Northrop Grumman has successfully flight-tested a new quantum navigation system aboard its Lumberjack drone. By taking ultra-precise measurements of Earth's magnetic field, the system allows the aircraft to calculate its course and position without relying on satellite navigation.
Drones are far more than just jumped-up model planes. Operating them isn't merely a matter of shrinking standard flight systems down into a smaller airframe or designing around the absence of a cockpit. Many other things have to be included, like advanced sensors, autonomous software, onboard computers, and data links.
For military drones, a reliable navigation system is essential because combat and reconnaissance drones must be able to reach their targets with absolute precision.
However, satellite-based navigation systems like GPS and GNSS are vulnerable. In high-threat environments, opponents can jam or spoof satellite signals to disorient autonomous platforms. Signal loss can also occur naturally in deep canyons, dense urban areas, or near polar regions where satellite geometry and atmospheric interference degrade accuracy.
There are a number of ways to find your way if GPS is jammed, spoofed, or just isn't there. The one that Northrop Grumman and artificial intelligence and quantum tech firm SandboxAQ have developed is similar to a trick that's used by sailors.
Traditionally, sailors in dense fog could determine their position without a compass by using depth sounders to match seabed depth contours against known bathymetric charts and tide tables. If you know your original position and can do a bit of dead reckoning, it's a pretty easy technique.
What Northrop Grumman's system does is essentially the same thing, except in three dimensions. It measures minute variations in the magnetic field, including strength, variance from magnetic north, and dip, that have been mapped in an extensive database and, through the use of an AI Large Quantitative model, the patterns measured can be matched to the database, providing a precise location in real time.
The key to SandboxAQ's AQNav system that was installed aboard a Lumberjack drone is an Optically Pumped Magnetometer (OPM). Without going into mind-numbing technical detail, the OPM consists of a small glass vapor cell containing alkali atoms such as rubidium, cesium, or potassium. These atoms are illuminated with a special polarized laser tuned to a specific frequency. When the laser beam hits the atoms, this causes them to align in a particular direction. An external magnetic field, such as that produced by the Earth, will cause these aligned atoms to wobble. Measuring this wobble and doing some complicated sums gives the exact strength and orientation of the field to as low as 10⁻¹⁵ Teslas.
That may all sound clever enough, but the beauty of the system is that it can operate at room temperature, so no need to take complex cooling system or bottles of liquid helium along for the ride, which is nice when it has to fit inside a Lumberjack that itself has an empty weight of 79 lb (36 kg) and a maximum gross takeoff weight of approximately 290 lb (131 kg).
According to Northrop Grumman, the navigation system cannot be jammed or spoofed because it relies entirely on passive, naturally occurring planetary magnetic fields, not an external signal. In addition, the recent flight tests demonstrated that the quantum navigator can work alongside a visual navigation system and that its modular design allowed the whole thing achieve operational flight testing less than a month after the fly the system in such a drone platform.
The cost of the Lumberjack airframe is estimated at between US$75,000 and $100,000 per unit, so adding this kind of software-centric quantum navigation gives these (relatively) low-cost drones a huge boost in reliability without driving the price tag out of reach.
"Lumberjack showcases not only ‘best-of-breed’ technology across industries, but our ability to integrate quickly has moved us from vision to operational reality in a rapid timeline," said Max Schuster, program manager, Lumberjack, Northrop Grumman. "Adding quantum sensing to an adaptable autonomous platform like Lumberjack advances mission capability in GPS-denied environments."
Source: Northrop Grumman
