Pentagon bizarro-tech chiefs have issued a requirement for mysterious sensor systems which would be able to peer through concrete walls to produce a complete internal picture of a building. US Forces would use such kit for "overseas urban building interior awareness".

The new plans are known as "Comprehensive Interior Reconnaissance", and come - of course - from famed off-the-wall military tech bureau DARPA, where they believe it's better to invent a head-mounted multispectral imaging device than curse the darkness. The Pentagon brainiacs note:

As overseas military and peace-keeping operations have expanded in urban environments, our adversaries have adopted asymmetric strategies such as hiding in and operating out of civilian buildings ... it is imperative that we develop technologies to allow US Forces to confidently manoeuvre within urban interiors whether above or below ground ... Once specific buildings have been identified as deserving closer scrutiny, our forces [will] concentrate specific resources on these buildings to support tactical planning. Deployed sensors can spend more time providing detailed situational awareness of a single building, determining its floor plan, underground extent, and underground ingress and egress ... Additional sensors can be carried by blue forces as they enter the structure to verify or refine the interior situational awareness and improve our forces manoeuverability.

Specifically, the war-nerds think that operational systems would be deployed in vehicles and aircraft, or perhaps placed near a building of interest by US personnel. The latter static jobs should be no bigger than backpack sized, and "compatible with clandestine operations".

The combined suite of equipment should be able to produce complete floorplans of a ten storey building plus two-storey basement, with walls and stairwells located to within 1m. Any hidden tunnels should be identified, and any access to connecting buildings. The scanners should be able to see through concrete structural walls complete with rebar, and yet still detect internal stud-wall partitions.

All this should be achieved without any US personnel needing to get within 10m of the building, and only brief excursions inside 20m: and the machinery should have the complete building map produced within 3 days.

And don't be coming to DARPA with any "external through-the-wall radar solutions" as these are already being handled under another programme.

Just how the miracle-mapper gear should work is up to the proposer. However DARPA seem to be hinting at clever kit of some kind hooked up outside the building to water mains, power lines, sewer connections, or the ground in which it stands.

DARPA asserts that: • Stimulus response of building infrastructure contains tactically useful information on the interior structure. Infrastructure includes, but is not limited to, the structural, electrical, plumbing, and ventilation systems. • Such information may be acquired through access to the exterior of buildings that may include direct contact with an exterior umbilical, but does not require contact or deployments within the building. • Approaches to acquiring such information may require active as well as passive sensing.

So roughly speaking it looks as though mysterious echoes or signals sent through wiring, plumbing and building structure are expected to do the job. After three days of clandestine-ops imagery has been gathered on a building of interest, a complete 3D interior map will be generated.

Which should mean that when the black-clad assault team blows in the doors, there will be much less chance of embarrassing blunders such as getting lost, charging violently into cupboards etc - and much less chance of the building's denizens escaping through their prepared bolthole into next door's basement.

Americans will no doubt find it reassuring that this technology is only to be used "overseas". Definitely.

More details from DARPA in pdf here. ®