Mapping Wildfires

NASA is using a new thermal-imaging sensor to track the fires in Santa Barbara.
By Brittany Sauser

Fire map: NASA engineers have developed a new thermal-imaging sensor that can accurately map a wildfire's behavior and pinpoint hot spots. The picture above is a composite of various images taken of a fire near Zaca Lake in Santa Barbara County, CA, on August 16, 2007. The researchers used Google Earth to visualize the data. The bright areas represent the fire’s hot spots.
Credit: NASA

At the onset of a wildfire, the United States Forest Service must deploy its resources as quickly and efficiently as possible to contain and stop the fire. Part of this process involves flying manned missions over the fire to map its location, hotspots, and the direction in which it's spreading. Now a new thermal-imaging sensor developed by NASA Ames Research Center (ARC) is making it easier for researchers to get an accurate picture of the ongoing fires in Santa Barbara. The system is still in development, but the researchers say that it could ultimately save resources, property, and lives.
The U.S. Forest Service and NASA are in the midst of testing the new technology on a remotely piloted unmanned aerial vehicle (UAV) flying over wildfires in California. The flight missions began on August 16, capturing images of a fire near Zaca Lake in Santa Barbara County, and they will continue once a week through September. The purpose of the missions is not only to test the sensor, but also to demonstrate the benefits of UAVs in wildfire tracking, their ability to handle and process data, and their ability to communicate this in real time, via satellite, to receiving stations on the ground.
The key to fighting wildfires is accurately knowing the positional information of a fire--not just taking an image of the fire, but understanding where the fire is and how it's behaving. "If you have one pixel [in an image] that shows there is a thermal heat source there, you need to know the latitude and longitude of that pixel," says Everett Hinkley, the National Remote Sensing Program manager at the U.S. Forest Service and coprincipal investigator on the project. To do so, the researchers use a scanner with a highly sensitive thermal mapping sensor designed by NASA.
The forest service's current system is similar but much less sophisticated: it only measures two portions of the light spectrum. The lack of data on other parts of the spectrum hinders the system's ability to precisely distinguish temperature gradients. The image files captured by the sensor must then be put on a "thumb drive" and dropped out of the aircraft through a tube as it flies near the command station, or the aircraft must land so that the data can be given to a colleague who performs the analysis.
The new equipment includes a 12-channel spectral sensor that runs from the visible spectrum into the reflected infrared and mid-infrared spectrum. Two of these channels were built specifically for the thermal portion of the spectrum and were highly calibrated to be able to distinguish hot spots. This is what makes it an effective wildfire imaging sensor, says Vince Ambrosia, an engineer at NASA ARC and the principal investigator of the fire missions.
The collection of images taken by the scanner is then processed onboard the aircraft in real time, and the data is automatically sent via satellite to a ground station, where it is incorporated into a geographic information system or map package. For the current fire missions, researchers are using Google Earth as their visualization tool. The data is displayed as an array of colors based on their intensity. The temperature ranges might be displayed as red, green, and blue, for example, with the hottest objects colored red. The system's ability to continuously send images of the fire allows researchers to better predict its next move. This helps fire fighters determine where to deploy resources.
The entire sensor package weighs less than 300 pounds and fits under the wing of an unmanned aircraft called Ikhana. Built by General Atomics Aeronautical Systems, Ikhana was acquired by NASA's Dryden Flight Research Center in November 2006. The Santa Barbara mission was the first for the fire-mapping system, but already the researchers are pushing its limits by demonstrating how the unmanned vehicle can collect data continuously for up to 24 hours. NASA hopes to continue using the system for earth-science and atmospheric-science data-collection missions.
"We are trying to augment current capabilities with unmanned aircraft and put them in situations where we wouldn't normally put a manned aircraft, such as dangerous circumstances or night flights at low altitude," says Hinkley. But he says that it will easily be 8 to 10 years before large UAVs, such as Ikhana, will be able to fly over fires on a regular basis, partly because of cost and man power. Currently the Federal Aviation Administration (FAA) requires that a pilot guide the plane from the ground, even though the plane could be programmed to fly on its own. In addition, the FAA hasn't established rules and regulations as to how such planes would fit in the national airspace.
Small, unmanned, aerial vehicles could very soon be used at local incidents, but the sensor technology has to be scaled down to be used on these planes, says Ambrosia.
For the foreseeable future, the U.S. Forest Service will continue to use manned aircraft. Once testing of the new thermal-imaging technology is complete, which is expected within a year, the U.S. Forest Service plans to put the system on its manned aircraft.