Air Force tunes up quantum navigation for a fight without GPS

Flying across the world with modern GPS is not much harder than using a navigation app in your car, which is why most military planners expect the global satellite system to be knocked out early in any major future conflict.

To prepare for a no-GPS sky, a Pentagon test flight last month over Alaska made a major leap toward how the U.S. military plans to fly to and from targets without the satellite system, overseen by the Pentagon’s newest technology unit.

Flying a modified Embraer 170 over the Pacific Ocean, the test crew flew from Seattle, Washington, to southern Alaska and back — a four-hour flight — navigating with quantum sensors that read a sensitive magnetic map of the Earth not used in any other navigation technology.

The test was overseen by the Pentagon’s Defense Innovation Unit, an office aimed at getting new technology into military use. Though the Embraer 170 was a specially modified civilian plane, the Air Force plans to test the technology on a C-17 later this year, the Pentagon said.

The system works like this: the crust of the Earth is not a smooth billiard ball of even rock, but is rather a patchwork of large deposits of different minerals and elements. For instance, coal mining or oil exploration occurs where large deposits of coal and petroleum are available for their mines and wells. Mountain ranges are often made of granite, while vast veins of iron ore sit in the Canadian north.

Each element has a distinct magnetic signature, as obvious to a magnetic sensor on a plane overhead as a forest or desert would be to the eye of a pilot.

Dubbed Magnetic Anomaly Aided Navigation, or MagNav, and developed by Honeywell, the system uses a highly tuned map of the magnetic signatures of all the deposits of various elements around the Earth’s crust to navigate over.

Unlike GPS or other man-made magnetic-based navigation, the magnetic fields produced by the geological formations in the Earth can’t be spoofed or blocked by technology, are impervious to weather, and their locations do not move.

The August flight used the map to fly over open ocean.

“After four hours and 23 minutes of flying over the ocean without GPS, the MagNav system improved position accuracy by 89% compared to traditional backup navigation methods,” the Pentagon said in a news release on the flight.

Though simple in concept — a map of rock in the earth — the technology is particularly cutting-edge. As any service member who has been through a land-navigation course can vouch, the earth has one magnetic field far larger than any other. The pull of magnetic north — which a handheld compass tracks — makes up more than 99% of all magnetic signals.

Reading the magnetic map requires an onboard system that can filter out both the Earth’s field and adjust the instruments to ignore the magnetic signals produced by the plane itself.

To do that, researchers used quantum sensors, which track magnetic fields by their effect on subatomic particles.