Venus reveals its true face, recorded in detail for the first time by the radar spacecraft Magellan. Our next-door planetary neighbor turns out to be one of the most bizarre places in the Solar System.
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00:00She's Venus in Blue Jeans
00:20Mona Lisa with a pony tail
00:24She's a walking, talking, work of art
00:29She's a girl who stole my heart
00:33My Venus in Blue Jeans
00:37Is a Cinderella I adore
00:40She is a goddess in nearly every culture.
00:43But to science, Venus is the planet of mystery.
00:59Until recently, virtually nothing was known about Venus
01:07even though it is the nearest planet to Earth.
01:11It is impossible to see the surface of Venus
01:14through its dense layer of clouds.
01:17Nearly identical to the Earth in size,
01:20Venus once held out the tantalizing possibility
01:23of being Earth's twin,
01:25possibly even a source of life,
01:28but no longer.
01:31The spacecraft Magellan just recently completed
01:35a four-year tour of Venus,
01:39piercing its clouds with radar
01:40and mapping the surface in exquisite detail.
01:45What Magellan saw beneath those clouds
01:48was a tortured and alien landscape,
01:52one of the most mysterious places
01:54in the entire solar system.
02:02To study the planets takes us to the very root
02:05of some very fundamental philosophical questions
02:08like, who are we and why are we here
02:11and what is our place in the cosmos?
02:14All the planets in our solar system
02:28were formed four and a half billion years ago
02:31out of the mass of gas, dust, and ice
02:34swirling around the sun.
02:36Farthest away is Pluto.
02:38Then come the watery worlds of Uranus and Neptune.
02:41Then the huge gas giants, Saturn and Jupiter.
02:46Closest to the sun are the four tiny rock planets,
02:49Mars, Earth, Venus, and Mercury.
02:54The Earth and Venus are the only planets
02:57in our solar system that are geologically active.
03:02What other secrets do they share?
03:04There are many things that can be learned
03:11from all the planets
03:12about how atmospheres work
03:14and the behavior of climate through time.
03:15But for geology, the key planet is Venus.
03:19Venus is about the same size of the Earth.
03:21It's right next door to us in the solar system.
03:23It should be made of about the same stuff,
03:25the same proportion of rock and metal as the Earth.
03:27It should be our twin.
03:29Because we can't see its surface,
03:33Venus has always inspired curiosity and speculation.
03:42I've been observing Venus ever since 1934
03:45when I was a boy of 11.
03:46And in that time, I've seen the whole gamut of emotions.
03:50Theories have come.
03:51Theories have gone.
03:52Venus has changed.
03:53The water world, or is it a carboniferous world,
03:55or a desert?
03:56I've seen it all.
03:57Right up to the start of the space age,
04:01Venus was still described as the planet of mystery.
04:04The closest of all the planets,
04:06and yet we knew nothing about the surface at all.
04:07So you could really put there what you liked,
04:09and no one was going to say you were wrong.
04:11And that's exactly what happened until 1610,
04:15when Galileo, using the newly invented telescope,
04:18discovered that Venus appears to wax and wane in the sky,
04:22just as the moon does.
04:23From this observation, he confirmed the heretical theory
04:27that the planets revolve around the sun.
04:31But in the centuries since Galileo,
04:33astronomers have imagined everything on Venus,
04:36from canals to continents.
04:43Thanks to science, and science fiction alike,
04:46many fantastic hopes for Venus remained alive well into this century.
04:50Even in my lifetime, there have been four possible models
04:55of what the surface of Venus might be like.
04:57And the first of these was the most attractive one of all, I think,
05:00the kind of carboniferous model with a primitive life.
05:04A kind of idyllic Venus, warm, but not too warm,
05:07with luxuriant vegetation, swamps everywhere,
05:10and possibly things like dragonflies and amphibians.
05:16On the other hand,
05:17it was thought there might be oceans there,
05:18a kind of marine Venus.
05:22If there are oceans on Venus,
05:24the carbon dioxide in the atmosphere
05:25would have got into the water and fouled it,
05:28and you would have had oceans of soda water.
05:31Number three was oil-rich Venus, seas oil.
05:34Venus is probably endowed with oil,
05:36beyond the dreams of the richest Texas oil king.
05:38And then number four, of course, was the dust theory,
05:41the dust desert theory,
05:42according to which Venus was a desiccated planet
05:44with no water anywhere,
05:46a kind of raging dust storm,
05:48a kind of inferno,
05:49the conventional idea of hell.
05:51In the early days of space exploration,
05:53there were hopes that life would be found on Venus.
05:56Tantalizing, exasperating Venus,
05:59a single significant experiment
06:00can confirm old or create new theories.
06:05Many theories of the Venus environment
06:07have been suggested.
06:09However, new information eliminates
06:10at least some of these theories.
06:13Measurements with radio telescopes show
06:15that there is a region on Venus
06:17where temperatures are greater than 600 degrees Fahrenheit.
06:21It is just possible
06:22that the surface temperature
06:24could then be almost Earth-like,
06:26and life as we know it could exist there.
06:29However, it is more likely
06:31that if there is life on Venus,
06:33it is probably of a type
06:34that we cannot now imagine.
06:37Why do we explore space?
06:39Because we wonder if we really are alone,
06:42or if on some other beautiful world,
06:45perhaps in some other corner of the universe,
06:48there are other thinking beings
06:50asking the same questions that we ask.
06:53Some people believe those questions
06:59have already been answered.
07:05Blessed are the planetary ones
07:08who have at this time
07:10sacrificed peace,
07:13sacrificed friendship,
07:16sacrificed for their salvation.
07:19The Aetheria Society was founded in 1955
07:25by an Englishman, George King.
07:29He was contacted while in his flat
07:32by intelligences from other planets
07:34within this solar system,
07:36and he was told that he was to become
07:38the voice of interplanetary parliament
07:40to make their message known to the world.
07:44Jesus is from Venus in our understanding.
07:51So is the intelligence we refer to as Buddha.
07:56More and more information is going to come to light
07:58which definitely will reveal the fact
08:00that there is advanced life,
08:04intelligent life within this solar system
08:06and on the planet Venus, definitely.
08:08We pray that your light
08:11there would be nothing
08:15that science could bring back to us
08:18that would prove to us
08:20in the Aetheria Society
08:21that life did not exist on Venus.
08:24These intelligences don't live
08:26in a carbon-based body like we do.
08:29They don't breathe
08:30the same type of atmosphere as we do.
08:34They are masters of matter.
08:37It was the space age
08:41which changed all our ideas about Venus.
08:43From having no information at all,
08:45we certainly had a lot,
08:46and many people didn't really like
08:47what they found.
08:50Venus was the target
08:51of the very first interplanetary probe
08:54in 1962.
08:57Far from finding Earth's twin,
09:00Mariner 2 revealed a planet
09:02that is extremely hot,
09:04far hotter than could be explained
09:06simply by its distance from the sun.
09:12It was the height of the Cold War,
09:14and Venus was also becoming
09:16a focus of the Soviet space program.
09:20They were determined to land on Venus.
09:24There was always a sense of competition.
09:28The Soviet government clearly
09:29was supporting such missions
09:31from the point of view of propaganda
09:33and from the point of view
09:35of flexing the muscles.
09:38Venus was considered by them
09:40as a battleground of the Cold War,
09:44one of the battlegrounds.
09:45We scientists were not interested
09:49very much in flexing the muscle.
09:52We were taking this chance
09:53to do our own science,
09:55and it was terribly exciting.
10:00Despite the excitement,
10:01the goal remained elusive.
10:04One lander was sent after another,
10:06each built to withstand
10:08greater heat and pressure.
10:10The Soviets were puzzled
10:11when nothing survived
10:12the atmosphere of Venus.
10:14After endless tests and failures,
10:19they discovered why.
10:20As each probe descended
10:22through the clouds,
10:23it sent back information
10:24revealing a parched planet,
10:26choked with carbon dioxide,
10:29temperatures hot enough
10:30to melt lead,
10:31and atmospheric pressure
10:32that would crush a jumbo jet.
10:34And those mysterious clouds
10:36were actually made
10:37of super-corrosive sulfuric acid.
10:40Eventually, a few heroic super-probes
10:47made it to the surface
10:48and survived there
10:49for up to 65 minutes
10:50before being destroyed.
10:53Finally, in 1975,
10:56a camera aboard a Soviet lander
10:58survived long enough
10:59to send back the first photograph
11:01of the surface of Venus.
11:08We were expecting
11:10at the beginning
11:10to find a twin-sister planet
11:12of our Earth.
11:14Everything which was different
11:16surprised us.
11:18If one would compare
11:19the base knowledge
11:21of Venus
11:23before the space age
11:25and after
11:26this cavalcade
11:29of the spacecraft
11:30landing on Venus,
11:32I would say
11:33we discovered
11:36a completely new world.
11:40If you go to Venus,
11:42you'll be promptly fried,
11:43poisoned,
11:43squashed,
11:44and corroded.
11:46I remember giving a talk,
11:47I think,
11:47at London University
11:48in the 1950s,
11:50and I said then
11:51that quite possibly
11:52Venus as a potential colony
11:53might be more promising
11:55than Mars.
11:56How wrong I was.
11:58With data
11:59from more and more missions,
12:01scientists had to draw up
12:02new images of Venus.
12:04At 900 degrees,
12:06Venus has the hottest
12:08surface temperature
12:09of any planet.
12:10The pressure there
12:11is the same as that
12:12at ocean depths
12:13of about 3,000 feet
12:14on Earth.
12:15There seemed
12:16no chance of life.
12:18How had Venus
12:19so close to Earth
12:20in size and distance
12:22become so different?
12:25When you look
12:25at Venus and the Earth,
12:27they formed at about
12:27the same place
12:28in the solar system,
12:29they're made of
12:29about the same materials,
12:31they're about
12:31the same size.
12:32To a scientist,
12:33this tells you,
12:35okay, you started
12:36at the same point.
12:37Now, shouldn't you end up
12:39at relatively the same point?
12:40And instead,
12:42the two planets
12:42have gone off
12:43in different directions.
12:45Why did that happen?
12:46It's just as if
12:47we put two pies
12:49in the oven
12:50to bake,
12:51and they should have
12:52had the same recipe,
12:54they should have
12:54been put in identically,
12:55they were cooked
12:56for the same time,
12:57out they come,
12:58and they're different.
12:58What happened?
13:02In 1978,
13:07the United States
13:08launched Pioneer Venus,
13:09the most ambitious probe yet.
13:15Pioneer discovered a clue
13:17to the mystery
13:18of why Venus is so hot.
13:21Venus is closer
13:23to the Sun
13:23than the Earth.
13:25That by itself
13:26would increase
13:26its surface temperature
13:27by 90 degrees.
13:29but Venus
13:30is about
13:31800 degrees hotter.
13:34In the atmosphere,
13:36Pioneer found evidence
13:37that although Venus
13:38may once have had oceans,
13:40it had lost
13:41much of its hydrogen,
13:42an essential component
13:44of water.
13:45This could have had
13:46a devastating impact
13:48on its climate.
13:49I was doing some
13:52simple models
13:52of the Earth's climate,
13:54and I decided
13:55to run an experiment
13:56with this model,
13:59move the Earth
13:59to the orbit of Venus,
14:01and see how
14:02the climate changed.
14:03And I got
14:05this amazing result
14:06that as you,
14:09basically,
14:09the model went crazy.
14:11As you move the Earth
14:13towards the Sun,
14:15it gets warmer,
14:16and water evaporates
14:19from the oceans,
14:20and water in the atmosphere
14:22acts as a blanket.
14:24It traps the heat
14:25and causes the surface
14:27to get even warmer.
14:30And that, of course,
14:31causes more water
14:32to evaporate,
14:33and the whole process
14:34runs away.
14:35And I called it
14:37the runaway greenhouse.
14:40Once the water was gone,
14:42Venus was really in trouble.
14:44Made of the same materials,
14:46Venus and the Earth
14:47contain roughly
14:47the same amounts
14:48of carbon dioxide,
14:50the so-called greenhouse gas.
14:54On the Earth,
14:55most of this gas
14:56is dissolved in the seas
14:58and is kept there
14:59as limestone.
15:02On Venus,
15:03it's a different story.
15:06Early in its life,
15:07water on the surface
15:09evaporated.
15:11Carbon dioxide
15:12built up
15:13in its atmosphere.
15:15It formed a barrier
15:16to heat,
15:17like the glass windows
15:18of a greenhouse.
15:21Carbon dioxide
15:22is transparent
15:23to incoming radiation
15:24from the Sun,
15:26which warms
15:26the surface
15:27of the planet
15:28and is re-emitted
15:29in the form of heat.
15:32Some of that heat radiation
15:34escapes back into space,
15:36but the carbon dioxide
15:37also absorbs Sun,
15:39trapping it
15:39in the planet's atmosphere.
15:43As more radiation
15:44from the Sun comes in,
15:46the carbon dioxide
15:47absorbs more heat
15:49and the surface temperature rises.
15:52As the carbon dioxide layer
15:54increases,
15:55so does the temperature.
15:57We've learned
15:58that natural history
15:59is chaotic.
16:00Small difference
16:01in the starting conditions
16:03can produce
16:04enormous differences
16:05later on,
16:06and Venus
16:07and the Earth
16:08are a perfect example
16:09of that.
16:10You've got
16:10a hellish place
16:12over there,
16:13and you've got
16:14this Garden of Eden
16:15here.
16:18While Pioneer
16:19helped explain
16:20the extremely hot
16:21and dry atmosphere
16:22of Venus,
16:23it caused a storm
16:24among geologists.
16:26Using radar
16:27to see through
16:27the clouds,
16:29Pioneer sent back
16:30crude maps
16:30of the surface
16:31of Venus.
16:32These maps
16:33sparked a debate
16:34about heat
16:35within the planet,
16:36the driving force
16:37of all geology.
16:39Over time,
16:40a planet must lose
16:41as much heat
16:42as it generates,
16:43but no one agreed
16:44on how Venus
16:45was losing the heat
16:46from its interior.
16:48There were two theories
16:49that evolved,
16:50both of them
16:51based on our understanding
16:53of how the Earth works.
16:55There was the idea
16:56that Venus
16:56had some kind
16:57of plate tectonics.
17:00Plate tectonics
17:02is the key
17:02to the Earth's geology.
17:04The surface of the Earth
17:05is divided
17:06into huge moving plates,
17:08constantly colliding
17:09and separating.
17:11Where the plates
17:11move apart,
17:13large amounts of magma
17:14well up from deep
17:15inside the Earth
17:16and form new crust.
17:17Almost all of the heat
17:18generated within the Earth
17:20is lost along the vast
17:21boundaries of plates
17:22through plate tectonics.
17:24Many thought Venus
17:25might be losing its heat
17:26in the same way.
17:27The second theory
17:29was that Venus
17:31would lose its heat
17:32not by plate tectonics,
17:34but by great outpourings
17:35of lava
17:36and individual
17:36volcanic centers.
17:43To lose enough heat
17:44through volcanoes,
17:46there would have to be
17:46a great number of them,
17:48all continually active
17:49and erupting.
17:50Both of these theories
17:56evolved very much
17:58by analogy
17:58to what we understood
17:59on the Earth.
18:01What we needed
18:01was a close-up view
18:03of the surface
18:03so that we could see
18:05the individual
18:05geological features.
18:07The only way
18:07we could get that
18:08was to put another
18:09spacecraft in orbit
18:10around Venus
18:11that would give us
18:12images globally
18:14of the surface.
18:15That spacecraft
18:23was to be VOIR,
18:26the Venus Orbiting
18:27Imaging Radar.
18:28Packed with
18:29scientific equipment,
18:30it would map the surface
18:31in fine detail
18:32and answer many
18:33geological questions.
18:35The possibilities
18:36were exciting
18:37and expensive.
18:40We have this wonderful,
18:42fantastic mission
18:43that's going to go
18:44to Venus
18:44and tell us
18:45all about that planet.
18:47We had the spacecraft
18:48approved,
18:50the funding was
18:51about to appear,
18:53the excitement
18:55was rampant
18:55here at the lab,
18:57Reagan got elected,
18:59he came into power,
19:00he came into office,
19:01and suddenly
19:02the funding disappeared.
19:05We were distraught.
19:07Our challenge then
19:08was to make
19:10that mission cheap.
19:12We went to the junkyard,
19:15picked up a lot
19:16of spare parts,
19:17said we will use
19:18those parts
19:19in building
19:19this new mission.
19:21Parker was
19:22the spacecraft manager,
19:24he went to that junkyard
19:25and found a lot
19:26of stuff.
19:27Tell them about it.
19:28I'm not sure
19:29I'd call it a junkyard
19:30really.
19:31It was the storehouse,
19:33if you will,
19:34we had for stuff
19:35that was left over
19:36from previous missions.
19:38We had a high-gain antenna
19:39and other low-gain antennas,
19:41and by combining
19:42leftover equipment
19:43with the spare equipment,
19:45we were able
19:45to put together
19:46a spacecraft
19:47at this much,
19:48much cheaper price.
19:49It took 200 engineers
19:51to downscale the mission
19:52into the more modest
19:54Magellan spacecraft.
19:55We thought that
20:00if we could save
20:01100 million,
20:03Magellan had a reasonable
20:05chance of being funded
20:06and authorized.
20:07We got the 100 million
20:09out,
20:10they said,
20:10that's fine,
20:12gents,
20:13now get another
20:13100 million out.
20:15So this went on
20:16for a period
20:17of about three months
20:18where we incrementally
20:20cut off
20:21100 million dollar chunks
20:22to get the price down
20:24to 250 million.
20:31After being cut
20:32to the bare bones,
20:34this hybrid spacecraft
20:35was left with only
20:36one scientific instrument,
20:38a powerful radar sensor
20:40to map the surface
20:41of Venus.
20:44And then headquarters
20:46says,
20:47you're in.
20:47On May 4th, 1989,
20:55Magellan was launched
20:56aboard the space shuttle
20:57Atlantis.
21:06The launch is kind of
21:08like a berth
21:09in a way
21:10because it separates
21:11a lot of stuff
21:12that went before
21:13from all the good things
21:15that are yet to come.
21:16And I remember
21:17standing there
21:17in the viewing area
21:18and watching shuttles
21:20slowly rise up
21:21and after it was
21:22out of sight
21:23beyond a few
21:25scattered clouds,
21:26I realized
21:27that I hadn't heard
21:28a thing
21:28and tears were
21:29streaming down my face
21:31and I thought,
21:32you know,
21:32it's really in the best,
21:34safest place
21:35it can be now
21:36out in space
21:37where nobody
21:38can drop a hammer
21:39on the solar panels
21:40or burn the batteries
21:41or anything
21:42and that was
21:43an exciting event.
21:47because of where
21:59Venus was in its orbit,
22:01the trip would take
22:01well over a year.
22:06Magellan would have
22:06to circle the sun
22:08one and a half times
22:09before falling into orbit
22:10around Venus.
22:21Magellan had a 15-month cruise
22:23until it got to Venus.
22:25Everybody was
22:26tremendously excited
22:27that we were finally
22:28going to get those answers
22:29that everybody
22:29had been waiting for.
22:31The summer,
22:32right before the
22:33Magellan got to Venus,
22:35everybody laid out
22:36their best theory
22:37of what was going
22:37to happen
22:38in an issue
22:38of a scientific journal.
22:40We were all told,
22:41okay, say what you think
22:43the data is going to prove
22:44and everybody did
22:45and so in anticipation
22:46of that,
22:47you've now published
22:48what you think
22:48is going to be
22:49the right answer
22:49and now you're just
22:51waiting and waiting
22:52for this data
22:53to actually come back.
22:56Not everyone agreed
22:57on what that data
22:58would show.
23:01I like to think
23:02I went in
23:03with an open mind
23:04but I was favoring
23:06a lot of deformation,
23:07a very active planet,
23:09a lot of young volcanism
23:11and the surface
23:13churning up left and right
23:16wherever we would look.
23:17I think a lot of us
23:18in the scientific community
23:20based on the earlier data sets,
23:22especially the Pioneer Venus data,
23:24thought that there was
23:24still a possibility
23:25that there might be
23:26plate tectonics on Venus.
23:28I really expected
23:29that Venus would be
23:31a very active place
23:32and a geological analogy
23:34might be a simmering pot
23:35of porridge
23:35in the sense that
23:37over periods of time
23:38it's very active
23:39and bobbing up and down
23:41here and there
23:41with a lot of activity.
23:45Magellan would provide
23:46the most detailed maps
23:47ever made
23:48of the surface of Venus.
23:51Every orbit,
23:53Magellan's radar
23:54pierced the thick clouds,
23:56imaging the landscape below
23:57in narrow strips
23:58about 15 miles wide
24:00and 10,000 miles long.
24:02By bouncing radio waves
24:05off the surface
24:05and recording their echoes,
24:07geographic features
24:09could be distinguished.
24:10An altimeter then made
24:12precise measurements
24:13of surface elevations
24:14so the terrain
24:15could be mapped.
24:17At the end of each
24:18imaging session,
24:19Magellan turned around
24:20and sent this data
24:22back to Earth
24:22in digital form.
24:24It was received
24:25by NASA's global network
24:27of giant tracking antennas
24:28in California,
24:29Australia,
24:30and Spain.
24:34All of us were
24:35on pins and needles
24:36awaiting the first data
24:38that would allow us
24:39to begin to see
24:40what the surface
24:40really looked like.
24:41We all had our own ideas
24:43for how Venus worked.
24:45Many of them
24:46were in conflict,
24:46but we were simply
24:51terribly anxious
24:54that the mission
24:54would work at all
24:55and very eager
24:57to see who,
24:59if anybody,
24:59would be proven right.
25:01The numerical information
25:02was transformed
25:03into long,
25:04thin images
25:05referred to as noodles,
25:07which would be assembled
25:08into a map
25:09of the entire surface.
25:11A couple of us
25:12went in
25:12at about 4 in the morning
25:13to look at those
25:14first strips,
25:15and you were just
25:15looking at them
25:16and realizing,
25:17I'm seeing these parts
25:18of the planet
25:19that have never been seen
25:20by another person.
25:22And so there's
25:22a sense of awe
25:24just from the,
25:25that you're an explorer,
25:26you're reaching
25:26into new worlds
25:27that no one's seen before.
25:29But in addition,
25:30this is a little nerve-wracking
25:31because is it going to prove
25:32everything that I've said
25:33and published
25:33completely wrong?
25:39We were all proven wrong.
25:42The Venus surface
25:44turned out to be
25:45more mysterious
25:46than any of us
25:47had anticipated,
25:47and all of our ideas,
25:49which after all
25:50had been based
25:50on our understanding
25:51of how the Earth worked,
25:53were tossed out the window.
25:55It was a strange
26:22and alien place,
26:25we were looking at.
26:27There was a river
26:29formed by running lava
26:30longer than the Nile.
26:34There were huge mountain belts.
26:37The sides of the mountains
26:38ran up so steeply
26:40that they were unlike
26:41anything we'd seen on Earth.
26:44We looked searchingly
26:46for features
26:47that we could identify
26:48that looked familiar,
26:50that looked like
26:50something close to home.
26:51We were just blown away
26:59by how different
27:00that planet looked.
27:08Among all the strange
27:10and inexplicable features,
27:12there seemed to be
27:13none of the usual
27:14geological signs
27:15of heat loss,
27:16no telltale ridges
27:17and fault lines
27:18of plate tectonics,
27:20and no large
27:21active volcanoes.
27:22Most of the volcanoes,
27:24in fact,
27:24looked like they had been
27:25dormant for hundreds
27:26of millions of years.
27:28So Venus had to be
27:29losing internal heat
27:31in some unknown
27:32and unearth-like way.
27:34in some unknown
27:35and unearth-like way.
28:04The key to solving the puzzle turned out to be hidden in an unexpected place on the planet's surface.
28:12Like the moon, all solid bodies in the solar system are hit by meteorites.
28:19Such collisions scar the surface with impact craters, which can tell us about its age.
28:26Older land has more craters because it has had more time to accumulate meteorite strikes.
28:32Fresh land is formed when volcanoes erupt, coating the surrounding landscape in a new skin of lava.
28:42This younger land will have fewer impact craters.
28:52When a team of specialists sat down to count, measure, and plot every crater on the surface of Venus,
28:58they were in for the surprise of their careers.
29:02This is the surface of Venus after it has been fully mapped by the Magellan Mission.
29:09And when we had plotted all of the craters on the surface, lo and behold, it was extremely uniform.
29:19They were extremely uniformly distributed across the surface, just totally random, truly astounding.
29:25Such an even distribution of impact craters across the whole planet could only mean one thing.
29:35There was no old or new land.
29:38The whole surface was the same age.
29:41Judging from the number of craters, it was young for a planet only about 500 million years old.
29:47It was quite amazing.
29:50It was incredible to me.
29:51I have never seen anything like this in the 30 years that I've been looking at solid bodies in the solar system.
29:57I've counted craters from Mercury to Triton at Neptune,
30:02and this is the first time I've ever seen a crater population that was completely random.
30:08It just absolutely blew my mind.
30:10No place else in the solar system.
30:13One simple way of explaining this is to have a complete resurfacing of Venus
30:18and then starting all over again, building up the cratering record.
30:21What this actually means is that Venus has turned itself inside and out.
30:26How do you do that?
30:27You know, how do you do that?
30:28For a planet to suddenly resurface itself was unheard of.
30:34More proof would be necessary to convince the scientific establishment.
30:39It was very hard for the community to swallow this because it was so unusual
30:44and it had never happened on any other planet.
30:48So what we did was to run 50,000 Monte Carlo simulations of random point distributions.
30:57Now, Monte Carlo simulation is named after the casinos in Monte Carlo where gambling is a chance.
31:04In other words, it's a random process.
31:06And that's what these are.
31:07So these were computer simulations of random distributions of points.
31:12So we ran 50,000 of these and you could not tell the difference
31:15between the random distributions generated by the computer and the surface of Venus.
31:21We challenged the scientific community when we published this paper
31:24to identify which of these six simulations was really truly Venus.
31:31Five of these are Monte Carlo simulations and one of them is Venus.
31:34And no one could tell them apart.
31:36I couldn't pick out which one was Venus.
31:44And it really dawned on me that the crater population really was random.
31:48We've never seen this on any planet before.
31:51Every other planet has areas that are older and areas that are younger
31:54so that there's a difference in the crater population.
31:56And now here's Venus.
31:58And the whole surface is basically the same age.
32:02This is really confusing.
32:03Explaining the distribution of craters would require a new theory for how Venus works.
32:14Basically, the theory that evolved in my mind at that time
32:18was that this planet today is basically dead as far as its surface is concerned.
32:25But the net result is that the interior is heating up and getting hotter and more active
32:31like a pot of porridge if you turn up the heat.
32:35And eventually, the surface will become disrupted
32:38and it will catastrophically sink into the interior.
32:42And then there will be a period of totally catastrophic surface volcanism
32:55with time of flame and you have virtually a complete magma ocean
33:03on the entire surface of the planet.
33:05This extracts so much heat from the interior of the planet
33:10that the interior cools off
33:13until the point that it is sufficiently cool
33:17that again the planet dies
33:20and starts to form a solid surface
33:24very quiet and peaceful
33:26for 500 million years
33:28and looks like the planet is totally dead
33:31with no volcanism, earthquakes
33:34or other activity of that sort.
33:37But it then heats up in the interior
33:39until you're ready for another catastrophe.
33:42As the interior heats up
33:44eventually this process repeats.
33:47The whole surface founders and sinks into the interior
33:51and this episodicity repeats again.
33:55When this idea was first presented
33:58some of the noted scientists
34:00some of whom are on this program
34:03laughed openly in the audience.
34:09My reaction was
34:11this is one of the most implausible theories I've ever heard.
34:17When I first heard what Don had to say
34:20I really didn't like it very much.
34:22I don't like catastrophic explanations basically.
34:27There used to be lots of such things for the Earth
34:29and most of them have come undone
34:31and it seemed to me
34:32just exactly the same thing going on on Venus.
34:37Don Turcotte had struck a raw nerve.
34:41His theory reopened
34:42a 150-year-old debate
34:44at the heart of geology.
34:47Early geological theory
34:49was influenced by the Bible
34:50and the idea that everything you see on Earth
34:53mountains, canyons, oceans
34:56were formed suddenly
34:58often through biblical catastrophes
35:00like Noah's flood.
35:04Catastrophism dominated science
35:06until it was challenged in the 19th century
35:08by the theory of uniformitarianism.
35:11This argued that all geological processes
35:14work slowly and continuously.
35:16that landscapes take millions of years to form
35:20with no dramatic global upheavals
35:23and that what you see today
35:25is simply part of an ancient and ongoing process.
35:30Since this theory best explains how the Earth works
35:34all geologists are now trained as uniformitarians.
35:38I'm fundamentally a uniformitarianist.
35:47I think that that's the right way to start.
35:51And so far from what I've seen on Venus
35:54there's nothing which convinces me
35:56that I'm wrong in taking that approach.
35:59I may be
36:00but I'm to be convinced.
36:02Dan McKenzie's model doesn't allow for the planet
36:09to swing between extremes
36:11from being dormant to violently active.
36:15Instead, everything must behave
36:17in a steady, uninterrupted way.
36:21He believes that heat generated within the planet
36:24must be escaping across a very thin outer skin
36:27or lithosphere.
36:29I think the planet is now losing heat
36:33really quite rapidly
36:34probably as rapidly as the Earth.
36:36Venus has all kinds of features on the surface
36:39which are just like the features on the Earth
36:41which are active now.
36:42And I bet it's active.
36:44In contrast to McKenzie's thin lithosphere planet
36:48which allows heat to escape continuously
36:50Turcotte's catastrophic model of Venus
36:53predicts that for 500 million years
36:56the surface of the planet looks dead.
36:59The lithosphere thickens
37:01trapping and bottling up the heat inside
37:04until suddenly the whole planet convulses
37:07releasing its heat
37:08before shutting down again.
37:14Knowing which theory best explained Venus
37:17depended on whether its lithosphere
37:19was thick or thin.
37:22There was a great debate
37:23over the thickness of the lithosphere on Venus.
37:26There were two opposing camps
37:27one favoring a very thin lithosphere
37:29a lot of heat coming out
37:31one favoring a thick lithosphere.
37:33The key data to resolve that question
37:36everyone thought was the gravity data.
37:40Every part of a planet
37:42has a minutely different gravitational pull
37:45dependent on the density of the rock
37:47at each place.
37:49When a spacecraft passes close enough
37:51to a mountain
37:52it's very slightly speeded up
37:54by the additional gravitational pull
37:56of the mass of the mountain.
37:59In theory
37:59this gravity data could reveal
38:01what lies underneath the surface
38:03whether the weight of the mountain
38:05is being passively supported
38:07on a thick lithosphere
38:08or actively pushed up
38:10on a thin lithosphere
38:11by a plume of hot rocks.
38:13But Magellan had not been designed
38:19to gather this data.
38:21Its orbit was elliptical
38:23so most of the time
38:24it was too far from the surface
38:26to sense minute changes
38:28in gravitational pull.
38:32Magellan would have to slow itself down
38:34into a tight circular orbit
38:36closer to the surface of Venus
38:38and the only way to do that
38:40was to use the atmosphere of Venus
38:43as a breaking mechanism.
38:45But this maneuver was risky
38:47and if something went wrong
38:49it could destroy the whole spacecraft.
38:51When we first brought it up
38:58to NASA
38:59as a concept
39:01for an extended mission
39:02they thought we were crazy.
39:03You know
39:03they looked at us like
39:04we're nuts
39:05like Dan was nuts
39:06but Dan persisted.
39:14When we first started
39:15firing the thrusters
39:17to lower the spacecraft
39:18down into the atmosphere
39:19I realized at that point
39:21it could very easily burn up
39:23in the atmosphere
39:24and people would look at me
39:26like I was crazy.
39:36It worked beautiful.
39:38Things went much smoother
39:39than many of the other phases
39:40of the mission.
39:43Magellan was very robust
39:45and we were able to work around
39:47all the many problems we had
39:48and then in the extended mission
39:51we got this beautiful gravity data
39:53pretty much free.
39:58As it turned out
40:00the gravity data
40:01was open to interpretation.
40:04I certainly hoped
40:05that it would demonstrate
40:07that the lithosphere was thick
40:09but it really demonstrated
40:12it far beyond
40:13my wildest expectations.
40:16I mean it seems to me
40:16that the data is quite clear
40:18and that that is nonsense.
40:20The lithosphere is thin
40:21not thick.
40:23I think the thermal lithosphere
40:25is 200 or 300 kilometers thick.
40:27I think it's relatively thin
40:28on the order of 100 kilometers or less.
40:30As much as 200 kilometers thick.
40:32The thickness of the lithosphere
40:33on Venus today
40:34is close to 300 kilometers.
40:36It's quite clear
40:38from the gravity data
40:39that it is not 300 kilometers thick.
40:41That it is no more than 100 kilometers
40:43over the whole planet.
40:46The reason why
40:47I think Venus
40:48is losing the heat
40:49is because I can see
40:51the convection
40:52in the gravity data.
40:53And it's thermal convection
40:55which is very vigorous.
40:57It's at least
40:57as vigorous as the Earth.
40:59And it's bringing up
41:00a great deal of heat
41:01which is somehow being lost.
41:03Now exactly how it's lost
41:04we don't know
41:04but we can actually
41:05see the heat moving.
41:07Of course
41:07a good geophysicist
41:08can model gravity
41:10in such a way
41:11that he or she
41:12can get any answer
41:13that they are looking for.
41:15Gravity data
41:16have an inherent ambiguity
41:19in the sense that
41:21there are a variety
41:22of models
41:24for the interior
41:25of a planet
41:26that can satisfy
41:27the same gravity field.
41:29So even though
41:31we know the gravity field
41:32much better now
41:33on Venus
41:33it hasn't answered fully
41:37the debate
41:38that's been going on.
41:39To help solve
41:42the mystery
41:42of Venus' lithosphere
41:43other scientists
41:44thought that
41:45those incredibly
41:46steep mountains
41:47they had seen
41:48in the Magellan images
41:49might hold clues.
41:51On Earth
41:52high mountain ranges
41:53actually spread out
41:54over millions of years
41:55with the downward
41:56pull of gravity
41:57unless
41:58other geological forces
42:00pushed them up.
42:02Geologists thought
42:02that on Venus
42:03where the temperature
42:04is 900 degrees
42:06or halfway
42:06to the melting point
42:07of rock
42:08this sagging process
42:09should happen
42:10even faster.
42:12Prior to Magellan
42:13due to the fact
42:14that we knew
42:14it was so hot
42:15on Venus
42:16we thought
42:16that the rocks
42:17at the surface
42:17would behave
42:18more plastically
42:19sort of more
42:20like silly putty
42:20than like solid rock
42:22the way we think of it
42:23like the rocks
42:24that I'm sitting on.
42:26Now that would mean
42:27that high mountain ranges
42:28on Venus
42:29unless something
42:30was holding them up
42:31would start relaxing away
42:32just due to the force
42:33of gravity
42:34they would sort of
42:34flow outward
42:35trying to flatten
42:36themselves out
42:37under this great force.
42:39But after 500 million years
42:41the mountains
42:42on Venus
42:42are not relaxing
42:43so what is
42:44holding them up?
42:46We went
42:47and
42:48took some rocks
42:50that were very
42:51very similar
42:52to the rocks
42:53that you find
42:53in Venus
42:54and we baked them out
42:56so they were bone dry
42:57because we know
42:57that the surface
42:59of Venus
42:59is dry
43:01it's so hot
43:02there's no water
43:02there
43:03the rock
43:04is dry
43:04and then we measure
43:06how strong they are
43:07after they've been
43:10baked out
43:10with samples
43:11that haven't been
43:12baked out
43:13and that way
43:13we can compare
43:14how strong they are
43:16in Venus
43:16with how strong
43:18they are
43:18on Earth.
43:20The baked Venus
43:21like sample
43:22and the unbaked
43:24Earth rock
43:24are then subjected
43:25to intense heat
43:26and pressure
43:27as on the surface
43:28of Venus.
43:29The behavior
43:30of the rocks
43:31under such extreme
43:32conditions
43:33was startling.
43:35It was a great surprise
43:37to see how much
43:37difference in strength
43:38there was.
43:39It said straight away
43:40that the rocks
43:41that make up
43:42the surface of Venus
43:43are much stronger
43:44than everybody
43:44had thought before.
43:46The dried out
43:47Venus like sample
43:48on the left
43:49still maintained
43:50its original shape
43:51after heat
43:52and pressure
43:52had been applied
43:53but the undried
43:55Earth rock
43:55on the right
43:56deformed
43:57under the intense load.
43:59What this means
44:00is that the presence
44:02of water
44:02within the rock
44:03causes a weakening
44:05of the minerals
44:06within the rock
44:06and if you take
44:07that water
44:08out of the rock
44:09the minerals
44:10are much stronger
44:11and the rock
44:12becomes much more rigid.
44:13they are about
44:19up to a factor
44:19of ten
44:20times stronger
44:21than they are
44:21on Earth.
44:24All of a sudden
44:25we're left
44:25with a situation
44:26where we understand
44:27why these mountains
44:29are so high
44:30how the slopes
44:31stay so steep
44:32on the surface
44:33of that planet
44:34in a way
44:35that we never
44:35understood before.
44:36What did this mean
44:41for the thickness
44:42of Venus's lithosphere?
44:48Mackwell's data
44:49really shows
44:50that the mountains
44:50don't have to slump away
44:52when you have
44:53a thin lithosphere
44:53and this is just
44:55really critical
44:56and exciting
44:56for supporting
44:57a thin lithosphere
44:58idea on Venus.
45:00Now that we know
45:01how strong
45:02the rocks of Venus
45:03can be
45:03even under
45:05the hot conditions
45:05at the surface
45:06of Venus.
45:08It helps us also
45:09to understand
45:10how Venus
45:10could have
45:11a thick lithosphere.
45:13The problem is
45:14that to have
45:15such strong rocks
45:17making up
45:17the surface
45:18of a planet
45:18it's a bit like
45:19having a rigid
45:21top on a cake
45:22you're baking.
45:23You know,
45:24you try and
45:25look at the cake
45:25and you may
45:26tap the surface
45:27that doesn't tell you
45:28whether the interior
45:28of the cake
45:29is liquid or solid.
45:31And so
45:32to try and
45:33come up with
45:34arguments about
45:34what's going on
45:35inside Venus
45:36on the basis
45:37of what you see
45:38on the surface
45:39may be very misleading.
45:42And so
45:42I don't think
45:44that our data
45:44really clearly
45:46establishes
45:46who's right
45:47in the thin
45:48thick lithosphere
45:48argument.
45:51While the rock
45:52data was
45:53inconclusive
45:53all those
45:54impact craters
45:55had begun
45:56to change
45:56the minds
45:57of some
45:57scientists.
46:05The problem
46:06is that
46:06most of the
46:07craters
46:07are pristine
46:08untouched
46:09since the day
46:10they were formed.
46:11There's been
46:12virtually no
46:13volcanic activity
46:14spilling fresh
46:15lava over them
46:16or tectonic
46:17movement crushing
46:18or distorting them.
46:20So how could
46:20this be explained
46:21by a uniformitarian
46:23model where
46:24geological activity
46:25should be continuous?
46:30I had always
46:31had this one
46:32picture of Venus
46:32a picture of
46:34Cleopatra Patera
46:35an impact crater
46:36on top of the
46:37mountain range
46:38Maxwell-Montes.
46:39Here's this
46:40mountain range
46:40that's miles
46:41and miles high
46:42it's intensely
46:43deformed
46:44it's been broken
46:45and crunched up
46:45and yet on top
46:47of it
46:47is this
46:48perfectly pristine
46:49preserved
46:50impact crater.
46:51This is a huge
46:52problem.
46:53It was a problem
46:55that the
46:55uniformitarians
46:56couldn't explain.
46:59On an active
47:00planet
47:00many of the
47:01craters would also
47:02be severely
47:03distorted
47:03not perfectly
47:05preserved.
47:07I'd been looking
47:08at this picture
47:09for months and
47:09months off and
47:10on
47:10and finally
47:11it just wore me
47:12down
47:13it just ground
47:13me down
47:14and finally
47:15just had to say
47:15look I was wrong
47:17this business of
47:19uniformitarianism
47:19just isn't working
47:20and I just got to
47:22change and to go
47:24with what I think
47:25is right now
47:25and admit it
47:26and that is that
47:27Venus has undergone
47:28a catastrophic change
47:29in the last few
47:29hundred million years.
47:32But the craters
47:33have not changed
47:34everyone's mind.
47:37At the moment
47:38catastrophism is
47:39the only explanation
47:40of the craters
47:42which anyone
47:43has offered
47:43which works.
47:45I don't like
47:46catastrophes.
47:47I don't know
47:48what the answer is.
47:48I don't know
47:49how to explain that
47:50by uniformitarian
47:51argument
47:51but I haven't
47:52given up trying.
47:56Unable to resolve
47:57the debate
47:58and with its power
47:59fading
48:00on October 12th
48:011994
48:02Magellan plunged
48:05into the atmosphere
48:06of Venus.
48:06We all knew
48:10that it had to
48:10come to an end.
48:11The spacecraft
48:12has done a tremendous
48:13job.
48:13I think we all
48:14had a tremendous
48:14amount of pride
48:15with the mission
48:16and with the data
48:17that we've been
48:18able to return
48:18but when the
48:20spacecraft was
48:21supposed to have
48:22come from behind
48:23the planet
48:23the last time
48:24and we couldn't
48:24lock up on it
48:25we all just
48:26looked at each other
48:27all of our eyes
48:28got a little wet
48:29and I think we
48:30kind of hugged
48:31each other
48:31for the last time
48:32and everybody
48:33kind of turned
48:34and walked away
48:35knowing that
48:37it was over.
48:38That startling
48:38announcement on
48:39television that
48:40hey Magellan
48:41had gone in
48:42caused me to get up
48:43and I saluted
48:44and tears came
48:45out of my eyes.
48:47I feel incredibly
48:49sad that we won't
48:49get back anything
48:51else from Magellan
48:51and there were
48:54a lot of people
48:54who were very sad
48:56and very emotional
48:56over the fact
48:57that this satellite
48:59this friend of ours
49:00was gone.
49:02I think of it
49:03as a friend.
49:04I think of it
49:04as something that
49:05has not only
49:06helped our careers
49:08along but in a lot
49:09of ways has really
49:10made our career
49:11like a friend would
49:12do.
49:16Although Magellan
49:17is gone now
49:18speculation about
49:20Venus continues
49:21just as it always
49:23has.
49:25The big question
49:26now that many
49:27people are looking
49:27at in the planetary
49:29community is
49:29is Venus dying
49:31is it dead
49:33or is it going
49:35to recycle
49:36and come back
49:37to life
49:37in the future?
49:38The only way
49:39we can resolve
49:40those kinds of
49:41questions is to
49:41go back to Venus.
49:43It would be good
49:44if we could
49:45cooperate with
49:47Americans
49:47you know
49:48not just to
49:49compete.
49:50I would love
49:51there to be
49:51another probe
49:52to Venus
49:52in my lifetime
49:53and the thing
49:54I would really
49:55like it to do
49:55is to put down
49:57seismometers
49:58so that we could
49:59see as if
50:00there were Venus
50:00quakes.
50:01But will there
50:02be another
50:02mission to
50:03Venus?
50:04I think the
50:06end of Cold War
50:07would complicate
50:09even American
50:11space program.
50:12It is not
50:13anymore driven
50:14by syndrome
50:15of space
50:16rays.
50:18Whether they
50:19will be able
50:20to excite
50:20taxpayers
50:21with more
50:23and more
50:24projects
50:25more and more
50:26launches
50:26it's doubtful.
50:30the dazzling
50:31light of Venus
50:32continues to
50:33beckon to
50:34scientists.
50:43The more
50:44we know
50:44the more
50:45enticing
50:46the mystery
50:47of our
50:47closest
50:48planetary
50:48neighbor.
50:51While the
50:52Magellan
50:52mission answered
50:53many of our
50:54questions about
50:55Venus
50:55it also gave
50:57us many
50:57more
50:58to ask.
51:00Venus
51:01goddess
51:03of love
51:04that you
51:05are
51:06surely
51:08the things
51:09I ask
51:11can't be
51:12too great
51:14a task
51:15Well,
51:16I would
51:17say that
51:18I really
51:19do hope
51:20I have solved
51:21the problem
51:21of Venus.
51:22one might
51:24push me
51:25to say
51:25I have
51:26but there
51:27is always
51:28that queasy
51:29feeling
51:30that that
51:31kind of
51:31statement
51:32in science
51:32might come
51:33back to
51:33haunt one.
51:43Educators,
51:44educational
51:44institutions
51:45and organizations
51:46can purchase
51:47this and many
51:48other NOVA
51:48programs
51:49for $19.95
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51:53call
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51:57She's Venus
52:01in blue jeans
52:03Mona Lisa
52:05with a ponytail
52:06She's a walking
52:10talking
52:10work of art
52:12She's the girl
52:14who stole my heart
52:16My Venus
52:17in blue jeans
52:20is the Cinderella
52:22I adore
52:23She's my very special
52:27angel too
52:29A fairy tale
52:31come true
52:32They say there's
52:34seven wonders
52:35in the world
52:37But what they say
52:39is out of date
52:41There's more than
52:43seven wonders
52:44in blue
52:45I just met
52:48number eight
52:50My Venus
52:52in blue jeans
52:54NOVA is a production
52:57of WGBH Boston