Amateur Astronomer Finds U.S. Government-Operated Starshield Satellites Broadcasting on Unauthorized Frequencies

An amateur astronomer has uncovered a series of unusual radio transmissions that appear to come from SpaceX’s classified Starshield satellites and are being broadcast on frequencies normally reserved for uplinks. The discovery raises questions about spectrum management, potential interference with nearby spacecraft, and how classified satellite programs operate within international radio rules.

How the signals were found

Scott Tilley, a Canadian amateur astronomer known for tracking elusive objects in orbit, says he stumbled onto the signals by accident after switching his receiver to an uncommon frequency band. After comparing his recordings with other hobbyist observers, he concluded the transmissions likely originate from Starshield satellites. Tilley’s analysis was published in a paper on Oct. 17; it has not yet been peer-reviewed.

What the signals show

The transmissions occupy the 2,025–2,110 MHz range. Under typical allocations, that band is set aside for uplinks — signals sent from ground stations up to spacecraft — while downlinks (satellite-to-ground transmissions) are assigned different bands by the International Telecommunication Union (ITU), the UN body that coordinates global radio-spectrum use. In this case, the satellites appear to be sending downlink traffic on an uplink band, meaning the emissions fall outside the usual downlink allocations.

"It was just a clumsy move at the keyboard," Tilley said of his initial discovery. "I was resetting some stuff and then all of a sudden I'm looking at the wrong antenna, the wrong band."

Scale and possible intent

Tilley reports detecting signals from roughly 170 distinct Starshield satellites, which suggests the behavior could be widespread across the Starshield constellation rather than an isolated anomaly. Starshield is a government-focused offshoot of the commercial Starlink network that supplies specialized satellites to U.S. agencies, including the National Reconnaissance Office (NRO) and the U.S. Space Force. Public information about Starshield’s mission parameters, orbital placements and technical design remains limited.

Potential impacts and expert perspectives

Experts warn that satellites transmitting on unexpected frequencies could create radio-frequency interference for nearby spacecraft. That interference could, in principle, make it harder for those satellites to receive commands from ground controllers — or cause them to misinterpret or ignore instructions. However, no operational incidents have been publicly linked to these transmissions so far.

Benjamin Winkel, a radio astronomer at the Max Planck Institute for Radio Astronomy, says the emissions "seem to be intentionally emitted by Starshield satellites, but outside of permitted frequency ranges," while Kevin Gifford, a researcher who studies radio interference from spacecraft, says the phenomenon is "definitely happening" but cautions that evidence of real-world harm is not yet available.

Context: unintended emissions and growing congestion

The discovery follows previous findings that earlier-generation Starlink satellites leak unintended electromagnetic radiation (UEMR) into radio bands used by astronomers. Studies have shown Generation 1 Starlinks produced measurable leakage, and later-generation satellites have exhibited similar or larger effects. As commercial constellations expand, concerns about spectrum pollution and its impact on radio astronomy and on satellite operations have intensified.

SpaceX has launched many thousands of Starlink satellites; active Starlink vehicles now constitute a large share of the world’s operational satellite fleet. Estimates put Starshield deployments in the low hundreds, and government contracts for the program have been reported to total in the billions of dollars. Neither SpaceX nor the NRO has publicly commented on the newly reported signals.

What comes next

Key questions remain: why the satellites are using uplink bands for downlink traffic, whether the emissions are an intentional operational choice, and whether regulators or operators will alter practices in response. The episode underscores the growing challenge of managing radio spectrum in an increasingly crowded near-Earth environment and the need for clear coordination between commercial operators, government users and international regulators to avoid interference.

Note: Tilley’s paper and the initial detections have not yet been peer-reviewed. Independent verification and further study will be required to confirm the details of the transmissions and any operational impacts.