On everyone's radar

One of the great interests today is in a radar system that can see through foliage, which can be used to hide enemy positions, says Doc Dougherty, chief scientist at Raytheon's Space and Airborne Systems in El Segundo, Calif. He calls it a "very hard problem" to solve.

Others see great potential in space-based radars on satellites, which could fill in the information gaps other radars miss. And Sandia is also working on radar "tags" that could be mounted on military vehicles, and perhaps eventually attached to every soldier, to identify them as "friendly" forces when they are tracked by their own radars, cutting down on fatalities from friendly fire.

A number of challenges remain, including cutting the cost and preventing enemy forces from disabling, employing, or imitating the sensors.

Meanwhile, in the civilian realm, automakers are exploring radar as the next big thing in safety.

Toyota is putting a radar-based precollision system into its Lexus LS430 luxury sedan. A split second after the onboard radar detects an imminent collision, the car tightens the seat belts around passengers and begins braking.

By the 2007 model year, at least one major carmaker also will be using radar to help drivers change lanes safely, says Scott Pyles, a spokesman for Valeo Raytheon Systems in Auburn Hills, Mich., which is manufacturing the device.

It's based on phased-array radars developed for the military. The unit is mounted in the rear of the car beneath the surface, making it immune to damage from rain, salt, snow, or ice.

Side collisions, caused when drivers fail to see another vehicle in their "blind spot" during a lane change, account for more than 413,000 auto accidents per year and injure more than 160,000 people, Mr. Pyles says. When the Valeo system detects another vehicle or a pedestrian in the driver's blind spot, it activates a LED warning display on the driver's side-view mirror.

"It's a very reliable technology, and you can use it in all weather," he says. He expects "you'll see the price in the $500 to $600 range" or as part of luxury-option packages. The same technology could also be used to provide assistance in backing up and parking, he says.

Further down the road, "long-range" radar may be used to determine the speed of approaching vehicles for situations such as merging into freeway traffic or judging whether a turn across traffic can be made safely. And it's beginning to be used to monitor traffic on freeways, giving traffic planners a real-time view of the number of vehicles, congestion, average speeds, even the sizes of vehicles on the road. Radar's reliability and ability to "see" in any weather make it an attractive alternative to video cameras.

Radar already has brought huge improvements to weather forecasting. Now its newer cousin, "lidar," which uses laser light instead of radio waves, may make even more accurate predictions possible. Unlike radar, lidar has the ability to measure winds without any particulates, such as water vapor, making it able to track so-called clear air.

"Measuring upper atmospheric winds is the No. 1 missing ingredient for making long-term weather forecasts," says Peter Tchoryk, executive vice president of Michigan Aerospace Corporation in Ann Arbor, which is developing a lidar system for doing just that.

With funds from the National Oceanic and Atmospheric Administration, Mr. Tchoryk's company has built ground stations in New Hampshire and Hawaii to test the lidar weather-tracking system. The next step is to launch a high-altitude balloon with lidar to 100,000 feet, a final test before putting the weather tracker into a spacecraft.

From there, it could monitor movements of large weather systems and predict their wind flows.

As a result, seven-day weather forecasts would be just as accurate as today's two-day forecasts.

"It has long-term impacts in terms of agriculture [and] storm and hurricane prediction," Tchoryk says, "not to mention the military aspects of being able to forecast winds."

Lidar is also being used by law- enforcement officers to track speeders on busy highways, where its focused beam lets it easily pick out individual vehicles.

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