Assertions made last week by the director of the U.S. National Geospatial-Intelligence Agency (NGA) that some censorship of satellite imagery might be necessary for national or military defense stirred questions among experts of whether such restrictions would be either feasible or prudent.

"If there was a situation where any imagery products were being used by adversaries to kill Americans, I think we should act," NGA Director Vice Adm. Robert Murrett told the Associated Press on May 8.

"I could certainly foresee circumstances in which we would not want imagery to be openly disseminated of a sensitive site of any type, whether it is here or overseas," he explained, adding "I think we may need to have some control over things that are disseminated. I don’t know if that means buying up all the imagery or not. I think there are probably some other ways you could do it," he said, deferring specific methods to legal and policy experts.

Some private experts disagree, suggesting that Murrett’s claims for defense might actually do more harm than good.

Once solely operated and used by governments and militaries, information from Earth-observation satellites entered the commercial realm in the late 1990s. Not long after the Berlin Wall came down, Russia began selling satellite imagery on the open market. Two U.S. companies – DigitalGlobe of Longmont, Colo., and GeoEye, based in Dulles, Va. – have launched commercial satellites and compete against commercial and government imagery suppliers from around the globe. With NGA providing funding of about $1 billion, the companies plan to launch more satellites with higher resolutions later this year.

"We’re very close to this subject, and NGA is our biggest customer," said Chuck Herring, a spokesman for DigitalGlobe. "We take it seriously, and work with them very closely."

That said, Herring added that control measures already exist. Both of the remote sensing companies are licensed under the U.S. National Oceanic and Atmospheric Administration (NOAA) within the U.S. Department of Commerce, and NOAA mandates rules for operation, including provisions for shutter control, or preventing imaging over a given geographic area for a given period of time.

"For example," Herring said, "because we’re running at sub-meter (0.6 meter) for resolution, we have to hold imagery for 24 hours, abiding by our license as a sub-meter satellite operator. We also can’t sell to certain individuals and organizations. There are mechanisms already in place, and we work hand-in-hand as it is right now."

Mark Brender, GeoEye’s vice president of communications and marketing, echoed the notion.

"If there’s a threat to national security or a foreign policy concern, than the U.S. government has the authority to interrupt commercial service," he said. "Not since we launched the world’s first high-resolution, Earth-imaging satellite in 1999 has the government ever imposed such imaging restrictions. … Over the years, we have been more than cautious, and we know who our customers are, and our track record is our measure of success."

Herring said discussions about security concerns are as old as the industry, "and probably before that. … If there were concerns, I think we’d have seen them by now. We don’t expect anything to come out of this directly."

That would be just as well, argued consultant William Stoney, of Noblis, a nonprofit science, technology and strategy organization based in Falls Church, Va. Stoney has cataloged all of the world’s civil land-imaging satellites either in orbit or planned to be by 2010 and which offer resolutions equal to or better than 36 meters.

Stoney, a former manager for NASA‘s LandSat program in the 1970s ("when the resolution was 80 meters"), said he is familiar with official resistance to the availability of satellite information.

"They never stop, do they? It’s like pulling teeth every step of the way," Stoney said. "This is the niggling attitude they have. It’s irrational and self-serving in the extreme. Basically they want to send up a military satellite and cut out commercial satellites altogether."

Yet satellites are being continually launched. When GeoEye-1 goes operational, Brender said, it will feature a capability for ground resolution down to 16 inches. "Imagery is only going to get better by the end of this year," he said, adding "and the applications will only increase."

"Google (with its Google Earth service) has really raised awareness to a really high level," Stoney said. "People can see their house and look at where they’re going before they take a trip, et cetera, But [Google doesn’t] update it very often – I think their goal is within two years – especially the stuff they have to pay for. Of course Microsoft (with its competing Virtual Earth technology) is coming through with theirs, too, and adding aerial photography. And [Murrett] thinks they are going to stop that? He’s pushing us toward obsolescence."

While the U.S. companies operate the highest-resolution satellites, other companies and governments own and operate imaging spacecraft. France, Russia, Israel, China and Brazil (in a cooperative agreement between the two) and Nigeria are known to be in possession of the technology, Brender said.

Stoney warned U.S. officials to spend more effort on improving technology than limiting information. "We here in the ‘land of the free and home of the brave’ don’t have any radar satellites, which are changing the whole spectrum of observation," he said. "Europe will soon have nine up with 1-meter data using radar on the open market for everybody. The Germans are about to launch the first of three, the Italians will launch the first of four. Argentina will have one. We’re not in it."

Stoney concluded that "terrorists use cell phones, too. Do we take them away? It’s not our world anymore. This whole business of transparency, I think it’s good. Satellites are not of all that much tactical use anyway. They only come overhead once a day."

J.J. McCoy