sealPurdue News


August 1995

Defense companies looking to use spy satellites for farmers

WEST LAFAYETTE, Ind. -- Remote sensing, a technology often used for spying during the Cold War, will be the next wave in agricultural technology, a Purdue University expert predicts.

The technology is getting a boost as American defense companies convert their electronic swords to cyberworld plows by using spy satellite technology for agriculture.

According to Chris Johannsen, professor of agronomy and director of Purdue's Laboratory for Applications of Remote Sensing, the entrance of defense aerospace contractors into agriculture is causing rapid developments. "It's amazing the number of people who are coming out of the woodwork wanting to get into remote sensing for agriculture and natural resources," Johannsen says. "These people have all the sensors and technology, all of the necessary infrastructure, and they've suddenly lost their best customer. But now they've discovered agriculture.

"But many of these people are just beginning to learn how to spell 'farm.'"

Johannsen says that following the introduction of global-positioning satellite systems and computer-directed variable rate chemical applicators, "remote sensing is the third technology that will earn its way into precision farming."

Currently the only data from remote sensing satellites available to the general public come from government-owned satellites developed by NASA or the French, Japanese or Indian governments.

But TRW has developed a new earth-observing satellite that will be launched in 1996 will have 384 wavelength bands and will be able to distinguish colors in bandwidths as narrow as 3-5 nanometers wide. (A nanometer is one-billionth of a meter.) It will also be able to go beyond human ability by looking for infrared light.

"A satellite having this kind of ability has never been available to us," Johannsen says. "All other satellites have seven or 12 wavelength bands, not 384. That in itself presents several problems that will require research to know what we can do with all of this data."

Purdue's Laboratory for Applications of Remote Sensing joined three other universities, Jackson State, the University of South Carolina and the University of California at Santa Barbara, in working with TRW to develop a proposal for NASA to build the satellite's hyperspectral imaging sensors. The universities will share the data and in developing applications for the technology.

According to Johannsen, these technologies hold great promise for agriculture. "Farmers are already used to using satellite image maps to examine their fields, although they get them weeks or months after the images were taken," he says. "At Purdue we're exploring what would happen if farmers were given the image maps during the growing season, during the first week of June, for example, in less than 48 hours after the image was taken. Could this information be useful? We think it would be."

These remote sensing images will not be the grainy black-and-white pictures familiar to most of us from presidential news conferences. Some of the images look more like Technicolor Rorschach tests than photos from above. That's because the pixilated images indicate various wavelengths of light, including wavelengths outside the abilities of human vision.

Because the color of an object is caused by it reflecting light at a particular wavelength, the hyperspectral imaging sensors will be able to quantify the colors in a farmer's field.

This will do a couple of things for farmers: Instead of just knowing that some of his corn is looking a bit sickly yellow-green out in one corner of his field, he will know that it is emitting light at a specific wavelength. With this information he can consult his research guide of potential problems, or he can turn to diagnosticians at land-grant universities.

"What we will do is look at a green plant's wavelength spectrum, all the way out to the infrared," Johannsen says. "We will be able to identify spikes and other responses in the spectrum due to chlorinating of the plant leaves. If you have a nitrogen deficiency, for example, you would have less chlorophyll and you would have a spike."

Other problems will be evident from the color spectrum analysis, too. "A farmer will get a map that shows a main element deficiency caused by a pH imbalance, for example, or it might show that part of the field is showing symptoms of drought, which could be caused by dry soil or might be caused by weeds," he says. "The map might show other signs of stress, such as a weebeastie chewing on the roots."

In addition to the TRW satellite, Space Imaging, another company that has been set up by a group of defense contractors, including Lockheed, will be launching a remote sensing satellite soon.

Also, this summer Rockwell International Corp. will release a precision farming system that employs global positioning satellite systems. The hardware and software package is called Vision System, and it was tested by more than 50 farmers on corn and soybean fields last fall.

"This sort of careful analysis fits the pattern of the aerospace industry," Johannsen says. "I just have to applaud them and welcome them to agriculture. These people will learn how to spell 'farm' soon enough, and then those of us in agriculture are going to learn quite a bit from them."

Defense companies aren't the only way the military is influencing this pocket of agricultural research. Many of Purdue's top graduate students working in the Laboratory for Applications of Remote Sensing are veterans of the Gulf War with Iraq who are familiar with the technology.

"We're supposed to be the professors, but we're learning quite a bit from some of these students," Johannsen says with a laugh.

Purdue's Laboratory for Applications of Remote Sensing conducts research in global positioning satellite systems, global information systems and remote sensing for application in the areas of agriculture, natural resources and the environment.

Source: Chris Johannsen, (765) 494-6305; home, (765) 463-7641; Internet,

Writer: Steve Tally, (765) 494-9809; home, (765) 463-4355; Internet,

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