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LOVERS - Land and Ocean Views of Earth by Remote Sensing (Grades 4-7)

Master Teacher

Lemuel Patterson

Background

There are several Landsat satellites. Landsat satellites are polar orbiting satellites. They are only 800_900 kilometers in space from Earth. Landsat satellites photograph the Earth using different wavelengths of reflected light from the sun. Some satellite sensors like the Multispectral Scanner (MSS) record data in infrared and visible bands. The later models of Landsat satellites use Thematic Mapper^TM. The satellite records reflected sunlight from objects in six bands and one thermal band. The six bands include blue, green, and red visible wavelengths of light and three infrared waves. The thermal band measures heat given off from land objects.

Overview

After viewing the video, students will be able to explain how satellites help scientists to see more than with the unaided eye and how Landsat technology works. Students will be able to identify vegetation and fire sites in the rainforest and detect erosion along rivers. Students will be able to use Landsat data to analyze other questions posed to them.

SC Math/Science Standards Met

Science Achievement Standards

Area IV—Applications
Strand 2: A, B
Process Skills: A, B, D, E, F, and G
National Science Education Standards

Grades 5_8
Content Standard E

Learning Objectives

Students will be able to use satellite images to:

identify geological features such as lakes, rivers, mountains, hills, and plains
analyze images of rivers for sediment flows
identify vegetation
compare/contrast varying vegetation images
create a map

Materials

Per person:

hand lens
map
pencil
crayons (4 different colors per person)

Vocabulary

(See glossary at end of lesson.)

analog
altitude
binary
digital image
grayscale
ground-truthing
image
INSAT
Landsat
pixel
remote sensing
resolution
SPOT
swatch
Thematic Mapper^TM

ITV Series

What's in the News: Space, Lesson #10, "Landsat Satellites"

Previewing Activity

Ask students to select a country they are inter-ested in investigating and to create a map of it. Students may use any physical map as a reference to trace and for color data. Assign colors: black (water), red (trees), blue (cities), and brown (barren soil). Have students present their landscape maps to the class members.

Focus for Viewing

Tell students that the purpose of Landsat satel-lites is to take images of the Earth. Depending on the requested pictures, there must be visible light and good weather. Ask students to brain-storm a list of things that they believe to be visible features of the Earth from space. Then have them look for those features in the video.

Viewing Activities

Start the video at its beginning. Pause at the black, red, and white image, and when the narrator says, "Computers on Earth are pro-grammed to take numbers from the satellite and convert them into pictures." Ask students if any of the composite pixel images are recognizable in the picture? Why or Why not? (The image is an analog image of pixels.)

Resume the video as the narrator says, "Scientists and engineers can then use those pic-

tures to study our environment and identify changes.…" The TV monitor shows a scientist seated in front of several monitors digitizing images from a Landsat satellite.
Tell students they are looking at a Brazilian rainforest. Stop the video when the narrator says, "Here is a Brazilian rainforest." Ask students what is in the image in red. (Vegetation.)

Ask them why there are patterns of white lines in horizontal rows. (Fire roads.)

Resume the video when you see the printed date "1975 Brazilian Rainforest" and the narrator says, "Here are two images of the Brazilian rainforest." Pause when the narrator says, "Here are two more Landsat photographs. They are of identical places on the Omo River in East Africa." Tell students they are looking at the Omo River in Ethiopia. Ask them to name several farming practices that may cause more sediment than average to build up in a river. Have students explain how this occurs.

Resume several frames very slowly in the video. When you see the characters "Mississippi River Delta 1973" and hear the narrator say, "The sediment is represented in aqua blue," pause. Tell students they are looking at the Mississippi River Delta. Ask them what could cause the delta to expand. (Accept all reasonable answers.)

Resume the video when the TV monitor shows the river flowing through the dikes and when the narrator says, "Levees and dikes cause the river to flow in narrower channels."

Pause the video for the last time at the map of Haiti (you will see the capital Port-Au-Prince) and when the narrator says, "One of Land-sat's most important uses is in mapmaking." Ask students to explain how a satellite can help draw a map.

Post-Viewing Activities

1. Image: Mississippi River Delta

Students have a chance to use their imaginations. They are part of a modern day gold rush. Here is the scenario. Gold (Au) is being explored at several sites around the world by using Landsat technology. You have an image-purchasing map. Plot several sites on the map for the mountains of Chihuahua, Mexico.
It has been reported to you as an agent of the Bureau of Land Management that long-time local mining operations with several mineral extraction sites are releasing fast-rushing water into a channel. As a result of the runoff, increased amounts of sediment flow into a nearby river. Examine the image to identify the point of extreme sediment flow into the river's delta.

2. How may Landsat images help the oil in-dustry? Using a geographic map of Alaska, draw the location of the Alaskan Oil Pipe-line.

3. A cruise ship is crossing the North Atlantic Ocean from England to America. The captain has chosen the quickest route. You have a current Landsat data image that reveals the route (15/60) to be unsafe be-cause of sea ice. Draw an alternate route for the captain using latitude and longitude bearings.

Action Plan

Some pine tree farmers of the Carolinas sell timber from their long-term managed forests. Often, it takes 20_40 years for pine trees to reach a maturity stage for harvest.

1. Select images from suggested Web sites. (See Internet Sites.) Analyze the images for drought, disease, fire, or other natural disasters that may plague healthy forests. Explain how Landsat technology benefits tree growers, corn raisers, and soybean farmers.

2. Write to the US Department of Agriculture requesting crop data that was compiled using Landsat technology.

US Department of Agriculture

The Science and Education Division
The Mall
12th & 14th Streets
Washington, DC 20250

Extensions

1. History/Social Studies: Compare and contrast imaging techniques of the 1800s to present-day technology.

2. Math: Predict and decipher…

Which wavelength is the longest?
Which wavelength is the shortest?

Answers:

Blue visible light: 4.5 x 10^-7 meters
Green visible light: 5.5 x 10^-7 meters
Red visible light: 6.5 x 10^-7 meters

3. Physics: Research and arrange the electromagnetic spectrum in order, from the shortest to the longest wavelengths.

Answers:

gamma
microwave
mid-infrared
near infrared
thermal infrared
TV and radio
ultraviolet
visible light
x-ray

gamma
x-ray
ultraviolet
visible light
near infrared
mid-infrared
thermal infrared
microwave
TV and radio

Internet Sites

Carry out the activities listed for the Internet sites below.

1. Evaluate the European and the French satellite systems at their perspective Web sites. List the advantages and select the best imager for studying rural areas and which satellite is best for studying urban environs.

Europe: ERS-1
http://www.esrin.esa.it

France: SPOT
http://www.spot.com/
SPOT Image Corp
1897 Preston White Road
Reston, VA 20191
Phone: 1-703-715-3100

2. EOSAT: Landsat
http://www.spaceimage.com/

How often does the satellite repeat its orbit over the same path? Review the Landsat images and select the Mississippi River. Next, scroll through the data and record the time schedule. Finally, identify the time the Mississippi River's delta was recorded.

3. Best Imager
http://photojournal.jpl.nasa.gov/
http://nssdc.gsfc.nasa.gov/

Write a descriptive paragraph detailing the appearance of vegetation from the space imagers. 4. Advanced Very High Resolution Radiometer (AVHRR)
http://xtreme.gsfc.nasa.gov

Identify mountain ranges, plains, rivers, and lakes.

5. USGS Multispectral Scanner
http://edcwww.cr.usgs.gov/dclass/dclass.html

Observe and distinguish between water and land.

6. Earth from Space Johnson Space Center
http://earth.jsc.nasa.gov/

Identify countries by comparing images and using maps from the social studies or geography textbook.

Glossary

Analog—transmission of a continuously variable signal as opposed to a discretely variable signal. Compare with digital. A system of transmitting and receiving information in which one value (i.e., voltage, current, resistance, or in the APT system, the volume level of the video tone) can be compared directly to the information (in the APT system, the white, black, and gray values) in the image.

Altitude—height above the Earth's surface.

Binary—a numbering system that uses only 1 and 0 (e.g., 1 is one, 10 is two, 11 is three). In digital integrated circuits, a 0 is indicated by a logic low and a 1 by a logic high.

Digital image—a system in which information is transmitted in a series of pulses. The source is periodically sampled, analyzed, and converted or coded into numerical values and transmitted. Digital transmissions typically use the binary coding used by computers so most data is in appropriate form, but verbal and visual communication must be converted. Many satellite transmissions use digital formats because noise will not interfere with the quality of the end product, producing clear and higher resolution imagery.

Grayscale—Environmental satellite scanners, rather than photographing a scene, scan a scene line-by-line, measuring light or heat levels and transmitting this information as a video image via AM subcarrier contained in the satellite's FM signal. The video image—a 2400 Hz tone—is amplitude modulated to correspond to the light and dark areas sensed, with the louder portion of the tone representing the lighter areas of the image and the lower portion of the tone representing the darker areas of the image. This is an analog type of data transmission, and enables the assessment of such features as heat, light, temperature, and cloud heights.

Ground-truthing—a scientific investigation by which an actual site is visited in order to verify the satellite's imagery.

Image—pictorial representation of data acquired by satellite systems, such as direct readout images from environmental satellites. An image is not a photograph. An image is composed of two-dimensional grids of individual picture elements (pixels). Each pixel has a numeric value that corresponds to the radiance or temperature of the specific ground area it depicts.

INSAT—Indian National Satellites

Landsat—Land Remote Sensing Satellite, operated by the US Earth Observation Satellite Company (EOSAT). Commercialized under the Land Remote Sensing Commercialization Act of 1984, Landsat is a series of satellites (formerly called ERTS) designed to gather data on the Earth's resources in a regular and systematic manner. Objectives of the mission are for land use inventory, geological/mineralogical exploration, crop and forestry assessment, and cartography. Landsat has a spatial resolution of 28.5 meters.

Pixel—Smallest part of an electronically coded image, such as a computer display. Pixel is a contraction of "picture element."

Remote sensing—the technology of acquiring data and information about an object or phenomena by a device that is not in physical contact with it. In other words, remote sensing refers to gathering information about the Earth and its environment from a distance, a critical capability of the Earth Observing System.

Resolution—a measure of the ability to separate observable quantities. In the case of imagery, it describes the area represented by each pixel of an image. The smaller the area represented by a pixel, the more accurate and detailed the image.

SPOT—Systeme Pour l'Observation de la Terre. French polar-orbiting Earth observation satellites with ground resolution of 10 meters. The purposes of the satellites are to provide data for environmental research, and monitoring, ecology management.

Swath—the area observed by a satellite as it orbits the Earth.

Thematic Mapper^TM—a Landsat multispectral scanner designed to acquire data to categorize the Earth's surface. Particular emphasis was placed on agricultural applications and identification of land use. The scanner continuously scans the surface of the Earth, simultaneously acquiring data in seven spectral channels. Overlaying two or more bands produces a false color image. The ground resolution of the six visible and short-wave bands of the Thematic Mapper^TM is 30 meters, and the resolution of the thermal infrared band is 120 meters. Thematic Mappers^TM have been flown on Landsat 4 and 5.