Pentagon Doubling Down on Alternatives to GPS That Aren’t in Space

The U.S. military is doubling down on non-space-based alternatives to GPS, the ubiquitous position, navigation, and timing service provided by the U.S. Space Force, with new funding for the development and testing of operational prototypes of quantum-based devices that don’t depend on easily jammable signals from satellites. 

Last month the Pentagon’s cutting-edge technology research arm, the Defense Advanced Research Projects Agency announced the start of Phase 1 of its Robust Quantum Sensors, or RoQS, program, a trailblazing effort to prototype quantum sensing technology to provide a localized, non-space-based alternative to GPS. Although DARPA has not released any spending figures for RoQS, one company selected for the program said it received two contracts totaling $24.4M. 

“If we’re relying on space-based, GPS-based PNT, then we may be in trouble,” Vice Chairman of the Joint Chiefs of Staff Adm. Christopher W. Grady told industry executives last week at a National Defense Industrial Association conference in Washington, D.C. Explaining that despite recent improvements, GPS signals remained susceptible to jamming, Grady said developing alternative PNT sources was “a passion project,” for him, and something that “I am extremely focused on to enable the warfighting team to go do their job.” 

Grady’s observations got some real-world emphasis over the weekend when GPS jamming, allegedly by Russia, forced the plane carrying EU Commission President Ursula von der Leyen to land using paper maps and ground-based navigational signals, according to the BBC, although there’s some confusion among experts owing to contradictory technical data. The Bulgarian government has ordered an inquiry. 

The visit, to Bulgaria, was part of a tour by von der Leyen of EU nations on the front line between the bloc and Russia. 

It’s just the latest in a string of incidents that demonstrate Russia’s ability to jam GPS, something it has done so frequently since the start of the Ukraine war that commercial airline pilots in the Baltic states now must routinely rely on alternative navigation systems.  

The risks created by GPS’ fragility for U.S. warfighters—and for the broader world economy, where sectors like finance and transportation have become completely dependent on GPS—are well understood, and several innovation-focused organizations in the DOD have programs that are seeking to develop alternatives. 

In addition to DARPA’s RoQS program, the Defense Innovation Unit, the Pentagon’s outpost in Silicon Valley, launched a Transition of Quantum Sensors program last year. Like DARPA, DIU is focused on getting quantum PNT equipment out of the laboratory and onto the battlefield. 

The focus on quantum is not a coincidence, said Grady, calling it one of the most promising approaches to a resilient alternative PNT. One that would allow warfighters “to fight through those [electromagnetic warfare] saturated environments that we’re seeing like in Ukraine right now.” 

A report in June from the Lawrence Livermore National Laboratory identified three quantum sensing-powered technologies as being promising for alternative PNT. Inertial navigation works by tracking where and how fast a vehicle is moving and applying that to a known location where it was. Typically inertial devices “drift,” meaning their estimate of their location becomes less accurate over time, and must be re-baselined with a new, currently accurate location at regular intervals. Because quantum sensors are orders of magnitude more sensitive than their conventional counterparts, it is in theory possible to build an inertial location device that doesn’t need recalibrating and can maintain its accuracy independently. 

The latest flight of the secretive X-37B space plane in August carried a quantum inertial sensor, the Space Force has said. 

The other two quantum-based approaches identified in the Lawrence Livermore report use tiny variations in the earth’s magnetic field or in its gravitational field. Measuring gravitational or magnetic fields in one place, and then comparing that to detailed maps of the earth’s fields has been called quantum orienteering, because of its resemblance to map-based location techniques using physical landmarks.  

All three approaches can provide localized alternative PNT data, independent of GPS or any other space-based signal, the report said. Quantum sensing alternate PNT methods, the author notes, “would be internal to their vehicle and are therefore immune to EW tactics and space-based attacks.” 

However, the report notes that, while these technologies have been validated under laboratory conditions, making a device that will work in the noisy, vibration filled interior of an aircraft, for example, is a very different matter.  

Participants in DARPA’s RoQS program will build a prototype “walk-on/walk-off” device that can be taken on board a helicopter for long flights, testing its performance under real-world conditions.  

Q-CRTL, an Australia-based startup which is one of the first awardees under the program, uses software algorithms to account for and eliminate interference. DARPA gave Q-CTRL two contracts, one in partnership with defense giant Lockheed Martin, for a total of $24.4 million, the company said last week.  

Michael Biercuk, Q-CTRL’s CEO and founder, said in a statement they were “excited” to start work with DARPA, to “deliver a new generation of software-ruggedized quantum sensors for the most challenging defense missions.” 

This story has been updated to reflect uncertainty about the jamming of GPS on von der Leyen’s plane.