Russian Satellites Scramble Europe’s GPS

The GPS signal that tells your phone where it is arrives almost as a whisper. After travelling 20,000 km from orbit, it reaches Earth weaker than the thermal noise of stars and sunlight. Your receiver makes sense of it because it knows exactly what to listen for. Put a louder signal on almost the same frequency, and the whisper is gone.

Across Europe, from Iceland to Italy, that has happened at least 75 times since 2019. The source appears to be a group of Russian military satellites orbiting as high as 45,000 km above Earth.

Pinpointing a Satellite by Its Shadow

Researchers at the University of Texas, led by Prof. Todd Humphreys and student Zachary Clements, tracked sudden falls in GPS signal quality recorded by monitoring stations across Europe. Each time, the navigation signal collapsed by roughly a factor of ten, across receivers thousands of kilometres apart. A jammer on the ground, constrained by the curve of the Earth, could not create that pattern.

The source was traced to Russia's Tundra satellites, part of the EKS/Kupol early-warning system built to detect ballistic missile launches. These spacecraft move in highly elliptical orbits, hanging for hours near their highest point while looking down over the Arctic and northern Europe. Their job is to watch for rocket plumes. But their downlink transmissions to Earth operate at 1,577.5 MHz, just 2.5 MHz from the GPS L1 frequency at 1,575 MHz. With a powerful transmitter that close, energy leaks into the GPS band in the way a loud radio station can bleed into the next channel.

The team confirmed the source using time-difference-of-arrival, a kind of reverse triangulation. They measured the tiny gap, in microseconds, between an interference burst reaching two distant stations, Amsterdam and Trondheim, 1,500 km apart. That delay places the source somewhere on a shell-shaped surface in space. Add enough station pairs and the shells meet at one point. Only one satellite was there: Cosmos 2546, matching to within 200 metres. Spanish technology firm GMV independently corroborated the findings using similar methods.

A Frequency That Spares Only GLONASS

The interference disrupts GPS, the American system, Galileo, Europe's system, and China's BeiDou, but leaves Russia's own GLONASS system untouched. The downlink frequency seems to avoid self-disruption while affecting rival systems. Researchers cannot yet say whether that is deliberate design or a convenient engineering outcome. A US Air Force briefing acknowledged the interference but did not publicly assess intent.

Each disruption lasts less than ten seconds and lines up with a satellite pass. Most devices recover by falling back to their last known position. Aircraft face the sharper operational problem. Commercial planes do carry backups, including inertial navigation and ground-based radio beacons, but losing GPS adds to pilot workload and weakens the precision of modern approach procedures that rely on satellite positioning.

Europe's Defence Has a Blind Spot

Europe's main answer so far has been Galileo's OSNMA authentication system, live since July 2025. It allows receivers to check that a navigation message really comes from a Galileo satellite. That helps against spoofing, the fake signals broadcast from Kaliningrad's expanding network of 36 ground-based transmitters. It does not help against jamming. If a signal is drowned out by noise, there is nothing left to authenticate.

The larger weakness is detection. European security thinking has treated GPS interference mainly as a ground-based threat. Space-based interference has now moved from theory into evidence, and Europe has limited means of seeing it for itself. France is the only European country with orbital detection capability: its NESS nanosatellite, launched in 2023, carries instruments designed to characterise interference sources from orbit. Germany plans to launch its own monitoring satellites in autumn 2026. Until then, Europe is relying heavily on American academics and ground-station data to identify threats coming from 45,000 km overhead.

The longer-term answer is a European low-orbit navigation constellation called Céleste, designed to transmit stronger signals that are harder to jam. It will not be fully operational until the mid-2030s. For now, Europe knows that its navigation signals are being drowned out from space. It still lacks the ability to watch the source directly.