Scientists test new (and old) navigation systems to end GPS dependence

On a UK military test flight over southern England in May 2024, a team of British and American physicists carried a briefcase-sized object containing one of the strangest substances in the universe: a cloud of atoms cooled so close to absolute zero temperature that they merged into a single quantum state.

Known as a Bose-Einstein condensate, it is a new form of matter first created in a laboratory in 1995. The experiment, carried out by BAE Systems, Infleqtion, a Colorado-based tech company, and UK-based defence company QinetiQ, marked the first time such an object is known to have survived intact aboard an aircraft in flight. Defence companies such as BAE believe it could help solve one of modern warfare’s most pressing problems: how to navigate when GPS disappears.

The race to build alternatives to satellite navigation has accelerated as Russia’s war in Ukraine and conflict in the Middle East have demonstrated how vulnerable GPS has become to jamming, spoofing and other disruptions.

Rather than assuming satellite signals will always be available, the world’s militaries are now designing aircraft, drones and missiles that can find their way using entirely different methods. These range from revived cold war radio beacons to quantum sensors that can, as whales and some birds are thought to do, navigate by using the Earth’s magnetic field.

GPS, widely used since the turn of the century, triangulates satellite signals to provide precise location, time and velocity for crucial services such as aviation, shipping, road transport, telecommunications, electricity grids and financial markets.

Alan Woodward — a visiting professor at the University of Surrey who worked for UK government intelligence during the cold war and now specialises in systems security — says the main problem with navigation systems using satellites is that they are controlled either by a particular government or by a “tech bro”.

“You have got to have fallbacks,” he says. “That’s why a lot of this research has been quietly going on in the background.”

The risk posed by GPS interference is “very significant” for critical national infrastructure, the economy and national security, says Malcolm Macdonald, a signal processing and space technology expert at the University of Strathclyde.

“This is what we already see in eastern Europe and the Middle East where jamming is a regular day-to-day occurrence,” Macdonald says. “This then further extends into the battlefield where GPS is typically unavailable.”

Among the most high-tech (and most expensive) potential solutions is the one developed by Infleqtion, a Colorado-based quantum technology company whose experimental technology was aboard the flight over England.

By using lasers to hold atoms almost perfectly motionless — at a temperature of a few billionths of a degree above absolute zero, even though the casing of the device remains at room temperature — the technology creates a quantum sensor.

This is capable of detecting minute movements with far greater precision than conventional inertial navigation systems, such as the laser ring gyroscopes used by advanced aircraft and cruise missiles. (Inertial navigation measures the movement of an object from its starting point using sensors such as accelerometers and gyroscopes and does not rely on outside signals.)

Unlike GPS, which depends on triangulating precisely timed radio signals received from satellites, it cannot be jammed because it is self-contained.

Matthew Kinsella, Infleqtion’s chief executive, said the material is orders of magnitude more precise than the current state of the art in inertial navigation. “Crucially, it does not drift,” he said.

At about $1mn per unit, the likely cost is for the moment prohibitive except for valuable submarines, ships and aircraft. “It’s not something you would put on a single-use drone,” says Kinsella.

The assumption that GPS would always be available has quietly become one of the first casualties of modern electronic warfare. Due to electronic jamming, many previously fearsome GPS-guided weapons, such as Himars rocket artillery and Excalibur guided artillery, have ceased to be accurate in Ukraine.

But the problem is no longer confined to war zones. About 40 per cent of European air traffic is now affected by interference with GPS, according to European aviation authorities, with evidence pointing to Russia’s heavily militarised Kaliningrad exclave and the Kola Peninsula as major sources of disruption.

Commercial airliners — particularly in the eastern Mediterranean near Israel, or in the Black Sea near Ukraine — have reported losing GPS signals or receiving false position data, forcing pilots to revert to traditional inertial navigation sensors.

Another possible high-tech solution comes from Canadian start-up SBQuantum, based in Quebec, which is developing quantum magnetometers that navigate by reading subtle variations in the Earth’s magnetic field. The approach is similar to one of the methods scientists believe is used by whales, sea turtles and migratory birds to navigate across oceans.

“Nature has mastered magnetic navigation to some extent,” said David Roy-Guay, founder and chief technology officer of SBQuantum. “We’re kind of catching up there.”

The company’s “Zero Drift Navigator” is designed to work alongside an aircraft’s inertial navigation system, periodically correcting the gradual errors that accumulate once GPS signals are lost. Unlike GPS, the characteristics and anomalies in Earth’s magnetic field cannot easily be jammed or spoofed.

The trade-off is accuracy. Magnetic navigation generally requires detailed maps of the Earth’s magnetic landscape and currently offers precision measured in tens or hundreds of metres rather than the metres or centimetres provided by GPS.

SBQuantum says its first-generation system is targeting accuracy of about 100 metres throughout an entire flight and is expected to cost about $25,000. That is cheap enough for large drones, aircraft and autonomous underwater vehicles, though not yet for expendable munitions, nor is it accurate enough for missiles or shells.

Other companies are developing vision-based systems that allow drones and missiles to compare live camera images with stored satellite imagery, technology once available only for the most advanced cruise missiles that is now cheap enough to use on drones.

The use of multiple navigation systems that can take over from each other when one of them is blocked is also on the agenda. Rather than betting on a single solution, defence planners are increasingly building redundancy into the next generation of weapons.

“For me, the most resilient system is one that merges multiple techniques rather than relies only on one of them,” Macdonald says.

Modern cruise missiles such as the latest Tomahawk combine GPS with inertial navigation, terrain contour matching and optical scene-matching, ensuring that if one method is denied another can take over.

German-American drone software company Auterion markets technology for battlefield drones that combines satellite signals with inertial sensors and a downward-facing camera that continuously compares live video of the terrain below with digital maps. The company says the entire package adds only “low tens of thousands” of dollars to the cost of a drone, though the mapping does not work well over water or featureless terrain.

Another such combination of sensors was trialled on Sept 9, when Sandbox AQ, a spin off from Alphabet Inc, demonstrated a quantum-sensing magnetic navigation device paired with a visual navigation system on a one-way attack drone made by Northrop Grumman.

The potential disruption to satellite-based navigation has also triggered the re-emergence of pre-GPS techniques — what Woodward calls “the old ways” — that use ground-based infrastructure.

The UK, for example, is building ground-based transmitters and receivers known as enhanced long-range navigation (eLoran), based on the Loran system first deployed during the second world war and later used by shipping until the rise of GPS. In May, the UK government announced it had awarded a £6mn contract to develop eLoran to a partnership led by QinetiQ.

A significant advantage of eLoran is that spoofing or jamming it requires large, high-powered transmitters, meaning potential attacks should be easy to spot and so more preventable.

Another option is to stop relying on GPS signals emitted from satellites in geostationary orbits 20,000km above Earth and use other satellites instead.

Todd Humphreys, director of the Radionavigation Laboratory at the University of Texas at Austin, said different satellite constellations in lower orbits may provide more robust signals that are harder to jam. Companies operating such satellites include telecoms company Iridium and Elon Musk’s internet data company Starlink, both of which offer navigation services.

“There is no silver bullet,” said Humphreys of the search for alternatives to GPS, “but several bronze bullets have emerged.”