Liftoff to Learning: Geography From Space
Table of Contents
The primary payload of STS-59 was the Space Radar Laboratory. Radar emissions from the laboratory were directed at Earth's surface and their reflections were then recorded. Scientific researchers, policy makers, and military operations require information about specific regions of Earth that may be difficult to obtain due to blocked views or remote locations. The ability to see and gather information about objects hidden from optical observation is the driving motivation behind radar imaging from space. One of the most useful features of radar imaging is its ability to make measurements over virtually any region at any time, regardless of weather or sunlight conditions. It is able to penetrate cloud cover and provide its own source of illumination. At some frequencies, radar waves can also penetrate through vegetation, some types of snow, and extremely dry sand.
The STS-59 mission lifted off from the Kennedy Space Center on the 62nd Space Shuttle flight carrying to space the Space Radar Laboratory-1 (SRL-1 ) payload as part of NASA's Mission to Planet Earth program. SRL consists of the Spaceborne Imaging Radar-C/X- Band Synthetic Aperture Radar (SIR-C/S- SAR) and a sensor to measure carbon monoxide distribution in the lower atmosphere. SIR-C/ X- SAR (actually five separate radars) also contained the Data Processing Assembly to provide direct readout of ocean surface data. SIR-C/C-SAR was jointly developed by NASA, the German Space Agency (DARA), and the Italian Space Agency (ASI). NASA developed the SIR-C (Land C-band radars). DARA and AST developed the X-band system, and all three participated in the integration of these radars into a single instrument, the SIR-C/X-SAR. The Measurement of Air Pollution from Satellites (MAPS) instrument, developed by the NASA Langley Research Center, studied the presence of carbon dioxide in the troposphere. NASA will distribute the data and findings of these experiments to assist the international scientific community in essential research for protecting the environment.
Once the crew was in orbit, they powered up the SRL-1 payloads and conducted a checkout of the experiment systems. Ground controllers uplinked commands to begin radar observations during the 11-day flight. The crew worked in two shifts around the clock to conduct Earth photography and personal observation of weather and environmental conditions to compare to the SRL data after the flight. To aid in postflight data interpretation, the crew documented site conditions by maintaining a written log and taking nearly 14,000 photographs with several cameras and lenses. The crew also performed 412 attitude maneuvers, the most of any Shuttle mission to date, to reduce radar ambiguities, particularly in the X-band frequency radar. The mission resumed approximately 47 terabits (47 trillion bits) of data- the equivalent of 20,000 encyclopedia volumes.
The SRL examined over 400 sites on Earth, 19 of which were designated as "supersites." These sites were high priority focal points for data collection. Each supersite represented different environments within the scientific disciplines of ecology, hydrology, oceanography, geology, and radar calibration. As such, these are areas where intensive field work has occurred before, during, and after the mission. The supersite locations for ecology included: Manaus, Brazil; Raco, Ml.; Duke Forest, NC.; and Central Europe. The supersite locations for hydrology included: Chickasha, OK.; Otzal, Austria; Bebedouro, Brazil; and Montespertoli, Italy. The supersite locations for oceanography included: Gulf Stream, mid-Atlantic; Northeast Atlantic Ocean; and Southern Ocean. The supersite locations for geology included the Galapagos Islands, Sahara Desert, Death Valley, Andes Mountains, and Hawaii. Oberpfaffenhofen,Germany; Kerang, Australia; and Flevoland, The Netherlands were the calibration sites.
Ecologists will use the radar images of the tropical rain and temperate forests to study land use; the volume, types, and extent of vegetation; and the effects of fires, floods, and clear cutting. Hydrologists will use the data to study wetlands and snow cover to estimate the soil moisture. "Hidden" water plays a major role in determining whether a region is wet or dry and influences the global distribution of energy. Oceanographers will use the data to study how the Earth's climate is moderated by the ocean, particularly heat-transporting currents like the U.S. Gulf Stream. Geologists will use the data to map geological structures and rock formations over large areas. They can also use the data to continue studies of features that record past climate changes. On a previous shuttle flight, SIR-A demonstrated the ability to penetrate extremely dry sand and discovered ancient river channels in portions of the Sahara Desert.
Space Geography On The Internet
Materials: Computer workstation connected to the Internet, image processing software (NIH Image, Photoshop, etc.), and a world atlas.
Background: Since the beginning of the space program, NASA has collected hundreds of thousands of photographs of Earth as seen from space. Many of these pictures are accessible electronically through the Internet. Because the pictures were collected over more than a 35-year period, they provide an excellent database for studies on global surface changes.
Procedure: Use the following Internet addresses to connect to the NASA photo libraries. Choose a particular subject for study (e.g. rivers) and identify a study site from the world atlas. Search the NASA photo libraries for pictures that cover your study area. Try to select areas that have been photographed several times over a period of years. Identify the major surface features seen in the picture. This job will be much easier if the study area is a place with which students are already familiar. Compare older pictures to newer ones to look for possible changes. Use image processing software, if you have it, to analyze each picture. Write an analysis of the pictures and the changes that have taken place.
Move it so that the plane of the disk passes directly through Earth's center. Look at how the rubber band is inclined to Earth's equator. Place a second rubber band around the globe so that it runs through the launch site and is inclined at approximately 57 degrees
to the equator. This is the highest Shuttle inclination flown. Imagine that the orbit of the Shuttle is 300 kilometers above Earth's surface. How high would the Shuttle be above the globe? To do this, students will have to figure out the scale of the globe and then determine how high the Shuttle would be if placed at its scale altitude. (Earth's diameter is approximately 12,740 kilometers.) Hold the globe near a student's eye at the scale distance of the Shuttle's orbit. Ask the student to estimate how much of the Earth is visible at one time. What would happen if the Shuttle's altitude were doubled? Why is it that the Arctic and Antarctic regions of Earth are not studied by Space Shuttle astronauts?
To obtain biographic information, click on highlighted names