Data Center Uses Photos to Battle Pests, Crop Disease

Through Space Age technology and research, an obscure federal facility on the South Dakota plains has had a dramatic impact on weather forecasting and crop management around the world.

The EROS Data Center, short for Earth Resources Observation Systems, was established near Sioux Falls in 1972 and is the world’s foremost source of remote-sensing data obtained through high-altitude photography and satellite transmission.

“We are the nation’s archive for civilian satellite imagery and for all of the NASA high-altitude aircraft imagery as well,” said Dennis Hood, acting administrative officer.

“We also have NASA’s Apollo and Gemini shots and a variety of special-purpose imagery, like from Mt. St. Helens,” he said. “We have something like 10 million frames of data.”

Those millions of frames of high-altitude photography and digital-tape imagery, some of it just hours or days old, has been used in projects ranging from pest control in Africa and crop disease control in Central America to surveys of the damaged nuclear reactor at Chernobyl in the Soviet Union.

Some of the EROS-produced images appear surrealistic because of “false-color” adjustments, which avoid the blue, or light-scattering end of the spectrum. If it were not for this capability, many of the images would look like the cloud-swirled global satellite shots used on television weather shows.

Where the natural spectrum would show blue, green and red, the altered image shows green, red and near-infrared. Near-infrared appears dark red, almost purple. Vigorous and healthy vegetation looks red.

In one project still awaiting funding, researchers at EROS and South Dakota State University are working with sugar producers in Belize to control a disease that is gradually destroying the sugar cane crop in that Central American country.

Through ground surveys, crop sites in various stages of degeneration will be identified and mapped. These sites will then be used as control groups when the researchers examine images transmitted from NASA’s Landsat satellite to a receiver dish at the EROS facility.

“We want to look at the images and determine four or five classes according to the percent of infection,” said Ken Dalsted, associate acting director of remote sensing at SDSU. “Then they can see which crops to pull out and replant with a hardier strain.”

Dalsted said it will take about two years to determine if the research is effective. If it goes well, a model will be developed for use in Venezuela, Jamaica, Guatemala and the southern United States, areas infected with the same disease.

EROS technicians also use satellite data to produce maps for pest control in Africa.

“We’re collecting data on a daily basis over the countries of Niger, Chad, Mauritania, Senegal and Gambia over a two-week time period,” Steve Howard said.

“We then compile the data to get an idea of the vegetation conditions, primarily to help with the grasshopper-monitoring problem. It gives them an idea where the pockets of vegetation are where they may be breeding.”

Howard said the maps are sent air express to Africa, where local crop managers take them into the fields. The images are so precise that individual bushes and trees can be seen. One of the more striking exhibits at the facility is a series of prints showing the progressive overheating of the Soviet Union’s Chernobyl nuclear plant.

Hood said the prints, which show vivid purple clouds of radioactive steam rising from the site, were produced by combining data with high-resolution spot satellite data from a French facility somewhat like EROS.

The effect is similar to a print made from two sandwiched negatives, one fairly sharp, but black and white, and the other out of focus, but in color. The color indicated the areas of relative heat or coolness.

“We can see here the four reactors and from the thermal indications we can point out the hot one, which shows here as purple,” Hood said.

“We compare the cooling patterns under normal operation, then shortly after shutdown, then at a later date when it’s all cooled. We can see the changes.”

Hood said EROS has had a rocky existence, from originally being suspect because people did not understand the center’s function, to fights for continued funding under tighter federal budgets.

He feels best about accomplishments at EROS when the facility is able to “work itself out of business” by adapting emerging technology to a variety of uses, simplifying the processes and teaching other researchers and educational institutions how it can be used.