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We know more about other planets than our own,
and today, I want to show you a new type of robot
designed to help us better understand our own planet.
It belongs to a category
known in the oceanographic community as an unmanned surface vehicle, or USV.
And it uses no fuel.
Instead, it relies on wind power for propulsion.
And yet, it can sail around the globe for months at a time.
So I want to share with you why we built it,
and what it means for you.
A few years ago, I was on a sailboat making its way across the Pacific,
from San Francisco to Hawaii.
I had just spent the past 10 years working nonstop,
developing video games for hundreds of millions of users,
and I wanted to take a step back and look at the big picture
and get some much-needed thinking time.
I was the navigator on board,
and one evening, after a long session analyzing weather data
and plotting our course,
I came up on deck and saw this beautiful sunset.
And a thought occurred to me:
How much do we really know about our oceans?
The Pacific was stretching all around me as far as the eye could see,
and the waves were rocking our boat forcefully,
a sort of constant reminder of its untold power.
How much do we really know about our oceans?
I decided to find out.
What I quickly learned is that we don't know very much.
The first reason is just how vast oceans are,
covering 70 percent of the planet,
and yet we know they drive complex planetary systems
like global weather,
which affect all of us on a daily basis,
sometimes dramatically.
And yet, those activities are mostly invisible to us.
Ocean data is scarce by any standard.
Back on land, I had grown used to accessing lots of sensors --
billions of them, actually.
But at sea, in situ data is scarce and expensive.
Why? Because it relies on a small number of ships and buoys.
How small a number was actually a great surprise.
Our National Oceanic and Atmospheric Administration,
better known as NOAA,
only has 16 ships,
and there are less than 200 buoys offshore globally.
It is easy to understand why:
the oceans are an unforgiving place,
and to collect in situ data, you need a big ship,
capable of carrying a vast amount of fuel
and large crews,
costing hundreds of millions of dollars each,
or, big buoys tethered to the ocean floor with a four-mile-long cable
and weighted down by a set of train wheels,
which is both dangerous to deploy and expensive to maintain.
What about satellites, you might ask?
Well, satellites are fantastic,
and they have taught us so much about the big picture
over the past few decades.
However, the problem with satellites
is they can only see through one micron of the surface of the ocean.
They have relatively poor spatial and temporal resolution,
and their signal needs to be corrected for cloud cover and land effects
and other factors.
So what is going on in the oceans?
And what are we trying to measure?
And how could a robot be of any use?
Let's zoom in on a small cube in the ocean.
One of the key things we want to understand is the surface,
because the surface, if you think about it,
is the nexus of all air-sea interaction.
It is the interface through which all energy and gases must flow.
Our sun radiates energy,
which is absorbed by oceans as heat
and then partially released into the atmosphere.
Gases in our atmosphere like CO2 get dissolved into our oceans.
Actually, about 30 percent of all global CO2 gets absorbed.
Plankton and microorganisms release oxygen into the atmosphere,
so much so that every other breath you take comes from the ocean.
Some of that heat generates evaporation, which creates clouds
and then eventually leads to precipitation.
And pressure gradients create surface wind,
which moves the moisture through the atmosphere.
Some of the heat radiates down into the deep ocean
and gets stored in different layers,
the ocean acting as some kind of planetary-scale boiler
to store all that energy,
which later might be released in short-term events like hurricanes
or long-term phenomena like El Niño.
These layers can get mixed up by vertical upwelling currents
or horizontal currents, which are key in transporting heat
from the tropics to the poles.
And of course, there is marine life,
occupying the largest ecosystem in volume on the planet,
from microorganisms to fish to marine mammals,
like seals, dolphins and whales.
But all of these are mostly invisible to us.
The challenge in studying those ocean variables at scale
is one of energy,
the energy that it takes to deploy sensors into the deep ocean.
And of course, many solutions have been tried --
from wave-actuated devices
to surface drifters
to sun-powered electrical drives --
each with their own compromises.
Our team breakthrough came from an unlikely source --
the pursuit of the world speed record in a wind-powered land yacht.
It took 10 years of research and development
to come up with a novel wing concept
that only uses three watts of power to control
and yet can propel a vehicle all around the globe
with seemingly unlimited autonomy.
By adapting this wing concept into a marine vehicle,
we had the genesis of an ocean drone.
Now, these are larger than they appear.
They are about 15 feet high, 23 feet long, seven feet deep.
Think of them as surface satellites.
They're laden with an array of science-grade sensors
that measure all key variables,
both oceanographic and atmospheric,
and a live satellite link transmits this high-resolution data
back to shore in real time.
Our team has been hard at work over the past few years,
conducting missions in some of the toughest ocean conditions
on the planet,
from the Arctic to the tropical Pacific.
We have sailed all the way to the polar ice shelf.
We have sailed into Atlantic hurricanes.
We have rounded Cape Horn,
and we have slalomed between the oil rigs of the Gulf of Mexico.
This is one tough robot.
Let me share with you recent work that we did
around the Pribilof Islands.
This is a small group of islands deep in the cold Bering Sea
between the US and Russia.
Now, the Bering Sea is the home of the walleye pollock,
which is a whitefish you might not recognize,
but you might likely have tasted if you enjoy fish sticks or surimi.
Yes, surimi looks like crabmeat, but it's actually pollock.
And the pollock fishery is the largest fishery in the nation,
both in terms of value and volume --
about 3.1 billion pounds of fish caught every year.
So over the past few years, a fleet of ocean drones
has been hard at work in the Bering Sea
with the goal to help assess the size of the pollock fish stock.
This helps improve the quota system that's used to manage the fishery
and help prevent a collapse of the fish stock
and protects this fragile ecosystem.
Now, the drones survey the fishing ground using acoustics,
i.e., a sonar.
This sends a sound wave downwards,
and then the reflection, the echo from the sound wave
from the seabed or schools of fish,
gives us an idea of what's happening below the surface.
Our ocean drones are actually pretty good at this repetitive task,
so they have been gridding the Bering Sea day in, day out.
Now, the Pribilof Islands are also the home of a large colony of fur seals.
In the 1950s, there were about two million individuals in that colony.
Sadly, these days, the population has rapidly declined.
There's less than 50 percent of that number left,
and the population continues to fall rapidly.
So to understand why,
our science partner at the National Marine Mammal Laboratory
has fitted a GPS tag on some of the mother seals,
glued to their furs.
And this tag measures location and depth
and also has a really cool little camera
that's triggered by sudden acceleration.
Here is a movie taken by an artistically inclined seal,
giving us unprecedented insight into an underwater hunt
deep in the Arctic,
and the shot of this pollock prey
just seconds before it gets devoured.
Now, doing work in the Arctic is very tough, even for a robot.
They had to survive a snowstorm in August
and interferences from bystanders --
that little spotted seal enjoying a ride.
(Laughter)
Now, the seal tags have recorded over 200,000 dives over the season,
and upon a closer look,
we get to see the individual seal tracks and the repetitive dives.
We are on our way to decode what is really happening
over that foraging ground,
and it's quite beautiful.
Once you superimpose the acoustic data collected by the drones,
a picture starts to emerge.
As the seals leave the islands and swim from left to right,
they are observed to dive at a relatively shallow depth of about 20 meters,
which the drone identifies is populated by small young pollock
with low calorific content.
The seals then swim much greater distance and start to dive deeper
to a place where the drone identifies larger, more adult pollock,
which are more nutritious as fish.
Unfortunately, the calories expended by the mother seals
to swim this extra distance
don't leave them with enough energy to lactate their pups back on the island,
leading to the population decline.
Further, the drones identify that the water temperature around the island
has significantly warmed.
It might be one of the driving forces that's pushing the pollock north,
and to spread in search of colder regions.
So the data analysis is ongoing,
but already we can see that some of the pieces of the puzzle
from the fur seal mystery
are coming into focus.
But if you look back at the big picture,
we are mammals, too.
And actually, the oceans provide up to 20 kilos of fish per human per year.
As we deplete our fish stocks, what can we humans learn
from the fur seal story?
And beyond fish, the oceans affect all of us daily
as they drive global weather systems,
which affect things like global agricultural output
or can lead to devastating destruction of lives and property
through hurricanes, extreme heat and floods.
Our oceans are pretty much unexplored and undersampled,
and today, we still know more about other planets than our own.
But if you divide this vast ocean in six-by-six-degree squares,
each about 400 miles long,
you'd get about 1,000 such squares.
So little by little, working with our partners,
we are deploying one ocean drone in each of those boxes,
the hope being that achieving planetary coverage
will give us better insights into those planetary systems
that affect humanity.
We have been using robots to study distant worlds in our solar system
for a while now.
Now it is time to quantify our own planet,
because we cannot fix what we cannot measure,
and we cannot prepare for what we don't know.
Thank you.
(Applause)
コツ：単語をクリックしてすぐ意味を調べられます！

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B1 中級 米

【TED】How a fleet of wind-powered drones is changing our understanding of the ocean | Sebastien de Halleux

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林宜悉 2018 年 12 月 12 日 に公開

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