The tools for safely disposing of explosive threats like improvised explosive devices (IEDs) have come a long way over the last decade, but one rule of explosives ordnance disposal (EOD) holds fast regardless of how much technology you throw at it: you can’t terminate a threat if you don’t know where it is. To that end, the Office of Naval Research is hoping to field a new sensor package that can see bombs buried under the ground or otherwise obscured from view by blasting them with sound waves and seeing what kinds of vibrations come back.

The imperfectly acronymed GREMLIN (for Ground-Based Explosive Ordinance Disposal Mobile Laser Interrogation) is an augmentation for ground robots already employed by EOD units in places like Afghanistan that would--if all goes to plan--allow EOD operators to see beneath the ground before they start digging around looking for a suspected IED. Defense contractor BAE Systems already has $2 million in Navy cash on hand to help it look into possible GREMLIN technologies.