Joseph M. Kirman
When the Canadian Space Agencys Radarsat Satellite was blasted into orbit by NASA in 1996, a new tool became available for teaching geography. Radar images of the earths surface taken from almost 800 km high could now be made and continuously repeated for a given location for 24 days. What makes Radarsat so unique among the various satellites now providing images of the earthsuch as Landsat and SPOTis that these latter satellites sensors are limited to reflected daylight and cannot penetrate cloud cover. Radarsat images do not have this limitation; they can image areas beneath heavy clouds and on the dark side of the earth. Radar also provides superior images of the earths surface geology.
The technical name for interpreting satellite images and aerial photographs is remote sensing. This means to examine something without touching it. Children can easily grasp this concept by thinking about their own vision. The human eye is a remote sensing sensor, and a photograph it examines is a remote sensing product.1 Recent research has shown that Radarsat images can be used effectively with fifth and sixth grade children.2
What Can Be Observed on Satellite Images?
Earth resources satellites based on remote sensing, Landsat and Radarsat among them, now continuously monitor the surface of the earth.3 These satellites operate in a near Polar orbit, moving from North to South Pole and back again in a path offset slightly from the Poles.
Earth resources satellites provide a timely view of such phenomena as seasonal change; agriculture; animal habitats; deforestation; hydrology conditions; iceberg locations; surface geology; the incidence of pollution; and the before, during, and after of natural and human-made disasters. An image of a situation while it is happening can only be made if the satellite is over the location.
Children may be especially taken with the archaeological uses of satellites. These include finding and observing ancient historical sites, such as the lost city of Ubar.4 Radar signals have also penetrated sand that was perfectly dry to locate ancient riverbeds beneath deserts.
How Does Radarsat Obtain an Image?
Radarsat resolution varies from a high of 9 to 100 meters, and can cover an area varying from 50 to 500 kilometers; the smaller the area covered, the higher the resolution.5 Radarsat images appear in tones of black, white, and gray. The radar sensor is an active one that sends a radar beam to earth and records what is reflected back. Where there is no reflection, the location will show black. Where there is a return, the image will show white or shades of gray.
The more reflective a surface, the brighter it will appear on a Radarsat image. A surface that angles the radar beam toward the satellite will make that location appear brighter.
A surface that angles the beam away from the satellite will make that location appear
darker or speckled. For example, a radar beam bounced off the corner of a building will appear very bright, while a beam hitting flat ground will be scattered and produce a darker image depending partly on what is on the ground. Water is a poor reflector of radar and appears black, while a ship, sandbar, or island will appear brighter against this background.
Previous Research on Remote Sensing
Previous research on the ability of children to interpret remote sensing images has shown that third, fourth, and fifth grade children are able to interpret both gray tone and color Landsat images at a scale of 1:1,000,000,6 and that fourth grade children can interpret infrared vertical aerial photographs in combination with Landsat images.7
Landsat images with scales of 1:1,000,000 and 1:250,000 were used successfully in a sixth grade study of the Mount Helens volcano eruption.8 Sixth grade children have also proved able to interpret Landsat satellite color images with computer assisted instruction,9 understand the principles of digital data and pixels associated with the production of Landsat satellite images,10 and operate a computer program using Landsat digital data to derive ground information.11
What Can Upper Elementary Children Identify Using Radarsat?
Fifth and sixth grade children have been able to identify many features of the urban landscapeincluding buildings, streets, rivers, bridges, cars, and golf coursesusing Radarsat fine beam mode images with a 9 m resolution and a 50 km area. They can identify more items when these are shown on a specially-marked Radarsat image. In fact, using such images is a good way to introduce children to interpreting radar imges.
One recommended class activity is to provide children with a street or road map that is not brand new, and ask them to compare it with a recent Radarsat image of the same area. What appears on the satellite image but not on the map? Children may discover such items as a new bridge, shopping mall, or sports stadiumor perhaps even their own school. Another interesting exercise is to ask students to examine the land at the edge of their town or city, and to hypothesize about the impact of future growth on this land.
Radarsat images of mountain areas, used in conjunction with photographs and contour maps, can add a dramative visual component to the study of geology. A map scale equal or close to that of the Radarsat image should be used, unless the objective is for children to work with different scale representations of a location.
Since the Radarsat CD-ROMs used by researchers and industry are presently too expensive for classroom use, the following free or low cost items are suggested for teacher and/or student use.
Distance RADAR Learning Program with Radarsat Imagery
This CD-ROM is the digital book version of the Radar Distance Learning Program. It provides a comprehensive introduction to space borne synthetic aperture radar (SAR) technology for those without specialist ability, and allows professionals to assess this technology for their own research. Cost: free. Contact: Geomatics International, 3370 South Service Road, Burlington, Ontario, Canada, L7N 3M6. Telephone: (905) 632-4259.
E-mail: email@example.com; Website: www.geomatics.com.
Radarsat Image Samples
This CD-ROM contains more than 30 sub-scenes with text showing different applications, types of terrain, and Radarsat beam modes and incidence angles. There are seven scenes in all, including three full scenes which are capable of manipulation; processing software; a processing program; PCI Image Handler; CEOS Reader; and additional programs. Cost: $5.50. Contact: Radarsat International, Client Services, 3851 Shell Road, Suite 200, Richmond, British Columbia, Canada,V6X 2W2. Telephone: (604) 244-0400. Fax: (604) 244-0404. E-mail: firstname.lastname@example.org.
The RADARSAT International website (www.radarsatinaction.com) contains a large number of worldwide Radarsat images for classroom examination.
RADARSAT Monitors Natural Disasters: The Red River Flood of 1997
This CD-ROM shows how Radarsat satellite images were used to monitor the Red River flood of 1997. It includes a number of worldwide images showing applications of Radarsat satellite data ranging from geology, forestry, and agriculture to monitoring ice conditions. Users of this CD-ROM must have an Internet browser. Cost: $10. Contact: Radarsat International (address above).
1. A NASA Internet site providing an introduction to remote sensing is found at octopus.gma.org/surfing/sensing/index.html; an Internet remote sensing tutorial is available from the Canada Center for Remote Sensing at www.ccrs.nrcan.gc.ca/eduref/tutorial/tutore.html.
2. Joseph M. Kirman, The Ability of Grades Five and Six Children to Use Radarsat Satellite Images in Geography Instruction. Presentation to Canadian Space Agency ADRO (Application Development and Research Opportunity), Final Symposium, Montreal, October 15, 1998; Joseph M. Kirman and Lorna Nyitrai, The Ability of Sixth Grade Children to Use Radarsat Satellite Images, Journal of Geography 97 (March/Aprill, 1998): 56-62.
3. Earth resources satellites are designed to monitor the surface of the earth. They differ from so-called spy satellites, which have a very high resolution image and are capable of imaging very small objects. These latter types of satellites are in an equatorial orbit and can be maneuvered from earth.
4. An Internet site dealing with the remote sensing search for the lost city of Ubar is found at observe.ivv.nasa.gov/nasa/exhibits/ubar/ubar_0.html
5. Canadian Space Agency, RADARSAT:ADRO Program Announcement Volume IIRADARSAT System Description. Canada: Canadian Space Agency, NASA, Radarsat International, 1994.
6. Joseph M. Kirman, The Use of Infrared False Color Satellite Images by Grades 3, 4, and 5 Pupils and Teachers, Alberta Journal of Educational Research 23 (March 1977): 52-64; Use of Band 5 Black and White Landsat Images in the Elementary Grades, Journal of Geography 80 (November 1981): 224-228; A New Elementary Level Map Skill: Landsat Band 5 Satellite Images, Social Education 48 (March 1984): 191-195.
7. Pearl A. Gyan, Multistage Remote Sensing with Grade Four Students, Masters Thesis, University of Alberta, 1984.
8. G. E. Smith, Remote Sensing with Academically-Talented Grade Six Students, Masters Thesis, University of Alberta, 1982.
9. Brian Thomas Burke, A Landsat Color 1 CA1 Program for Grade Six Students, M.Ed. Thesis, University of Alberta, 1983.
10. Joseph M. Kirman and Maria Unsworth, Digital Data in the Grade 6 Classroom, Journal of Geography 91 (November/December 1992): 241-246.
11. Joseph M. Kirman and Chris Jackson, Grade 6 Childrens Ability to Use a Landsat Digital Data Computer Program, Journal of Geography 93 (November/December 1993): 254-262.
Research and data for this article was sponsored by the Applications Development and Research Opportunity Program of Canada Space Agencys RADARSAT Project, RADARSAT International, and the University of Albertas Social Science Research program.
Joseph M. Kirman is professor of social studies in the Department of Elementary Education and director of Project Omega for Research in Remote Sensing and Aerospace at the University of Alberta, Edmonton, Canada.
©1999 National Council for the Social Studies. All rights reserved.