Phillips Laboratory aimed to use 960 kilowatts to image secret bunkers
By Marcus Boone ·
Adversaries faced a covert effort to turn the earth into a transparent medium, allowing the military to image hidden tunnels and bunkers without their knowledge.
The Space Effects Division of the Phillips Laboratory Geophysics Directorate wanted a way to see through the earth. According to a document mirrored by the FAS Intelligence Resource Program, the goal was to "detect and image subterranean features such as tunnels, bunkers, and other potential military targets."
This was not a request for a map of existing mines or a survey of geological strata for the sake of science. It was a call for "original and innovative research" into the viability of using electromagnetic induction to strip away the cover of the soil. The document, a PRDA issued on June 2, 1997, outlines a technical ambition to turn the ground itself into a transparent medium, allowing the military to identify "man-made structures or natural voids" hiding beneath the surface.
Tunnels, Bunkers, and Other Potential Military Targets
The technical logic relies on Extremely Low Frequency (ELF) and Very Low Frequency (VLF) radio waves. These waves, the record explains, "penetrate deeply beneath the surface of the earth and interact with the geologic structure." This interaction creates secondary fields that can be measured from the surface. While the document admits that using natural sources like lightning or auroras is an established procedure for finding metal ore deposits, the Phillips Laboratory was interested in something more precise and more aggressive.
To move from ore-hunting to target-hunting, the government needed to solve six primary problems. These included the physics of wave generation, the effects of surface topography, and the development of algorithms to produce "unambiguous detection and classification" of structures. The intent was to separate the signal of a concrete bunker or a reinforced tunnel from the "geological noise and clutter" of the natural world. It is a classic surveillance problem: how to isolate a specific, hidden human presence from the chaos of the environment.
Document imagery from irp.fas.org From the files: irp.fas.org
Covert Measurement
One of the most telling requirements in the PRDA is the insistence on secrecy. The Phillips Laboratory did not just want to measure these waves; they wanted "methods for measuring ELF/VLF field components in a covert manner."
This requirement shifts the project from a theoretical geophysical exercise into the realm of operational intelligence. The focus on covert measurement suggests a scenario where these imaging techniques would be deployed in contested or foreign territory, where the presence of the sensors could not be detected by the party whose bunkers were being imaged. The government was not merely interested in the physics of the ionosphere or the crust; it was interested in the ability to peer into the hidden depths of an adversary without their knowledge.
Gakona and Fairbanks
To power this effort, the military looked to the far north. Proposers were encouraged to use the "controlled ELF/VLF sources" provided by two specific facilities: the HIPAS facility near Fairbanks, Alaska, and the 960KW HF transmitter of the High-frequency Active Auroral Research Program (HAARP) outside Gakona.
Public records, including Wikipedia, establish that HAARP was initially a joint venture funded by the U.S. Air Force, the U.S. Navy, DARPA, and the University of Alaska Fairbanks, designed to investigate ionospheric enhancement for radio communications and surveillance. The FAS mirror confirms that by 1997, the HAARP facility was "presently under construction" and managed by the PL/GPS program.
The scale of the Gakona transmitter—nearly a megawatt of power—provided the raw energy necessary to excite the atmosphere and, by extension, create the signals needed to probe the subsurface. By leveraging the HAARP transmitter, the Phillips Laboratory hoped to move beyond the unpredictability of lightning strikes and create a controlled, artificial signal that could be used to map the underground.
June 2, 1997
The PRDA demanded that any successful proposer demonstrate a basic understanding of "ELF/VLF guided-wave propagation" and the ability to invert data into "depth-dependent geophysical models." The objective was a clear, actionable image of a target hidden under layers of rock and dirt.
While the technical details of whether the Phillips Laboratory ever achieved "unambiguous detection" of subterranean bunkers remain absent from this specific record, the diplomatic fallout of such capabilities is noted. The FAS mirror includes a reference to an August 8, 2002, Interfax report stating that the Russian Parliament had expressed concern about the HAARP facility.
The document is identified as SOL PRDA PL/GPS 97-02 CBD.