US Secret Service airbrushes aerial photos

Call it the case of the missing White House. Users of Mapquest's free aerial photo database recently noticed that details of several Washington D.C. government buildings were no longer discernable in overhead images of the U.S. capital.

A comparison of old and new images posted on the government secrecy watchdog site Cryptome shows that portions of overhead color photos of the Capitol building and the grounds of the Naval Observatory, where the Vice President's residence is located, have been distorted -- pixilated into an digital blur.

The White House and the adjacent Old Executive Office Building and Treasury Department headquarters were subject to more subtle tampering: the buildings are still sharp, but the roofs have been digitally painted over with featureless solid colors seeming picked from the surrounding landscape. The lot at 1600 Pennsylvania Avenue now resembles a White House-shaped dirt field more than the seat of executive power.

But the modifications weren't performed by America Online's Mapquest, nor by the company that, until recently, provided Mapquest with aerial imagery. "We're surprised to see that," says Chris Becwar, spokesman for California-based GlobeXplorer. "We have other layers of imagery over D.C., and none of them have ever had this done to them. This is definitely a new thing."

It turns out the changes were made by EarthData International of Maryland, the company that took the aerial photos under contract with the U.S. Geological Survey, according to USGS, which commissioned the images for the National Aerial Photography Program, an ambitious multi-agency project to gather and organize high-resolution overhead imagery of the entire United States for scientific and cartographical use. (EarthData couldn't immediately comment.) USGS sells paper and digital copies of individual images to the public for a modest fees, and offers them in bulk to companies like Globexplorer, which combine them with other privately-produced images and resell them.

The digital airbrushing was done at the request of the U.S. Secret Service, the agency charged with protecting the President and Vice President.

"The contractor went through the Secret Service to get permission to fly over the restricted airspace that was required to get those photos, and my understanding is that the photos were degraded at the request of the Secret Service," says USGS spokesman Scott Harris. "We don't ever alter any of the imagery that we take... The resolution of that photography isn't particularly sensitive."

"As with other agencies with responsibilities in the area of critical infrastructure and facility protection, the Secret Service is concerned about images that may expose operational security assets," said Secret Service spokesman Thomas Mazur, in a statement. "The Secret Service acknowledges our participation with the U.S. Geological Survey, and their contractors, on this mapping project. Our participation in projects such as these is to ensure the safety and security of the people and the facilities we are responsible for protecting."

The Secret Service did not say what kind of threat accurate overhead imagery poses. But Gartner analyst John Pescatore, a former Secret Service agent, says the image distortions could be a response to real, if unlikely, attack scenarios: like a homemade drone aircraft armed with explosives, remotely piloted by a terrorist using aerial photographs as a navigation aid. "There are actually good reasons, oddly enough," says Pescatore. "Some of them are very low probability things."

The White House is also known to have black-clad snipers on the roof waiting to pick-off attackers, but Pescatore says keeping their positions secret probably isn't a consideration. "They try to be very visible, because it's actually the visibility that scares away the bad guys," he says.

Overhead images of the same sites taken as recently as last year are still easily found online and in print -- a detailed shot of the White House roof even adorns a glossy government brochure on the National Aerial Photography Program. "It is not as if aerial imagery of the White House is hard to come by," says Stephen Aftergood, director of the Project on Government Secrecy at the Federation of American Scientists. "Except in the case of unacknowledged government facilities, it is hard to see what is gained by this policy, and the downside, I think, is that it encourages public paranoia."

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