Seeing through the Earth's crust, clearlyUnderground intelligence satellite navigation will work off lightning strikes

“Run silent, run deep,” is an old submariner term. Soon, however, it may apply to ground forces as well. It appears that the U.S. military has a secretive program intended to let troops navigate about inside huge underground enemy tunnel complexes by measuring energy pulses given off by lightning bolts.

Lewis Page writes that the project is known as Sferics-Based Underground Geolocation,, or S-BUG, and is focused on building “a mapping and navigation system that provides Global Positioning System (GPS) equivalent accuracy in underground environments” (see “The Last Frontier: DARPA Wants to Make the Earth’s Crust Transparent,” 10 March 2010 HSNW; and “Geospatial Corporation Maps the World under the Earth’s Crust,” 10 March 2010 HSNW).

GPS signals from U.S. military satellites are used in millions of smartphones, car satellite navigation, and other gadgets worldwide, but they do not work without clear line-of-sight to the satellites — that is, without an unobstructed view of the sky.

Page notes that the U.S. ubiquitous eye-in-the-sky satellites have driven more and more people and things of interest to disappear underground. The U.S. intelligence community is no doubt aware that tunneling and subterranean engineering in general have become much cheaper in recent times, making this easier to do (see, for example, William J. Broad, “Iran Shielding Its Nuclear Efforts in Maze of Tunnels,” 5 January 2010 New York Times).

Deep tunnel complex shield an organization from the prying eyes of satellites, and it is also good protection against a sudden bombing raid of the sort which destroyed Iraq’s Osirak reactor in 1981 and the nuclear facility in Syria during 2007.

This move underground for concealment and protection has brought the U.S. intelligence and special operations communities to seek the means for subterranean intelligence gathering and operations.

Page writes: “Naturally, when wondering how to navigate deep below the Earth’s surface in a hollowed-out lair where a secret superweapon is being fashioned for the purpose of holding the world to ransom, there’s only one federal agency to call: DARPA” (this is the place, Page says, where they “believe it is better to invent a head-mounted multispectral imaging device than curse the darkness”).

DARPA researchers have noted that one of the few kinds of wireless signal which can penetrate underground is low-frequency radio. “Such signals, however, are not easy to generate at the required power levels. A network of low-frequency RF navigation stations widespread enough to offer decent accuracy would probably be impossible to deploy,” Page writes.

The right kind of signals are generated naturally by lightning strikes, which cause the emission of “atmospheric” (“sferic” or “spheric”) radio pulses. An underground receiver could perhaps be built capable of detecting sferics from lightning bolts hitting the surface hundreds of miles away. It could be informed of the positions of the strikes over LF communications by a single specialized surface base station, similarly far off, and thus calculate its own position from sferic data coming in from several directions.

Hence S-BUG, which was reportedly the subject of a small DARPA feasibility investigation last year. Evidently this indicated that S-BUG might just possibly be feasible, as the agency is now to hold a conference (mostly classified SECRET) for tech firms interested in taking the project forward. Page notes that, coincidence or not, DARPA has lately started up another project, NIMBUS, aimed at triggering artificial lightning (see “DARPA Scientists Seeking Lightning on Tap,” 22 December 2009 HSNW