Narrator: Our oceans connect us
A vast network of waterways supporting the global transit of
almost 80 percent of all goods.
That's nearly 11 billion tons of food, medicine, and many items
we rely on in our daily lives.
With coastlines constantly changing,
how do large ships safely navigate these waterways?
With shallow water features such as reefs and shoals,
it is essential to have accurate maps
so ships can avoid these serious navigation hazards.
In the summer of 1975, Jacques Cousteau and NASA
teamed up with Landsat satellites to see if the same technology
that discovered new coral reefs, corrected coastline maps,
and revealed uncharted islands
could also measure shallow water depth from space.
Bernard: By the radio, we get the information of Calypso that said,
"Go, now!"
Narrator: Measurements of water depth or bathymetry
allow scientists to chart the marine landscape.
And just as aerial photography revolutionized topographic mapping,
scientists had a hunch that satellite observations
could do the same for bathymetry.
The 1970s ushered in a new era of global maritime trade
and an unprecedented demand for crude oil.
resulting in the design of ultra-large crude carriers or supertankers
capable of carrying up to 30 times more oil than previous tankers.
Just one of these massive ships could cause a catastrophic
environmental disaster, spilling millions of gallons of crude oil
if they ran aground.
A leading voice of marine environmentalism at the time
was Jacques Cousteau, the world's most famous aquanaut.
He expanded the growing conservation awareness
from the land to the seas
and set the groundwork for the ocean environmental movement.
The newly launched Landsat satellites
provided a new vantage point from above
and opened up a world of possibilities
for ocean monitoring from space.
Through George Low, the Deputy Administrator of NASA,
Cousteau connected with Russel Schweikart,
a former Apollo 9, Skylab astronaut.
Together, the aquanaut and the astronaut embarked on a
three-week long expedition to find out whether Landsat satellites
could make accurate bathymetry measurements.
A team was assembled: Cousteau and his experienced divers,
Rusty Schweickart, a jet-flying, scuba-diving astronaut,
NASA and university scientists,
and the president's son, Jack Ford, an experienced scuba diver.
But they still needed a radio operator
to coordinate the experiment's satellite based communications.
David Lychenheim, a 23-year-old engineering student
overhead a NASA scientist talking about the position.
David: And I raised my hand and I said, "I'll leave tomorrow."
I was first to go to Goddard Space Flight Center
and get some training on the gear that was on the Calypso
as a radio slash communications engineer.
The Calypso was a 1942 wooden minesweeper,
very narrow and maximum speed was ten knots.
It was very slow, but the ship did what it supposed to do.
It was equipped with a mobile laboratory for underwater research
and also had a lot of satellite gear for communications.
So I had some training for a week or two, figuring out orbits
and locations of satellites
and then I was off to Montego Bay, Jamaica.
Narrator: David met Cousteau and his team as they prepared
the Calypso to set sail for the Bahama Islands.
There, the clear waters of the Western Atlantic
provided the perfect test site for measuring water depth from space.
David: Eventually, we moved to the Bahama area
to do this Landsat coordinated effort with another research vessel
called the Beayondan.
Beautiful sailboat actually,
it was outfitted for scientific experiments such as
water salinity tests and whatnot.
So they followed the Calypso around pretty much all of the Bahamas,
where we were coordinating with Landsat.
Beayondan, Calypso, the divers,
all this was a part of this coordinated plan.
My role on a daily basis was morning and afternoon
I would give the captain a Polaroid that had a picture of the local area
showing any weather patterns that might have cropped up.
In addition to that, my job was to ensure good communications
between the Zodiacs that the divers were on, the Beayondan,
also Rusty Schweickart who flew the NASA T38 jet at high altitude,
and I would coordinate with the Landsat Group
via Goddard Space Flight Center.
All those things had to be coordinated closely for timing and location.
Narrator: Once in position, the Calypso and Beayondan recorded
the water’s depth using their sonar.
Then, as a Landsat satellite passed overhead, the ships and
diving teams made a series of precisely timed measurements.
As Cousteau’s chief diver for the expedition,
Bernard Delemotte recalls:
Bernard: By the radio we get the information of Calypso that said,
say, "Go, now!"
Narrator: That was the signal for the Zodiac divers to start
making their measurements.
Bernard (in French): At this instant, we had to take three different
precise measurements:
the temperature, the vertical visibility,
the horizontal visibility,
and when the depth did not exceed 20 meters
we took a sample from the bottom (of the ocean).
Narrator: Each night, the boats sailed 90 nautical miles westward
to the next experiment site.
And were ready to take new measurements
when Landsat passed overhead in the morning.
David: After deciding where we would position the ships,
we would move throughout the area.
We were in Nassau, we were in Eleuthera, Northwest Channel
Bimini, Barry Islands. We would hopscotch back and forth.
Narrator: With the detailed measurements taken by Cousteau and
his team, NASA scientists demonstrated that in similar conditions
depths of up to 72 feet could be measured by Landsat.
Those early satellite-derived bathymetry measurements
revealed previously unknown shoals, uncharted reefs, and
other navigational hazards.
And also helped revise charts of clear water coastal areas,
making sailing safer around the world.
This work gave birth to the field of satellite-derived bathymetry,
and the field continues to evolve today
with missions like ICESat-2.
The experiment also had a profound impact on David.
David: This expedition changed my life.
I returned to Maryland and then got a job
at Goddard Space Flight Center.
And I worked there for the next 30 years.
Narrator: Since 1972, Landsat satellites have been steadfast
observers of our changing planet,
making more and better observations with each new satellite.
Landsat 9, the newest satellite in the series,
will continue recording the spectral story of
Earth's ever changing land surfaces and coastal waters.