| THE ELEVEN DAY MISSION
There are lots of ways that people make use of topographic data, and for various
parts of the world, maps of Earth's topography are limited, inaccurate, or nonexistent. Lack of
standardization limits the scope of regional or global studies where precise topography is important. |
| Have you ever seen a map that shows not only the location of features on the Earth, but also
how high or low they are? This information is known as topography, and maps which display
elevation information are called topographic maps. |
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There are lots of ways that people make use of topographic data. Scientists use information about
topography to help in their studies of plants and animals. Elevation information provides clues about
soil types, and can tell you how the surface of Earth changes due to the actions of glaciers, rivers,
and the processes of mountain building and erosion. City planners use topographic data to help locate
suitable places for structures or recreation. Aircraft pilots require accurate topographic
information for flight planning and navigation, and the military requires precise topographic
information for training and real time operations. Knowing the exact height and location of mountain
peaks enables the cellular phone industry to place towers in optimal locations for signal reception.
In addition, topographic maps are the mainstay of day hikers and weekend backpackers.
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For various parts of the world, maps of Earth's topography are limited, inaccurate, or
nonexistent. For example, many mountain chains, inhospitable deserts, and dense tropical rain
forests have topographic coverage that is totally inadequate mainly because of the difficulty in
getting to these locations.
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Even where topographic maps exist, they may have been created in such
a way as to limit their usefulness. Neighboring countries may generate topographic data using
entirely different methods. This lack of standardization effectively limits the scope of regional
or global studies where precise topography is important.
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| SRTM used radar instruments to collect data for the most detailed, near global topographic map
of the Earth ever made. For this application, radar is a better tool to use than regular optical
cameras because it can operate day or night and can penetrate cloud cover. Flying the radar on the
Shuttle means that physical access to a site is no longer a problem.
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SRTM payload with mast extended.
"Airglow" is an effect of Earth's atmosphere.
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Using the technique of interferometry, SRTM collect data over 80% of Earth's land mass, home to nearly 95% of the world's population. All of the radar data was collected during a single, 11-day Space Shuttle mission, and will be processed to the same specifications. Collecting and processing the data this way ensures that the SRTM generated topographic maps will have the same characteristics.
The information collected by SRTM will be used to provide a tool to enhance the activities of scientists, the military, commercial, and civilian users.
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