Field tests have begun on an airborne system to map wildlands fires being created for the U.S. Forest Service by the Jet Propulsion Laboratory.
Called Firefly, the system charts fires using an infrared sensor flown on an airplane and transmits highly detailed digital maps to firefighter camps on the ground.
The system is sensitive enough to spot a hibachi-sized fire from an altitude of 10,000 feet, and is able to distinguish fire hot spots and other zones of changing fire intensity. The system is also capable of mapping very large fires covering 10,000 acres or more of forest or other wildlands.
While field tests continue in Southern California desert and mountain areas this spring, a prototype of the Firefly system will be turned over to the U.S. Forest Service for use during the 1991 fire season, running from April to October.
Two final versions of the system will be delivered to the Forest Service in 1992.
Firefly makes a great leap in speed and flexibility -- as well as in accuracy of the maps it produces -- over previous systems used by firefighting agencies, according to Dr. J. David Nichols, JPL task manager for Firefly.
Previous fire mapping systems produced a map image on photographic film on the aircraft. Because of the delay involved as the plane returns to the ground, as well as time consumed in manual interpretation of the images, information conveyed to firefighters is often three to six hours old.
Maps produced by older film-based systems also tend to suffer from distortion around the edges of the field-of-view -- making it difficult to locate landmarks in the area of the fire with certainty.
The Firefly system, on the other hand, is able to transmit a highly detailed map -- with such landmarks as firebreaks and waterways clearly placed -- to firefighters on the ground within a few minutes.
Firefly scans the fire scene from the air using a sensor called an infrared line-scan detector. The detector is similar to digital sensors used in cameras on JPL's planetary spacecraft. Instead of measuring light in the visible spectrum, however, Firefly's detector is designed to measure energy at infrared wavelengths. Although invisible to the human eye, these infrared wavelengths convey great amounts of heat from fires.
The Firefly detector produces infrared image data in digital form that are processed by a computer onboard the plane. The computer -- a ruggedized version of a desktop Macintosh -- is able to determine exactly where it is looking on the ground by drawing on a combination of navigation and elevation information.
The navigation system's position data come from orbiting Global Positioning System (GPS) satellites via a special receiver on the airplane. Designed and launched by the U.S. Department of Defense, the GPS system provides marker signals that allow Firefly to pinpoint the plane's position over the Earth.
In addition, the Firefly computer draws on elevation data -- highly detailed information about the altitudes of various points on the Earth below -- from a U.S. Geological Survey database.
As a result, Firefly is able to transmit an extremely accurate map to firefighters on the ground within a few minutes of passing over the fire, Nichols said.
Depending on the equipment on hand at the fire camp, the maps can be printed out in color or using black-and-white symbols to indicate fire intensity.
Each pixel, or picture element, in the final map represents an area of about 45 feet. The accuracy of the system is such that each pixel is within about 300 feet of the actual position on the ground.
Firefly can map an area as large as 10,000 acres without difficulty, Nichols noted. Fire bosses will use its maps to help plan deployment of firefighters and equipment as a blaze progresses.
Field testing of the prototype system is being conducted from a turboprop plane flown from Mojave Airport in the sprawling desert northeast of Los Angeles.
Initial tests will check Firefly's sensitivity and accuracy as it measures small, controlled fires on the flat desert in containers about the size of a backyard barbecue.
Other tests will be flown over the Tehachapi Mountains between Palmdale and Bakersfield north of Los Angeles. In those tests, the system will be used to measure small fires in containers set against a variety of terrain.
In May, Firefly will also make test maps of "prescribed" fires -- pre-planned fires set to burn off hazardous dry vegetation.
JPL engineers will use results of the tests -- and feedback from the Forest Service from its use of Firefly during the 1991 season -- to shape the design of the final system, due for delivery in fall 1992.
Apart from its chief role in firefighting, Firefly's airborne infrared detector has other potential uses, Nichols said.
The device can be used in forestry to chart areas of diseased trees. When disease attacks a tree, the plant's chlorophyll content changes and eventually the heat it radiates is lessened.
Other potential uses for the system could include mapping heat loss from buildings in residential areas, or checking for hot water leaks in pipelines.
Although a hazard in the South and sometimes in the eastern United States, fires in forests and other wildlands are predominantly a menace to the American West -- particularly the Rocky Mountains, the Northwest states of Oregon and Washington, and Southern California.
In 1988, some 75,000 wildlands fires burned a total of 4.3 million acres of land in the United States. Combatting the blazes called on the efforts of 26,700 firefighters from the Forest Service and other agencies.
At JPL, Firefly is a task under the Laboratory's Environmental Technology Program Office, managed by Dr. Minoo Dastoor. Firefly's project manager at the U.S. Department of Agriculture Forest Service in Washington, D.C., is Dr. Mary Jo Lavin.
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