DAISY: NASA engineers have designed and built some amazing
telescopes, satellites, and space probes, looking out to
the far regions of the Milky Way and the universe...
But some of the most important things they monitor are right
here. Looking back at us from space, NASA's Earth Observing
System is helping to preserve our world's natural resources.
Find out how, next on Real World.
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DAISY: NASA's Earth Observing System plays an important role
in the recovery efforts of a vital ecosystem,
the Chesapeake Bay. The Chesapeake is an estuary,
a partially enclosed body of water where freshwater mixes
with the salt water of the sea. The Chesapeake Bay is the
largest estuary in the US, stretching more than 300
kilometers from the top of Maryland to the Atlantic Ocean
in Virginia.
It holds about 57 trillion liters of water and is the home
of more than 3600 species of wildlife.
But human impact has changed the Bay and it isn't as healthy
as it once was. To better understand those changes,
bay managers monitor the Chesapeake...
and that's where NASA helps.
The agency is using satellites, like LandSat, MODIS and SeaWifs
to keep an eye on the bay, collecting data that scientists
use to monitor its conditions.
Scientists analyze the data to understand the changes and
predict what might happen in the future.
ERIC BROWN DE COLSTOUN: We monitor satellite data over
time to see how things are changing
DAISY: Eric Brown de Colstoun is an associate Research
Scientist with the University of Maryland, Baltimore County.
He works at NASA's Goddard Space Flight Center.
ERIC: We have to develop a big mosaic of the Chesapeake Bay
Watershed from LandSat, so we take 22 different images that
we have to stitch them together, if you will...
and that's kind of the base data.
DAISY: Four centuries of population growth have crippled
the bay, harming water quality and threatening the species
that rely on clean water for survival. About half of the
water in the Chesapeake Bay comes from the Atlantic Ocean.
The other half drains into the Bay from its enormous
watershed, a 165 thousand square kilometer
area that covers parts of six states.
ERIC: This image was put together by hundreds of
different images of LandSat. We're trying to put together a
mosaic of this whole region, over time.
DAISY: Most of the pollutants in the bay come from the
watershed. The watershed acts like a huge funnel, collecting
water from rain or snow melt. Some of the water soaks into
the ground; some becomes runoff that collects contaminants as
it drains downhill into the waterways that feed the bay.
Watershed runoff carries pollutants from farms, suburban
lawns and wastewater treatment plants, into 5 major rivers,
and eventually into the bay itself.
Eric studies the land cover in this region.
Land cover is the physical material at the surface of the
earth. Land cover like marsh and forest is good for the bay.
It acts as a filter, holding the pollutants away from the
water. Land cover like pavement creates problems.
The built up surface can increase the strength of runoff
into the streams, as well as add pollutants.
Polluted run off, from the Chesapeake Bay's watershed
causes Eutrophication.
JACKIE HARMON: Eutrophication is a process that ultimately
diminishes oxygen levels in the water.
DAISY: Jackie Harmon is a Virginia Oyster Restoration
Specialist for the Chesapeake Bay Foundation.
JACKIE: What happens is, we have excessive algae blooms
that are generally fueled by nitrogen that comes into the
bay. Nitrogen, a lot of times, is used as a fertilizer on the
land, and it does the same thing in the water that it does
on the land. It makes plants grow, and the specific plant
that it really fuels growth for in the bay is algae.
DAISY: So the algae consume the nitrogen, grow, and eventually
die. The decomposition process consumes oxygen in the water.
JACKIE: That's a major issue because the oxygen that the
bacteria in the decomposition process are using is the same
oxygen that the fish and the crabs and the oysters
need to live. DAISY: Water with a low
concentration of dissolved oxygen is called hypoxic.
And hypoxic water is not a good environment for wildlife.
JACKIE: So it makes it very difficult for other animals to
survive in areas where there's low oxygen, and ultimately it
becomes referred to as a dead zone.
DAISY: And the delicate ecosystem of the bay is
changed. But with images from NASA satellites, scientists and
policy makers can identify land cover and changes in land cover
that contribute to runoff into the bay.
NASA, along with the US Geological Survey,
manages the LandSat satellite. LandSat records pixels;
small pieces of the earth's surface just 30 meters by 30
meters, when put together, give an overall view of the bay.
Scientists locate individual pixels based on coordinates and
latitude/longitude. Images can be put together in a grid or
coordinate system like you might find on a road map.
Scientists can compare the same pixels over time,
to measure changes in that particular area.
ERIC: There's another example for Washington D.C. So you see
Rock Creek Park, Greenbelt Park. You see the Mall,
I guess Hains Point, Andrews Air Force Base.
So you can actually see the runways. And so what they've
done is, they've actually tracked this over time.
And see where things, where the urbanization has gone, as well.
DAISY: This and other information from NASA
satellites help Chesapeake Bay managers enact policies in very
geographically specific locations, to reduce toxic
pollution, and improve water quality.
Both Maryland and Virginia use data collected by LandSat to
prioritize land conservation actions.
And the effect....
Well, there's a long way to go. The Chesapeake Bay Foundation
has been measuring the health of the bay since 1998.
Each year, officials grade the bay on a 100 point scale.
A score of 100 would equal the pristine state of the
Chesapeake, as Captain John Smith explored it upon arriving
in the new world in the 1600s.
The numbers correlate to a letter grade, and while the
scale's a little different, it's not unlike the grade you
might receive on a math or science test.
For the last few years, the bay received a 28 - a D.
JACKIE: Overall, the bay is pretty sick. It's, it's not,
it's not saved. We... We know how to do it.
It's going to take a lot of action on the land as well as
things done in the water, like active restoration,
but, we still have a ways to go.
DAISY: The foundation has set a goal of reducing the amount of
nitrogen pollution entering the bay, by more than half,
to 50 million kilograms per year. That would be a huge
step towards getting the bay removed from the nation's dirty
water list.
So while the path to a healthier, more productive
Chesapeake bay is still long,
NASA and its partners, through satellite missions like LandSat
and Sea Wif are helping to make that journey possible.
JACKIE: Listen all you all, what I'm about to say.
It's time to get together to save this bay. With a creature
that's been around for thousands of millennia. It
goes by the name of Crassostrea Virginica. Some people eat
Ďem. The bay really need Ďem. They're chillin' under water
cause they're filter feedin'. There are so many cool things
oysters do. There reefs are habitat for an underwater zoo.
With gobies , linis, oyster-toed fish, crabs and eels and
worms and shrimp. You say you have a hard time believin'
this? You can trust me. I'm a specialist. Go and spread this
message all across the nation, about a funky new science
called oyster restoration.
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