Military researchers seek ways to 'interrogate' buildings.

[ILLUSTRATION OMITTED]

IN VIETNAM, KOREA and World War II, soldiers and Marines were often ordered to "take the high ground."

But in today's urban battles, buildings have become the new "hills."

Buildings may hide weapon caches, bomb-making factories, enemy combatants or command and control centers--and more often than not--innocent civilians who may have nothing to do with these nefarious activities.

"It is the urban structure that has largely replaced the hilltop as strategic ground," said Martin Kruger, a scientist at the Office of Naval Research.

ONR as well as the Defense Advanced Research Projects Agency and other military labs are looking at sensors that can peer through walls to take away the enemy's ability to hide in the urban landscape.

While self defense is the most practical value in employing such technologies, the larger strategic goal is to expose insurgent enemy networks, Kruger said at an Institute for Defense and Government Advancement conference on urban operations.

To do so, these sensors must be able to "interrogate" a building to discover its "intent," he added. Of course, as inanimate objects, structures don't have "intent," he noted. But they are often chosen for a reason. Their location, shape or amount of space may be suitable for training, recruiting or hiding weapon caches.

Sensors, combined with cultural knowledge of how certain types of buildings are used, can narrow down for commanders the number of buildings that need to be checked out.

Wide area sensors that are currently in development can be mounted on humvees or unmanned aerial vehicles to scan for objects of interest. For example, the presence of long metal cylinders may indicate an ordnance cache. That, combined with data indicating a high rate of improvised explosive device attacks in the same neighborhood, would be cause for suspicion.

To carry out these wide area searches, the lab is working on a high-resolution narrow pulse ultra wideband sensor. The challenges have been cutting out the clutter and displaying the data in a way that is easy for soldiers or analysts to interpret, he said.

Once a suspicious building has been located, a sensor that can more narrowly look at a specific structure to determine who or what is inside is underdevelopment. It sends acoustic energy into a building, then a Doppler radar reads the vibrations and returns data. That would give commanders a better understanding of floor plans, objects, and people inside the building, Kruger said. The two programs are expected to reach advanced testing phases by the end of 2009, he added.

Ideally, a building could be mapped from different angles in three dimensions, from sensors mounted on UAVs, humvees or fixed positions.

If successful, Kruger said these technologies would allow U.S. forces to cut down the time spent unnecessarily entering and inspecting buildings. Units would spend their efforts carrying out other activities. It would also reduce the number of innocent civilians who are aggravated when soldiers or Marines inspect buildings.

"Kicking down doors" has been widely criticized as a tactic that has done little to win the hearts and minds of the populations in Iraq and Afghanistan.

Kruger said two major challenges are the detection of small arms and bulk explosives. There are potential technologies out there, but they aren't yet practical. Marines can't "back an 18-wheeler and have that parked in front of a building for three hours," he said.

DARPA's strategic technology office is working on a similar track with its Visi-Building program, which also seeks to "interrogate" buildings.

It has already fielded a handheld device, the "Radar Scope," which it demonstrated at the DARPATech conference in August. The 1.5-pound device can sense through 12 inches of concrete. A red light indicates whether there is movement or breathing behind walls.

"It can help [soldiers] prioritize what rooms to go into. It will give them an extra degree of knowledge so they know if someone is inside," Visi-Building Program Manager Edward Baranoski told the Armed Forces Press Service.

Berry Fox, deputy director of the joint urban operations office and its principal science adviser, said his office conducted a simulated test of handheld sense-through-wall detectors this summer in Indiana. A National Guard unit was pitted against a local law enforcement special weapons and tactics team who played the part of insurgents holed up in a building.

The friendly force was given simulated handheld devices that told them how many insurgents were lurking behind the walls. The purpose of the exercise was to determine what the "real impact" of such devices might be, he said.

His office has not finished analyzing the exercise, but preliminary results showed that during a running firelight, the National Guard team was too preoccupied with the battle to look at the display.