NOVA

NARRATOR: We live in a built world.

Engineering and technology, built upon innovations and inventions, stretching back thousands of years.

Some of our creations, like machines, boost our bodies' abilities.

Others help us reach outside our comfort zones.

We have left an indelible mark on the planet.

And now the time has come to use our skills to make a better world.

WORKER: ...two, three, lower.

NARRATOR: Like inventing a new way to fly, electrically.

Or a device that can smell... ANN PERSON: I get very excited when technology works.

NARRATOR: ...to save food from going to waste.

THARINDU MADDUMA: Food waste is enormous global problem.

NARRATOR: Creating a machine...

RESEARCHER: Rob, I'm going in.

NARRATOR: ...to heal coral reefs.

ARAN MOONEY: How do we fix the environment that's sort of dying in front of us?

NARRATOR: Or even combining a traditional work of art... LEWIS STETSON ROWLES: We see this amazing opportunity to use pottery.

NARRATOR: ...with modern chemistry... NAVID SALEH: Could you actually make something like that?

Do you have something similar?

NARRATOR: ...to provide clean drinking water.

I made a shape similar to that.

NARRATOR: "Building Stuff: Change It!"

Right now, on "NOVA."

NARRATOR: Human beings have been changing our surroundings for thousands of years.

The signs are written on the land itself.

We're builders and makers.

And the evidence is plain to see.

ADAM STELTZNER: Our whole lives are constructed.

We live in the modern world in a very altered environment.

And all of that alteration starts and finishes with engineering.

ANDREA ARMANI: Engineering can transform a community by bringing power, bringing water, growing food.

DEB CHACHRA: Taking sewage away, the power grid, telecommunications, these are all engineering systems that are not about making any one of us smarter or stronger or faster, but making us, collectively, have more agency and more capacity.

NARRATOR: But building the modern world has come with steep costs and changes to more than just the land, like altering the chemical composition of our atmosphere.

But now there's a new generation that wants to engineer a cleaner planet.

So, as an engineer, when you see the world as it is, you begin to think, "How could we make it better?"

So that's our job, to take the world as it is and make it better.

Everyone's engineering background, it comes from that purpose of saying, "I want to solve a problem that just changes the world."

NARRATOR: One daunting challenge we face today is to reduce the carbon emissions caused by burning fossil fuels.

Electrifying transportation offers some hope.

On the ground, cars, buses, trucks and trains are gradually making the switch.

But what about in the air?

Is there a way to go green in flight?

At Joby Aviation in Marina, California, engineers think so.

They're testing a new kind of aircraft.

WILSON: So, today, uh, Joby's flight test team is putting the aircraft through its paces, flying range and endurance missions.

NARRATOR: The aircraft is a hybrid-- like a helicopter, able to take off vertically, but also, like an airplane, able to fly horizontally at high speeds.

And it's completely electric.

ARMANI: The challenge is, you know, how do we make a personal helicopter?

How do we make them sustainable?

Right, we don't want to bring more jet fuel into the world.

WILSON: It is routine for us to fly three times a day, cruising around at about 100 knots.

NARRATOR: Joby's ultimate dream is to deploy the aircraft in cities around the world as flying taxis, reducing congestion on the ground.

Today they're in the final testing stages of their latest prototype.

But despite promising results, they're not taking chances with humans on this round.

WILSON: There's actually nobody on board the aircraft while it's in flight.

The pilots are simply sat on the ground in the ground control station, flying the aircraft remotely.

NARRATOR: Technically, it's known as an EVTOL, Electric Vertical Take Off and Landing.

But it's also capable of level, forward flight.

As we're going through our airspeed expansion, we are testing a, a certain airspeed, performing a bunch of tests to make sure our aircraft is stable, and then expanding into different airspeed regimes all the way to fully wing-borne flights.

NARRATOR: This day's testing is winding down.

A sudden tilt on touchdown is quickly corrected by the remote pilot.

Something to tweak for future flights.

WILSON: Our analysts look at the data after the flight to make sure that the aircraft is performing exactly as we expect it to.

NARRATOR: As Joby engineers work to realize their dream, significant engineering challenges remain before regular passenger flights become a reality.

DARAIO: As you're trying to develop transportation devices, you really need to understand the environment in which these systems need to operate and iterate the engineering design, the components, the testing specifically to those needs.

NARRATOR: Today, it's not uncommon to see helicopters in city skies.

But they have drawbacks.

They're noisy, the learning curve to fly them is steep, they have limited forward speed, and they burn fossil fuels.

Joby's design is an attempt to address all of those problems.

VALERO-CUEVAS: You have identified a problem.

Can you make an airplane that uses propellers like a helicopter but doesn't have that noise?

Well, you've dreamt it up.

The question is, how do you actually bring it into existence?

WORKER: All right, one, two, three, lower.

NARRATOR: One of the biggest challenges has been to invent a new propulsion system.

The idea was to design a vehicle for four passengers and a pilot that can rise straight off the ground and then somehow transition to fly like an airplane.

Joby's solution-- six electric motors that can individually pivot, propelling the vehicle up to 200 miles per hour, eliminating fossil fuels and reducing noise, a critical improvement if they have any hope of widespread adoption.

That's what gives the aircraft its unusual profile.

Six smaller propellers that are quieter than a single helicopter blade.

But because they're small, everything depended on finding the right propeller shape, a surprisingly complicated problem, part art and part science, with much of the know-how handed down since the early pioneers of powered flight.

These propellers may seem wholly modern.

But if we trace their evolution, we can see clear connections to the past.

Leonardo da Vinci's notebooks contain one of the most famous early conceptualizations of a device resembling the modern propeller.

Da Vinci, in turn, may have been inspired by the Greek philosopher Archimedes and his screw-shaped water pump, or even by nature.

Certain plants and seeds, like the maple and sycamore, have evolved similar shapes.

When they fall from trees, they look and work remarkably like helicopter blades.

At Joby, the design team is looking for the best shape to balance power and noise.

We went through a lot of experimentation with actual propeller, uh, prototypes.

We needed to put real work in, in terms of experiments, to really understand this phenomenon.

NARRATOR: To reduce noise, it helps to understand what causes it.

As each propeller blade slices through the air, it creates pressure vibrations.

The strength of those vibrations depends in turn on a propeller's shape, how fast it spins and the number of blades.

MIKIC: So we iterated with a number of designs.

We took blades with a lot of blade area and then much thinner blades and, uh, trying to see how that results in acoustic generation.

These propellers are turning much slower than traditional helicopter blades.

We varied the shape, a lot of experimentation.

I think this trial and error system is something that allows us to ever more refine design, produce and, uh, test, which, in multiple iterations, allows us to arrive to, uh, to optimal solutions.

NARRATOR: The company has tested several blade shapes, hoping to find the best combination of efficiency, lightness and durability.

To test each new propeller design, the company has built a large circular track in an old quarry near Santa Cruz.

MIKIC: In quarry, we have what we call "The Whirlybird," which is a track kind of like a roller coaster track that goes around in circles.

And we have to test this propeller not only in hover conditions, but through all the conditions that it experienced through transition as well as forward flight.

NARRATOR: On the track, they test each iteration of the propeller for durability and blade design, as well as for noise.

MIKIC: And then we adjust the angle of the propeller, the speed of the propeller, the variable pitch on it to see how it operates in different regimes of flight that the real airplane would experience.

And we can do this for hours on end, days on end, uh, to see how the system performs.

ARMANI: The design of a propeller is a very theoretically heavy lift.

However, at the end of the day, experimental results rule.

And their ability to build that huge test ring to really, you know, compare their experimental results with the, the theoretical predictions are really what allowed them to advance and push their entire plane forward.

NARRATOR: Ultimately, they discovered that their original design, which was wider, actually performed better than subsequent slimmer designs.

The greater surface area allowed them to slow down the propeller's rotation speed, reducing noise while meeting power requirements.

MIKIC: When you do the experiments, you realize you're going down the wrong path, then you start to go back and see, like, well, why is the thing that I tried to do that makes things better actually worse?

So you challenge your own assumptions.

DARAIO: Challenging assumption is something that is an essential component in engineering.

Being able to harvest the advances of divergent thinking and creative thinking is something that, in the end, promotes innovation and allows us to advance technology much faster.

NARRATOR: A change to the shape of the propeller helps with the nature of turbulence generated by the blade.

Exactly how they did it, a Joby representative said, is a trade secret.

But the result is a vehicle that the company says produces 100 times less acoustic power than a helicopter.

Eventually, they're hoping to expand their test program to include passengers and move toward full certification from the Federal Aviation Administration.

DIDIER PAPADOPOULOS: Safety is non-negotiable.

Look, I'm gonna put my kids on these airplanes, and so this is, this is close to me, just as it is close to everybody else.

WILSON: Now being able to travel routinely with an aircraft like this, and be able to do it relatively low cost and super available to the masses, is so exciting.

NARRATOR: Today, air travel accounts for an estimated 10% of the carbon produced by all transportation.

It's this kind of experimentation that could lead to bigger changes in air travel.

Electrifying aviation is one of the hardest engineering challenges we face.

But not every problem requires such a difficult solution.

When it comes to finding ways to reduce carbon emissions, there is some lower-hanging fruit.

Over thousands of years, we've gotten more and more efficient at growing food for an ever-growing population.

But the road from farm to table can be long and wasteful.

Globally, a third of all crops go bad before they reach the table.

And with food production accounting for about 30% of global greenhouse gas emissions, reducing food waste could be one solution to our climate problem.

At least, that's the idea behind a Norwegian rot-sniffing robot.

The BAMA food warehouse in Oslo, Norway.

NARRATOR: Anne Person is the director of quality assurance.

We get about 2,000 pallets in here every night.

NARRATOR: The produce comes in from 80 countries.

They're being scanned here.

And then they go straight to the quality control tower.

This is the first control that is being done when it comes to Norway.

NARRATOR: Inspectors screen the produce for spoilage, as best they can, before sending it to the supermarket.

The problem is we don't have very much time to inspect the pallets.

It's maximum 60 seconds.

And also, due to the setup of the quality stations, we are only able to control the two upper layers, maximum.

NARRATOR: That means, even with experience, visual inspection only goes so far.

Inevitably, some spoiled produce goes undetected and gets shipped along with the rest of the produce all over Norway to local supermarkets.

PERSON: So our question was, how can we check the whole pallets?

So that's when we started to look at the new technology.

The goal is increased freshness and reduced food waste.

If you can detect spoilage earlier in the value chain, we are also able to do more with the products that we might reject.

We can sort them, we can give them to food banks.

NARRATOR: BAMA connected with Tunable, a small tech company in Oslo, inventors of an artificial nose, or machine olfaction device, that is already in use monitoring the amount of greenhouse gasses emitted by container ships.

Tharindu Madduma is Tunable's business development manager.

MADDUMA: BAMA came to us.

They explained that they had this problem of determining the quality of the fruits and vegetables, being able to do it at a large scale and being accurate.

VALERO-CUEVAS: There's a long history of inventions that allow us to extend our senses.

So we've done that for sight.

We've done that for hearing.

MADDUMA: So, we have microscopes, we have hearing aid, but smell is still a sense that we haven't digitalized.

And that's what we're doing.

NARRATOR: Kristian Hovet is Tunable's C.E.O.

HOVET: When you take a breath, you're doing a multi-gas analysis.

You're pulling in molecules, and those molecules are detected by your nose, and then it's detected by your brain to tell you what you're smelling.

NARRATOR: The challenge for Tunable was to take their existing analyzer for emission analysis and increase its sensitivity without making the device too big and cumbersome to be useful on a warehouse floor.

So why use smell?

Our noses are sensitive detectors, able to identify a wide variety of chemicals in the air, even at low concentrations.

Airborne molecules can also potentially reveal what's hidden in the pallets.

These molecules tell a chemical story of fruits and vegetables as they rot.

But the device would have to be far more sensitive than a human nose, and able to detect spoilage more reliably than a human eye.

Produce, like all living things, decays after death as microbes consume dead cells, releasing volatile organic compounds.

In theory, the team should be able to tune their machine to recognize those molecules.

We knew that we could look at complex gasses.

We redesigned emission analyzer, and then we started testing.

NARRATOR: Eivind Jlke Rer is the lead engineer on the Tunable e-nose project.

RER: So now I'm going to measure fresh grapes and then some spoiled grapes.

See our e-nose can smell the difference.

I'll start with collecting a sample from the ambient air as a baseline for the measurement.

(machine whirring) And the noise you can hear now is actually the compressor pump pulling air, uh, into the analyzer.

So now I'm going to take a sample from the fresh grapes to see if there is anything present there.

NARRATOR: The probe pulls in air and then compresses it by a factor of five, which increases the density of the sample and makes molecules easier to detect.

Next, infrared light shines through the sample.

The light then passes through a chip that sorts different types of molecules based on the specific wavelengths of light they absorb, which ultimately allows the analyzer and accompanying software to reliably detect the presence and concentration of molecules that signal spoilage with extreme sensitivity.

RER: The reading I got now doesn't really show any molecules present at all compared to ambient air, which is more or less what I would expect from fresh fruit.

(machine whirring) So now I'm going to take a sample for the, um, spoiled grapes.

We see a clear difference.

We see up to 12% absorption at ethanol wavelength, which is a good indication that we actually smell the rotten grapes.

So, uh, this looks really promising.

HOVET: The fumes we were able to collect, we were able to see the, the kind of the signatures.

NARRATOR: The engineers then tested different kinds of fruits and vegetables as they decayed, building up a database of chemical profiles.

HOVET: We saw a tomato was different, somewhat, from a banana.

Grapes were different from avocado, for example.

And we thought, well, this must be interesting.

(laughs) (compressed air can sprays) NARRATOR: Thor Bakke is the founder and Chief Technology Officer of Tunable.

He's been working with microelectromechanical systems for over 30 years.

BAKKE: Tunable is a component, uh, inside our analyzers.

That's the Tunable filter.

It's used to change the wavelength of light so we can scan the wavelength and do spectroscopy.

(radio playing static between stations) Spectroscopy is very much like, uh, tuning a radio to find a particular station.

The gasses are separated in the infrared spectrum, just like radio stations.

And then you can basically detect each one of them.

So that's where the word Tunable comes from.

NARRATOR: After extensive fine tuning in the lab, it's time for the very first field test in the warehouse.

STELTZNER: Sometimes you can't learn about all of the variables that will be involved in an engineered system sitting on a desk with a pen and paper or at a computer screen.

You need to go out into the field.

You need to put it in the actual environment and see how it interacts, learn from that, make changes, and move forward.

RER: Now I'm capturing; I'm in there.

Now I'm ready to do the measurement on the grapes.

NARRATOR: Eivind watches the screen, waiting to see the telltale grape waveform.

But the pump just whirrs away.

And eventually he gives up.

Uh, I don't really know what happened here.

Uh... For some reason, um, the results wasn't as expected.

NARRATOR: The first time definitely wasn't the charm.

Murphy's law.

Yeah.

HOVET: We know that it works in a laboratory environment.

So the big thing now is showing that it actually works... (chuckling): ...in real life, and as you see, there's been some challenges.

CHACHRA: We tend to think of failure as a bad thing, right?

That something that is not supposed to happen, happens.

But if you're doing anything new, failure is an integral part of the process.

And the reason for that is because we can't perfectly predict or understand how things are gonna work in the real world until we try them.

NARRATOR: Turns out the warehouse temperature, a chilly 41 degrees Fahrenheit, affected the test result.

HOVET: The cold part.

We did know that it was cold in that area, but did we take it on account enough?

No, we didn't.

We should, of course, have thought about that.

But, uh, but that's the kind of the learning, that's the process.

NARRATOR: Back in the lab, the Tunable team recalibrated their chip to account for the BAMA warehouse temperature.

They also adjusted the design to include the pumps that compress the sample, increasing the density of the gas to compensate for the lower metabolic rate of the food in the refrigerated environment.

RER: It will be really interesting to see if the alterations we have, uh, made, will actually do the difference in the field.

NARRATOR: Eivind is back with the latest iteration of the e-nose.

Further testing in the lab showed that, even with the changes, the machine needs time to adjust to the conditions in the warehouse.

RER: Now, I'll let the instrument stay here for the night to reach a steady temperature, and then we'll do measurements tomorrow.

Well, after a long cold night, the system should be ready to go.

(machine whirring) Now we see absorption of light at more or less 9.5, ten microns, which, um, indicate ethanol being present.

This really shows that our new chip is working in this real environment.

NARRATOR: Eivind uses the e-nose to sample the air from various locations on the entire pallet stack.

RER: Actually, we see a spike at the ethanol absorption wavelength, so that might be something.

NARRATOR: They've taken an important step.

A successful real-world test of the newest version of the Tunable e-nose.

I'm not the most excited guy, but, um... (giggles) ...this is, uh, this is exciting.

(e-nose humming) I expected it, although you never know.

It's a big win.

I get very excited when technology works.

NARRATOR: Still, there is work ahead to make the technology viable and, most importantly, scalable.

MADUMMA: We hope that we can make them more efficient.

Food waste is enormous global problem.

8% of all greenhouse gasses comes from food waste.

So if we can be a part of the solution, it's huge.

NARRATOR: Reducing food waste is one of many ways engineers are trying to slow climate change.

But the negative changes we've made to our climate are already damaging some environments like coral reefs.

MOONEY: Coral reefs are in decline.

So one of the things that I really think about is how do we fix the environment that's sort of dying in front of us?

NARRATOR: Healthy coral reefs can be stunningly beautiful and play a critical role in coastal ecosystems.

They harbor a tremendous diversity of marine life and contribute to the overall health of the world's oceans and their coastlines.

A quarter of all marine species depend on them for survival.

They're also important to humans.

Often located in shallow water, they can protect coastal communities from damaging storm surges.

And the reefs host a primary, sustainable food source for hundreds of millions of people around the world.

But as the oceans warm, corals are struggling to survive.

Excessive heat drives away the microscopic algae the coral depend on.

That leads to a dramatic loss of color, known as coral bleaching-- a powerful visual indicator of an unhealthy reef.

But bleaching isn't the only indicator of a reef in peril... MOONEY: Not only it looks brown and is lacking these beautiful, vibrant colors, but it just sounds dead.

(underwater ambient noise) NARRATOR: That's where sensory biologist Aran Mooney comes in.

MOONEY: My background is in hearing and in bioacoustics.

And I study how animals perceive the world around them.

(wildlife chittering) Coral reefs are kind of rainforest of the sea, and just like a really rich forest might have a lot of birds calling, and you might hear the monkeys calling in the background, coral reefs are really the same.

So basically a healthy coral reef has a really healthy rich soundscape.

(crackling, snapping) NARRATOR: Snapping shrimp, lobster, and fish create a symphony indicative of a biodiverse community.

MOONEY: And a degraded coral reef is just an impoverished soundscape.

It sounds quiet, kind of desolate.

So, by listening to the soundscape, we can kind of track that biodiversity and understand when that change is happening.

NARRATOR: Off the coast of St. John in the Caribbean, a team from the Woods Hole Oceanographic Institution in Massachusetts conducts bleaching surveys, finding evidence of degraded reefs.

(water splashing) To your right, there's some bleached coral.

You knew there's going to be bleaching here, right?

But then it's freaking everywhere, right?

YOGI GIRDHAR: I've been coming here five or six years now, this was the first time I have seen such bleaching.

NARRATOR: Yogi Girdhar is a roboticist and computer scientist at Woods Hole.

GIRDHAR: I am working on robots and A.I.

and machine learning-based techniques to understand complex ecosystems in the ocean, such as coral reefs.

NARRATOR: A question they pose: is it possible to build a robot that can seek out and find healthy reefs on its own?

(electronic beeping) If they succeed, the robot could provide an efficient and cost-effective way to find healthy coral reefs, map them, and monitor their health.

(electronic crackling) The soundscapes recorded by the robot could be a vital tool in diagnosing reef health and tracking decline or improvement.

MOONEY: Good job, team!

NARRATOR: The team has been collecting data on reefs for over a decade.

You're going through this.

Yeah.

I might be able to thread it through here.

NARRATOR: They have mountains of information; including audio and video.

They've even created 3D models of the reefs for further study.

Helping them gather this data is this third-generation robot.

GIRDHAR: We call it CUREE-- C-U-R-E-E.

It stands for Curious Underwater Robot for Ecosystem Exploration.

NARRATOR: It's equipped with sensors, microphones, and cameras and is still very much under development.

GIRDHAR: The design of a robot is always evolving.

Our robot is never finished.

NARRATOR: It's an engineering challenge with a lot of moving parts.

So they've broken it down into many small steps.

MARIA YANG: There are many, many problems that you can solve with an engineering solution.

But I think you have to really understand what the problem is and sort of pick the two or three that really you want to address.

Otherwise, you kind of fall into this trap of trying to solve all the problems all at once and you run out of resources.

NARRATOR: This morning, the team is prepping for its latest test right off the dock.

MOONEY: All right, Dr. Girdhar.

Are you ready?

Always.

GIRDHAR: I'll manage the tether.

Got it?

NARRATOR: To start, they'll place a speaker on the ocean floor, playing a recording of a healthy coral reef.

A sound file they captured from a previous trip.

SETH McCAMMON: It should be on.

GIRDHAR: Yeah.

All right.

We hear it.

(electronic crackling) NARRATOR: They're hoping the robot will recognize the sound through the water and be able to record it.

In this outing, the robot is not moving autonomously.

Researcher Seth McCammon is operating the robot remotely to steer and position it for the test.

I'm getting it in line with the thing so we can start to look at the data.

GIRDHAR: If the robot doesn't work with this sound, it's probably not going to work on the real coral reef, so it's a good, good test.

NARRATOR: Experimenting with sound underwater is not a new idea.

In the 1800s, a Swiss physicist and a French mathematician, armed with a bell and stopwatch, measured the speed at which sound traveled underwater.

On one side of Lake Geneva, Charles Franois Sturm rang a submerged bell, (bell ringing) while Jean-Daniel Colladon used a long tube to listen underwater across the lake... (watch clicks) ...pressing his stopwatch to keep track of how long it took the sound to travel across.

Surprisingly, they found that water is a better conduit for sound than air.

Sound travels through water roughly five times faster.

Today, the Woods Hole team will be using the speed of sound underwater as part of their calculations.

The robot is equipped with four microphones designed for underwater use called hydrophones.

As the sound from the speaker speeds through the water in all directions, it reaches the hydrophones at slightly different times-- just milliseconds apart.

The researchers look at a computer display that shows the signals recorded... (electronic chirping) ...on each hydrophone.

McCAMMON: And so it will hit one hydrophone before the others and by looking at the relative time of arrival at those different hydrophones, we can figure out which direction it came from first and then steer the robot in that direction.

NARRATOR: The robot correctly identifies the direction of the sound-- an important first step toward autonomous navigation.

A small but important victory.

McCAMMON: It's like you're building out of LEGOS and you're building up a house, brick by brick by brick.

And it only works when the house is fully done.

But you need to know that each single brick in that works on its own in isolation before you're willing to add it to the larger picture.

MABRY: And so, you have this massive goal that you're trying to achieve, but there needs to be attainable goals along the way because ultimately, you're dealing with a system of components, a system of elements that need to work together in order for this to be successful.

NARRATOR: CUREE is ready to step up to a bigger challenge.

Locating an actual healthy reef by sound-- something less predictable than what the speaker provided.

One of the healthier reefs in St. John is in nearby Joel's Shoal.

GIRDHAR: I propose we drop the robot like 20 meters... MOONEY: We're like ten meters off the reef right now.

NARRATOR: They'll place CUREE approximately 20 meters from the reef.

(electronic chirping) To succeed, it just needs to orient itself toward the sound.

Robot going in.

All right, cast away!

(electronic melody) McCAMMON: So the test today is mostly just trying to figure out if the robot can accurately determine which direction the reef sound is in.

NARRATOR: It's a more complex test.

This time CUREE is untethered and the boat is drifting with the ocean current.

NARRATOR: If they lose contact, they could easily lose the robot entirely, and all of the engineering that went into it.

MABRY: When they began to design this autonomous robot that would go underwater, there is a need to make sure that this thing is able to behave in an environment where, if it doesn't, we can retrieve it... NARRATOR: CUREE locates the direction of the healthy reef.

Which is encouraging.

NARRATOR: It's another successful test.

(electronic crackling) The next big hurdle, can CUREE not only locate, but then move towards a healthy reef autonomously.

This will be a crucial milestone in the mission, which is to ultimately build a fleet of robots to map, monitor, and record the health of corals around the globe.

While reefs are under serious threat all over, there are some signs of hope, and some surprising ideas for ways to protect them; including one that came from this team's research.

In their work, they discovered that the sound of a healthy reef might actually have an indirect healing effect on a stressed reef.

It has to do with the coral animal's life cycle.

Newly born baby corals-- tiny larvae-- drift in the ocean, searching for somewhere to settle.

It turns out the sound of a thriving coral reef signals them to settle into place.

Once they find a spot, they can be very resilient and grow for centuries.

So the more larvae a reef can attract, the healthier it will be.

And that gave the team an idea.

We know these reefs are degraded and we want to rebuild them by attracting the larvae, the baby coral.

NARRATOR: In a past experiment, the team found that larvae could be drawn to recordings of healthy reefs.

So by placing speakers in strategic locations, they could give a boost where it's needed most.

MOONEY: And that system actually leverages the healthy landscape and plays it back into the environment and the idea is that it induces coral larvae to kind of choose that environment and settle.

NARRATOR: The result?

Up to seven times more larvae settlement compared to a degraded reef without the audio boost.

A very encouraging sign.

But back to St. John and CUREE.

The team is ready for the final test of the day.

McCAMMON: The robot is going to use the direction that it's finding from its hydrophones and then drive itself to whatever the nearest acoustic source is, which we're hoping is going to be Joel's Shoal Reef.

NARRATOR: This time, since CUREE will pilot itself, it's tethered for safety.

They put CUREE in the water and give it the green light.

NATE FORMEL: Are we expecting it to be moving or not?

McCAMMON: We are.

NARRATOR: It looks at first as though it's orienting toward the sound of the reef.

It thinks it's moving.

NARRATOR: But after a few minutes it's clear that CUREE isn't making much headway.

It's just dumb stuff in the way that I wrote.

NARRATOR: It seems there's an issue with the software.

All right, bring it back.

(ratcheting) It's coming up.

FORMEL: I can now see it.

NARRATOR: They're starting to lose the light.

It's getting dark.

(indistinct chatter) NARRATOR: They weren't able to check off everything on the day's to-do list, yet they remain upbeat.

GIRDHAR: Overall, I am happy right now because... McCAMMON: We ended the day with as many robots as we started the day with.

NARRATOR: It's frustrating in the moment, but they're making progress.

STELTZNER: The creative act of engineering has got disappointment, has got failure, and that's how we learn.

(chuckling): So, it is a big ball of, of... ...two steps forward and one step back.

When you have a very massive "Why" and a very massive purpose for what you're trying to do, such as save the coral reefs, it allows you to experience the disappointment but not be defeated by it, and continue to try the process of moving it forward.

If you're not failing you're not trying hard enough.

(voiceover): Yeah, it's very frustrating but when it works, it's very satisfying.

NARRATOR: Engineering solutions to the climate crisis will require creativity, innovation, and a global commitment to making smart choices.

But we face many other challenges as well; like restoring balance to the land after decades of industrial pollution.

On Navajo land in Arizona, an Indigenous artist and engineers are collaborating on a unique, local approach to purifying contaminated drinking water.

(birds chirping) This pristine-seeming landscape conceals a serious problem.

30% of the population in the Navajo Nation lacks access to clean drinking water.

Decades of uranium mining has polluted the land.

The United States government used the heavy metal to develop the atomic bomb and power its nuclear weapons program after World War II.

CHACHRA: When we think of engineering, people are suspicious of it because, for a good part of the 20th century, one of the stories of engineering was engineers making decisions about systems that affected a lot of other people.

And often those effects were not positive.

NARRATOR: Byproducts of uranium mining, such as strontium, can mimic calcium in the body, causing it to be absorbed by bones.

The E.P.A.

has awarded $3.8 million to support three drinking water projects to benefit the Navajo Nation.

Some are proposing other, more homegrown solutions, as well.

(stone grinding) Deanna Tso is a third-generation Navajo artist who works in clay.

TSO: People always ask me, "When'd you learn how to do pottery?"

I always say, "I was born making it."

Both my parents, my mother and my father, both did Navajo pottery.

(car doors closing) NARRATOR: She has been collaborating with scientists Navid Saleh and Stetson Rowles... (knocks on door) Hey!

Good morning.

Hey, Deanna.

NARRATOR: ...on a project meant to address the water contamination problem on a very human scale.

SALEH (voiceover): I believe that engineering without people is destined to fail.

Good.

Good.

Long drive.

SALEH (voiceover): There is this experiential knowledge, knowledge that is housed within people's lives, yet to be unlocked.

NARRATOR: Not all people here use or have access to municipal water, so the goal is to call upon local knowledge to find a sustainable way to purify water closer to the home.

YANG: We often think of engineering as only being the latest and greatest technology.

But, people have practices that are very effective now and, and have been for, you know, decades, centuries longer.

And so what can we learn from those, existing approaches that are already effective?

So Deanna, this was something that... NARRATOR: On this trip, the scientists want to build a new prototype clay filter for use in household water containers.

The hope is to integrate locally sourced minerals so that the finished filter will remove uranium byproducts, like strontium, from the water.

SALEH: Could you actually make something like that?

Do you have something similar?

I have one that I make with the cone shape.

NARRATOR: Navajo potters like Deanna use a local tree sap as a glaze.

Navid and his team wondered if the sap could be used as part of a decontamination filter.

SALEH (voiceover): What we found was how much knowledge the Navajos already had about the sap.

They already knew it has health benefits.

So this is a printout of the... NARRATOR: Navid and his team recently conducted tests that translated Indigenous knowledge into the language of biochemistry; quantifying the extent of the sap's antimicrobial properties.

Now, they hope to expand the filter's capabilities to radioactive contaminants.

YANG: They worked together, collaboratively, to make something new and better that serves her community in a really, powerful and very collaborative way.

We can engineer a shape or a design that's going to work well, not only to filter water, but people will want to use.

(voiceover): We see this amazing opportunity to be able to use pottery, or ceramics, as filters, because it's so a part of people's everyday life.

Particularly in places like the Navajo Nation where traditional practices are so important.

TSO: Okay.

ROWLES: Which way?

NARRATOR: Navid and Stetson want to learn the process of making pottery the way Deanna's mother taught her-- because collaboration is strongest when it is truly interdisciplinary.

TSO: Yes.

You see that gray spot?

NARRATOR: Deanna starts from scratch, harvesting clay from a rocky outcropping on Navajo land.

Okay, so this portion is what?

That portion is clay.

Okay.

SALEH (voiceover): We often as scientists believe that we know a lot.

But we forget, science as a discipline has only been around for 500 years.

NARRATOR: There are many ways of generating knowledge besides the modern scientific process.

CHACHA: These are all different ways in which we interact with the physical world.

That diversity gives you new ideas.

And thinking about how to put together old technologies and new technologies might lead to entirely new paths.

It creates a symbiotic effect, because the more people feel included in what is being produced by something, the more people see themselves being a part of the producing of that thing.

NARRATOR: Next-- they source sap from pinyon trees.

There's one right here, let's check this one.

(crunches) ROWLES: Whoo!

We hit the jackpot with this tree.

TSO: We were blessed for the day.

Come on in.

(keys jangling) I usually just take this much out.

NARRATOR: Deanna demonstrates how to grind minerals into the fine grains that make up her clay.

One of you want to go ahead and give it a try?

ROWLES: I think there's a lot of engineering that goes into creating pottery.

The freedom that it allows to make any shape.

(squeaking) STELTZNER: The fusion of art and engineering.

Or maybe even the boundaries between art and engineering... ...perhaps they don't exist.

Perhaps they're really the same thing, painted with a different palette.

NARRATOR: Stetson and Navid are working with Deanna to prototype a shape for the clay filter.

I don't know if you know Deanna, but I've been making some pottery since high school, and I made this shape to try and see if maybe we can explore making some shapes together.

I made a shape similar to that... ...and it looks like this.

And we do make these traditional Navajo pipes.

Do you think you can make some grooves similar to something like this?

Kind of like an accordion basically, so it has the same surface area but in a smaller size.

NARRATOR: Adding grooves increases the total surface area of the shape.

More surface area will mean more contact with the water inside.

TSO: I'm going to show you an option we have that we can try: Coil.

Yeah.

Making a coil.

Making a coil.

NARRATOR: Next, the new prototypes need to be fired.

SALEH: We have been working with Deanna for almost nine years now.

TSO: Make sure we have it covered nice and good.

SALEH: Working with her side-by-side as an equal partner intellectually, only opens opportunities that are more meaningful than we scientists would ever find sitting at our desks.

NARRATOR: The last step: heat and strain the pinyon sap, creating the microbe-resistant resin, which acts as a glaze to coat the pottery.

And now, a new addition to the filter.

ROWLES: Can you grab the zeolite?

NARRATOR: The scientists are using powdered chabazite, a type of naturally occurring zeolite, found abundantly on Navajo land.

Chabazite is a porous crystal made of sodium, calcium, and aluminum silicates that has the ability to trap and absorb contaminants.

Finally, Deanna applies the resin.

TSO: The pottery itself has to be hot.

The sap has to be hot.

NARRATOR: The team hopes the chabazite will add function to the resin, removing uranium byproducts, like strontium, from any water that comes into contact with it.

ROWLES: Wow, the colors are beautiful.

NARRATOR: Back at the University of Texas at Austin, it's time to test their water filter prototypes in the lab.

We've got some of the clay.

NARRATOR: Using the materials they sourced with Deanna, the scientists create small clay discs... ROWLES: ...try and just punch out, a little disc like that... NARRATOR: And coat them with the same chabazite-enriched resin.

These are tiny lab versions of Deanna's pottery.

To test the discs, the researchers expose them to strontium-contaminated water to see if the resin will successfully absorb the uranium byproduct.

If the filter works as expected, the chabazite will capture strontium from the water through ion exchange as the water passes through.

ROWLES: Hey, Andrei.

ANDREI DOLOCAN: What's up, bud?

Here's the sample.

Yeah, thank you.

NARRATOR: Senior research scientist Andrei Dolocan loads a sample into an ion mass spectrometer.

It scans the sample on the molecular level, layer by layer, over several hours.

When it's done, the result is a map of the elements within the scanned sample surface.

When the clay disc is completely scanned, it's time to check the results.

This is the strontium signal.

NARRATOR: The data show that the strontium is found in the same places as chabazite in the resin... DOLOCAN: We have the zeolite, obviously sodium, aluminum-silicon.

Uh-huh.

DOLOCAN: Okay.

And now the, strontium is increasing exactly like... NARRATOR: It's an encouraging sign that the chabazite is working as expected when used with Deanna's pottery technique.

SALEH: So I guess it was a really, successful run, Andrei.

Yeah.

We can see association of strontium with the zeolite.

DOLOCAN: I agree, this is a good start.

ZILEVU: One thing that I've learned from the research and design process is that kind of doing co-creation activities with the end user, it's really a way to kind of bridge and create new, innovative process, because you're bringing the people who are using the technology throughout the whole journey.

So this is the one that Deanna made... NARRATOR: Now a few steps closer to their goal, the researchers will work to incorporate Deanna's spiral and the chabazite's filtering power into their final design.

So moving forward, I think the most difficult engineering challenge is yet to come.

And I think it's going to be translating our results from, you know, a lab scale experiment to something that's going to be usable in households throughout the Navajo Nation.

(birds chirping) MABRY: At the end of the day, we want to unlock human potential.

And in order to unlock human potential, we are not doing ourselves a justice if we continue to only demand certain solutions from a subset of our populations, the more we can get more people included, the more we can unlock not just solutions to problems that we now see, but things that are yet to come.

NARRATOR: As we change our world through engineering, it's up to us to make changes; for all of us, by all of us.

ARMANI: I think we're all engineers.

We all build things, we all design things.

(chuckling): We all break things and then have to fix them and put them back together.

NARRATOR: And we get to decide what comes next.

What if we were to design this?

What if the world was to look like this in 50, 100 years?

What could that look like?

ALI HAJIMIRI: The engineer's work is never done...

If you're not failing, you're not trying hard enough.

You can always create something new.

NARRATOR: Building stuff to change the world.