Between 2019 and 2026, ground-based GNSS monitoring stations recorded 75 events of simultaneous signal blackout across Europe, from Spain and Romania to Greenland. No ground-based jammer could cover that distance. Researchers at the University of Texas at Austin eventually traced the source to a single satellite in orbit over 1,200 kilometres above Earth: Cosmos 2546
Here is what the research found, and what it means for any operation that depends on GNSS, including UAV operations.
What is GPS Jamming
Before looking at the investigation, it is worth understanding what type of interference this was, because not all GNSS disruptions work the same way.
Spoofing involves transmitting counterfeit GNSS signals that mimic real satellites, a receiver is fed false position data without realising it. The system appears to work normally, but the location it reports is wrong.
Jamming is different. A jammer broadcasts high-powered radio noise across the frequency bands used by GNSS constellations, overwhelming legitimate signals until the receiver’s signal-to-noise ratio drops below the threshold required to track and decode them. The receiver simply loses lock and it stops working entirely.
What Cosmos 2546 appears to produce is broadband noise jamming, transmitted from orbit. The interference was documented at 1,558.5 MHz, within the L1 band used by both GPS and Europe’s Galileo system, and a second burst was detected at a lower frequency overlapping with China’s BeiDou constellation. Crucially, the signal was not centred precisely on the GPS frequency but slightly offset from it, close enough to disrupt reception, but not directly on target.
Unlike ground-based jammers, typically small, cheap devices with a range of a few kilometres, a space-based jammer operating from Molniya orbit can maintain line of sight over a continental-scale footprint simultaneously. That is what makes this case technically significant: the geometry of the disruption is physically impossible to replicate from the ground or from aircraft.
75 events in 7 Years
The monitoring data comes from the International GNSS Service (IGS), a global network of tracking stations that continuously records GNSS signal quality. From January 2019 to April 2026, researchers at the University of Texas identified 75 disruption events sharing the same signature: a sudden, total drop in signal strength, lasting between three and ten seconds, occurring simultaneously at receivers thousands of kilometres apart.
The disruptions were too uniform to be solar radio bursts, which affect signal quality unevenly and correlate with solar activity. And the affected area spanning from the Iberian Peninsula across Central Europe to Greenland was far beyond the reach of any ground-based or airborne transmitter. Calculating the minimum source altitude from the geometry of the signal’s impact across the receiver network pointed to at least 1,200 kilometres above Earth’s surface.
One further detail stood out in the data: the events were concentrated on Tuesdays, Wednesdays, and Thursdays, during standard business hours.
How researchers found the source
The investigation was led by Professor Todd Humphreys and researcher Zach Clements at the UT Austin Radionavigation Laboratory. Their approach used the signal arrival-time differences between geographically spread receivers to triangulate the source, a method similar in principle to how GNSS itself calculates position but in reverse.
The search space was large. Around 15,000 satellites and tracked objects orbit at relevant altitudes. Progress came when the team obtained raw baseband recordings from stations in Amsterdam and Trondheim, which allowed timing measurements precise enough to narrow the candidate list to a single orbital track. Independent verification was provided by GMV, a Spanish aerospace company that operates GNSS interference monitoring infrastructure.
The orbit of one satellite matched every recorded event without exception.
Cosmos 2546 and the EKS Constellation
The satellite is Cosmos 2546, launched by Russia in May 2020. It is part of the Edinaya Kosmicheskaya Sistema (EKS), Russia’s constellation of military early-warning satellites used to detect ballistic missile launches. The EKS satellites fly in Molniya orbits, highly elliptical trajectories designed to maximise time above high northern latitudes. That same geometry provides sustained, direct line of sight over large parts of Europe and the North Atlantic.
The research findings were published in Navigation, the journal of the Institute of Navigation. The paper was submitted for peer review at publication. Victoria Samson, chief director of space security and stability at the Secure World Foundation, commented on the findings: “It does appear to be a space-based jammer.”
The researchers make no specific claims about intent. The documented pattern, brief, periodic, offset from the exact GPS frequency, is what the data shows. The paper presents it as a documented technical phenomenon and identifies the probable source. What the pattern means operationally for those who depend on GNSS is a separate question.
What this means for Drone Operations
The 75 events over seven years represent what was detectable using available monitoring infrastructure. Individual outages of three to ten seconds may seem negligible. In isolation, they are but they reveal a structural condition that matters for mission design.
GNSS underpins nearly every aspect of commercial drone operations: positioning accuracy, flight path repeatability, safe return-to-home behaviour, and the georeferencing that makes inspection data usable. These functions are typically treated as reliable by default. The architecture of most commercial drone platforms is built around continuous GNSS availability. When that availability fails, whether from a technical fault, local interference, or a space-based source, the degree of operational resilience depends entirely on what alternative systems the platform carries.
One approach to that problem is True North, a navigation module developed to remove the GNSS dependency at the hardware level. Rather than supplementing satellite positioning with a backup, True North replaces it as the primary positioning reference. The module uses inertial measurement, sensor fusion, and onboard processing to determine and maintain position independently of any external signal including satellite navigation. It operates the same way whether GNSS is fully available, degraded, or absent entirely. For inspection platforms operating in environments where signal reliability cannot be guaranteed, that distinction matters: the mission continues under conditions that would otherwise cause a standard platform to abort or behave unpredictably.
Aviation, maritime navigation, precision agriculture, energy grid timing, and telecommunications infrastructure share the same dependency. The disruptions documented by Humphreys and Clements were short and infrequent. The research does not change day-to-day operational reality. What it changes is the factual basis on which GNSS can be assumed to be available under all conditions.
Designing for GNSS Resilience
The answer to satellite navigation vulnerability is not to abandon GNSS. It remains the most accurate, globally available positioning reference available for civil and commercial use. The answer is to design operations and systems that do not treat it as the sole and unconditional foundation.
The scenario described in this research, satellite navigation unavailable across a continental footprint, with no ground-based countermeasure is the operational condition True North was built for. The module replaces GNSS as the positioning reference, using alternative sensing methods that function regardless of signal environment.
Inertial navigation, visual odometry, terrain-referenced navigation, and sensor fusion approaches can all contribute to maintaining position awareness when GNSS signals are degraded or lost. The maturity and cost of these technologies has changed significantly in recent years. What once required military-grade hardware is increasingly accessible to commercial platforms.
The research from Humphreys and Clements puts documented evidence behind a risk that serious operators have been building against for some time. It is a reason to know, precisely, what your system does in the seconds after GNSS lock is gone.
The research paper — “Chasing Lightning: Detecting, Characterizing, and Identifying a Powerful Space-Based GNSS Interference Source” by Clements, Kriezis, and Humphreys — is published in the journal Navigation and was the subject of a Veritasium documentary released in June 2026.
