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Narrator: Our oceans connect us

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A vast network of waterways supporting the global transit of

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almost 80 percent of all goods.

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That's nearly 11 billion tons of food, medicine, and many items

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we rely on in our daily lives.

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With coastlines constantly changing,

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how do large ships safely navigate these waterways?

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With shallow water features such as reefs and shoals,

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it is essential to have accurate maps

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so ships can avoid these serious navigation hazards.

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In the summer of 1975, Jacques Cousteau and NASA

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teamed up with Landsat satellites to see if the same technology

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that discovered new coral reefs, corrected coastline maps,

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and revealed uncharted islands

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could also measure shallow water depth from space.

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Bernard: By the radio, we get the information of Calypso that said,

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"Go, now!"

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Narrator: Measurements of water depth or bathymetry

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allow scientists to chart the marine landscape.

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And just as aerial photography revolutionized topographic mapping,

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scientists had a hunch that satellite observations

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could do the same for bathymetry.

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The 1970s ushered in a new era of global maritime trade

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and an unprecedented demand for crude oil.

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resulting in the design of ultra-large crude carriers or supertankers

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capable of carrying up to 30 times more oil than previous tankers.

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Just one of these massive ships could cause a catastrophic

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environmental disaster, spilling millions of gallons of crude oil

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if they ran aground.

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A leading voice of marine environmentalism at the time

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was Jacques Cousteau, the world's most famous aquanaut.

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He expanded the growing conservation awareness

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from the land to the seas

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and set the groundwork for the ocean environmental movement.

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The newly launched Landsat satellites

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provided a new vantage point from above

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and opened up a world of possibilities

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for ocean monitoring from space.

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Through George Low, the Deputy Administrator of NASA,

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Cousteau connected with Russel Schweikart,

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a former Apollo 9, Skylab astronaut.

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Together, the aquanaut and the astronaut embarked on a

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three-week long expedition to find out whether Landsat satellites

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could make accurate bathymetry measurements.

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A team was assembled: Cousteau and his experienced divers,

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Rusty Schweikart, a jet-flying, scuba-diving astronaut,

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NASA and university scientists,

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and the president's son, Jack Ford, an experienced scuba diver.

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But they still needed a radio operator

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to coordinate the experiment's satellite based communications.

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David Lychenheim, a 23-year-old engineering student

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overhead a NASA scientist talking about the position.

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David: And I raised my hand and I said, "I'll leave tomorrow."

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I was first to go to Goddard Space Flight Center

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and get some training on the gear that was on the Calypso

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as a radio slash communications engineer.

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The Calypso was a 1942 wooden minesweeper,

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very narrow and maximum speed was ten knots.

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It was very slow, but the ship did what it supposed to do.

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It was equipped with a mobile laboratory for underwater research

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and also had a lot of satellite gear for communications.

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So I had some training for a week or two, figuring out orbits

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and locations of satellites

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and then I was off to Montego Bay, Jamaica.

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Narrator: David met Cousteau and his team as they prepared

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the Calypso to set sail for the Bahama Islands.

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There, the clear waters of the Western Atlantic

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provided the perfect test site for measuring water depth from space.

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David: Eventually, we moved to the Bahama area

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to do this Landsat coordinated effort with another research vessel

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called the Beayondan.

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Beautiful sailboat actually,

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it was outfitted for scientific experiments such as

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water salinity tests and whatnot.

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So they followed the Calypso around pretty much all of the Bahamas,

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where we were coordinating with Landsat.

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Beayondan, Calypso, the divers,

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all this was a part of this coordinated plan.

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My role on a daily basis was morning and afternoon

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I would give the captain a Polaroid that had a picture of the local area

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showing any weather patterns that might have cropped up.

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In addition to that, my job was to ensure good communications

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between the Zodiacs that the divers were on, the Beayondan,

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also Rusty Schweikart who flew the NASA T38 jet at high altitude,

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and I would coordinate with the Landsat Group

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via Goddard Space Flight Center.

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All those things had to be coordinated closely for timing and location.

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Narrator: Once in position, the Calypso and Beayondan recorded

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the water’s depth using their sonar.

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Then, as a Landsat satellite passed overhead, the ships and

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diving teams made a series of precisely timed measurements.

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As Cousteau’s chief diver for the expedition,

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Bernard Delemotte recalls:

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Bernard: By the radio we get the information of Calypso that said,

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say, "Go, now!"

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Narrator: That was the signal for the Zodiac divers to start

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making their measurements.

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Bernard (in French): At this instant, we had to take three different

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precise measurements:

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the temperature, the vertical visibility,

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the horizontal visibility,

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and when the depth did not exceed 20 meters

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we took a sample from the bottom (of the ocean).

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Narrator: Each night, the boats sailed 90 nautical miles westward

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to the next experiment site.

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And were ready to take new measurements

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when Landsat passed overhead in the morning.

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David: After deciding where we would position the ships,

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we would move throughout the area.

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We were in Nassau, we were in Eleuthera, Northwest Channel

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Bimini, Barry Islands. We would hopscotch back and forth.

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Narrator: With the detailed measurements taken by Cousteau and

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his team, NASA scientists demonstrated that in similar conditions

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depths of up to 72 feet could be measured by Landsat.

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Those early satellite-derived bathymetry measurements

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revealed previously unknown shoals, uncharted reefs, and

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other navigational hazards.

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And also helped revise charts of clear water coastal areas,

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making sailing safer around the world.

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This work gave birth to the field of satellite-derived bathymetry,

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and the field continues to evolve today

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with missions like ICESat-2.

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The experiment also had a profound impact on David.

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David: This expedition changed my life.

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I returned to Maryland and then got a job

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at Goddard Space Flight Center.

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And I worked there for the next 30 years.

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Narrator: Since 1972, Landsat satellites have been steadfast

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observers of our changing planet,

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making more and better observations with each new satellite.

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Landsat 9, the newest satellite in the series,

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will continue recording the spectral story of

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Earth's ever changing land surfaces and coastal waters.