Cell towers can spot stealth planes

Associated Press

WASHINGTON — America’s stealth bombers may be in danger of having their cover blown by a new type of radar that uses cell phone technology, researchers say.

The Air Force says it’s a limited problem and America’s unique stealth fleet is in no danger. Yet, U.S. intelligence reports label the radar a serious threat, and several scientists agree.

"We’re talking about radar technology that can pinpoint almost any disturbance in the atmosphere," said Hugh Brownstone, a physicist at the Intergon Research Center in New York who has worked for the cell phone giant Nokia.

"You might not be able to distinguish between a stealth plane and a normal one, but you might not need to. The point is, you can see the stealth plane as a blip," he said.

The potential risk comes from radar towers used by cell phone companies to draw in signal patterns. The new technology, called passive radar, watches signals from common cell phone transmissions. When a plane passes through, it leaves a hole in the pattern, giving away its location.

Traditional radar, the kind stealthy B-2 and F-117A bombers can fool with their angles and radar-absorbing paint, sends out signals and waits for them to bounce off large objects in the sky and return.

Some aviation experts suspect the Serbs used a rough version of passive radar, plugging computers into their existing air defense system, to locate an F-117A Nighthawk stealth bomber, shot down in 1999.

There are more than 100,000 cell phone towers and other sites in the United States. Industry analysts estimate there are 210,000 sites in Europe. The rest of the world is unevenly covered, but even the smallest and poorest nations often have some cell phone towers.

The passive radar system has drawbacks. It can’t effectively pinpoint whether a plane is a stealth craft or some other aircraft, scientists say. It’s also much more difficult to make work.

A major hurdle is the complex math necessary to translate cell phone signals into easy-to-understand blips that move across a computer screen. Without the computer programming to make sense of the cell phone signals, it would be impossible to fire a missile at a plane.

Still, the passive radar technology is basically sound, said Nick Cook, an aerospace consultant for Jane’s Defence Weekly.

"It needs further work, but the theory is there," he said. "Still, it would be some time before I could imagine something like this compromising stealth technology completely."

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