"We actively engage with organizations and governments … to strike a balance between their security concerns and the needs of the end user," says Chikai Ohazama, Google Earth's product management director. Sensitive sites often are obscured by satellite operators before Google even gets the imagery, he adds. It often doesn't matter "because the imagery already is available from other places."
The number of sources for satellite imagery continues to grow, fueled not only by government customers in the USA and worldwide, but by an explosion in public usage.
This month, GeoEye launched the most advanced commercial satellite yet — able to distinguish home plate on a baseball field — and the NGA paid half the $475 million cost. Digital Globe will launch a satellite with similar resolution and other new capabilities next year on its own dime.
The use of commercial imagery relieves some of the burden on the U.S. government's classified satellite network, says Rick Oborn, spokesman at the National Reconnaissance Office, which runs the system.
"We're oversubscribed," Oborn says, noting that intelligence and security missions get priority and often need the higher resolution and quicker returns offered by the government's own satellites. "Anytime the broader area stuff can be taken commercially, so much the better."
The appetite for commercial imagery from the general public continues to grow as more people realize the technology has uses far beyond picking out your home on Google Earth.
Non-governmental organizations have used commercial imagery to show devastating attacks on villages in Darfur by the Janjaweed militia. Security experts have used it to show development of new missile bases in North Korea. Environmentalists have used it to document effects of global warming.
"In a way, those sort of things also have a lot to do with national security," says Steven Aftergood, an intelligence expert at the Federation of American Scientists. "It's an extraordinary tool (for) bringing transparency to government. … And it's here to stay."