the two decades, do not do if it is blind.
43:57However, the point of proof is down upon everybody.
43:58For like 10 years, it's tough.
43:59Even when people Rustization out with trees who have been Therefore, take the denimed hypothesis into the world.
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44:04Her state has changed from time before.
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44:07It was two children's findings, the capture.
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44:09Transcription by CastingWords