The widespread devastation caused by Hurricane Katrina is being measured and documented by an array of military, intelligence, civil and commercial satellites and aerial sensors.

Satellites operated by the U.S. Defense Department, NASA and commercial remote sensing firms have been training their sophisticated instruments on the battered Gulf C oast since before the storm hit there the last week of August.

The Federal Emergency Management Agency (FEMA) and other U.S. government agencies responsible for dealing with the disaster were also able to make immediate use of satellite imagery collected by foreign satellites thanks to a five-year-old international charter crafted in anticipation of just such a disaster.

U.S. government officials and other experts said Katrina marks the first time the United States has invoked the United Nations-brokered “Charter on Cooperation to Achieve the Coordinated Use of Space in the Event of Natural or Technological Disasters.” The Charter was created to help countries dealing with a natural or man-made disaster get assistance from nations with satellites.

The U.S. Geological Survey’s Center for Earth Resource Observation and Science in Sioux Falls, S.D. served as the central clearinghouse for all imagery of the storm-ravaged Gulf Coast, including imagery flowing in under the charter from French, Canadian and Indian remote sensing satellites. The EROS posted the imagery to its website for use by all governmental and non-governmental agencies responding to the disaster. The U.S. National Geospatial-Intelligence Agency (NGA), meanwhile, plays a key role by merging both classified and commercial satellite imagery and turning it into graphics useful to emergency responders. It has been working with FEMA to survey the extensive damage to cities, towns and other infrastructure along the U.S. Gulf Coast and speed; that information to all of the relevant organizations involved in responding to the emergency.

NGA is using imagery captured by commercial remote sensing spacecraft and spy satellites operated by the National Reconnaissance Office to piece together before-and-after pictures that document the devastation the hurricane inflicted on coastal Alabama, Louisiana and Mississippi as it made landfall Aug. 29.

“Observers on the ground provide a close-in view of a disaster. Aircraft can provide a broader view. But NGA using our satellites — U.S. government and commercial — provides a different view,” said Howard Cohen, an NGA spokesman. “With these satellites NGA provides FEMA with geospatial information that can cover the affected states. With information provided by these assets FEMA is better able to make assessments on the overall damage and decide where to focus resources,” he said.

By the time Katrina made landfall, NGA already had produced 100 graphics depicting key infrastructure — highways, airports, hospitals, police and fire stations, schools, and hazardous material locations — in the path of the storm, according to Cohen.

NGA also dispatched 26 analysts and two mobile geospatial intelligence units — computer-laden Humvees — to provide on-the-spot support to FEMA and other U.S. government agencies in the disaster zone. These on-the-scene analysts, according to NGA, have produced more than 200 geospatial information products depicting, for example, damage to the region’s transportation infrastructure.

While some of the imagery was collected by classified government satellites, much of it was collected by commercial high-resolution remote sensing satellite operators.

Digital Globe of Longmont, Colo. , Orbimage of Dulles, Va., and Space Imaging of Thornton, Colo., have been busy targeting the zones of destruction left by Hurricane Katrina, forwarding the imagery to NGA under the auspices of the agency’s two-year-old ClearView data purchase agreement.

John Perry, FEMA’s geospatial information systems and remote sensing coordinator here, said satellite imagery and aerial photography are critical to the government’s disaster response and recovery efforts.

Perry said satellite imagery, however, is only as valuable as the interpretation brought to it — and that, he said, is where NGA excels.

“Having a background image is nice, but the exploitation is really critical,” he said.

Perry said FEMA uses satellite imagery to make an initial damage assessment following a disaster. By combining imagery with other data — population information, for example — FEMA can make some quick decisions about how to prioritize its response. Once responders are on the ground, satellite imagery and aerial photography is useful for planning rescue operations, helping FEMA and other agencies, for example, plot viable transportation routes.

NASA also did its part to help assess the scope of the damage and the environmental impact of the hurricane and resulting widespread flooding.

Ron Birk, a senior NASA official in charge of Earth science applications, said the U.S. space agency’s Earth-observing satellites and airborne science instruments have been providing insight into the environmental impact of Hurricane Katrina, returning images and data that is helping characterize the extent of flooding; damage to homes, businesses and infrastructure; and potential hazards caused by the storm and its aftermath.

A NASA Cessna 310 took to the skies three days after the storm to survey the ravaged gulf coastline with the agency’s Experimental Advanced Research Light Detection and Ranging system, a high-resolution imager capable of peering through vegetation and flood waters to see the ground beneath. Two days later, the Cessna flew over New Orleans using the high-resolution imager to help assess the damage to the city’s breeched levee.

NASA’s Aqua, Terra and Earth Observer-1 satellites trained their instruments on the region, providing imagery for FEMA and other government agencies through the U.S. Geological Survey’s National Center for Earth Resources Observation and Science Data Center, Birk said.

NASA’s Tropical Rainfall Measuring Mission also helped hurricane forecasters predict the amount of precipitation Katrina would bring as she battered the Gulf Coast and moved inland. That satellite, incidentally, would have been shut down last year if U.S. lawmakers had not intervened.

Birk, agreeing with FEMA’s Perry that satellite imagery is only as useful as the interpretation, said NASA-funded researchers have been doing their part producing value-added imagery products helpful to emergency responders. For example, the University of New Hampshire’s Dartmouth Observatory produced a flood inundation map of the Gulf Coast similar to the graphics it produced last December when an Indian Ocean tsunami killed hundreds of thousands of people in island and coastal Asian nations.

Perry said FEMA likely will have a strong presence in the affected Gulf Coast states for many months to come and that satellite imagery will continue to make important contributions to the recovery and rebuilding effort.

Like Birk, he said universities have an important role to play. Louisiana State University in Baton Rouge, for example, is establishing a data clearinghouse for remote sensing imagery there for anyone who needs it as Mississippi and Louisiana undertake the arduous task of rebuilding their battered communities.

Leonard David contributed to this report from Boulder, Colo.

Brian Berger is editor in chief of and the SpaceNews magazine. He joined in 1998, spending his first decade with the publication covering NASA. His reporting on the 2003 Space Shuttle Columbia accident was...