Earth Resources Observation Systems

Sioux Falls, SD

June 7th, 2002

Having been traveling now for some 5 years or so, we have found ourselves constantly dealing with places we have never been and have no knowledge of the requirements of getting around.  The use of maps has become an everyday occurrence.  We even use a computerized mapping program, run on a laptop computer as we drive along.  Did you ever wonder where all that mapping information came from?  All those roads through all those towns drawn to perfect scale, and all those topographical maps with their lines of similar elevation, so precise in every detail? I found the answer to that question and much more at EROS which stands for Earth Resources Observation Systems; a US government operation with a medium strength security system.  I was met at the front door by a very well armed guard who politely but thoroughly went through my camera case, even to the point of requiring that the camera be turned on so he could see the image on the back.  With this out of the way I was off wandering down the long corridor on a self guided tour.  The walls were lined with photographs taken by satellite with different magnification and different light medium. There were pictures taken with infrared and ultraviolet, and some were done using methods I had never heard of before.  Acting as a division under the U.S. Geological Survey, EROS holds one of the world's largest collections of images of the Earth's land surface. It also has the responsibility of distributing these images to scientists, policy makers and educators worldwide.  It is one of the five field centers operated by the National Mapping Program of the USGS which in turn is under the Department of the Interior.  The data is gathered by two methods.  Information on the US comes from photographs taken by aircraft.  Information on the rest of the world is received through an assortment of satellites under the control of various civilian agencies.  In the middle of the hallway was a gigantic camera once used to photograph the earth. It went up aboard the Space Shuttle Challenger in Oct of '84.  The pictures were great but very expensive and the camera was abandoned soon after.  Today EROS manages about 8.5 million photos taken by aircraft and some 4.5 million taken by satellite.  Much of the data for satellite comes from a machine called Landsat. The information is received through a giant antenna housed in a large round structure in the rear of the building. The camera on board is so powerful that it can obtain a resolution down to 45 feet for black and white photos and around 95 feet for color.  In addition to making maps for just about anywhere, the material gathered is used in comparison with photos taken earlier to see changes in the Earth's surface.  Such things as urban growth or the spread of a wild fire can be quickly checked and the information passed to those with a need to know.  So the next time you pick up a road map or dial up a mapping program on your computer think about all the work that went into just getting the information that appears on the paper.  It was an interesting place for the technically minded and a neat way to find out just how things happen.

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