A team of radio astronomers in Australia has traced an unusually powerful burst of radio waves to an unexpected source: a long-dead NASA satellite that has been orbiting Earth silently since 1967. The discovery, made using the ASKAP radio telescope and announced in 2025, has reignited debates about how the proliferation of orbital debris is interfering with one of astronomy’s most sensitive observational windows.
An Unexpected Signal From a Silent Spacecraft
The signal, which lasted just 30 nanoseconds, was initially mistaken for a fast radio burst (FRB) — the kind of mysterious extragalactic flash that has puzzled astronomers for over a decade. But when researchers at Curtin University and the International Centre for Radio Astronomy Research (ICRAR) traced its origin, they were astonished to find it had come from inside our own backyard. The culprit was Relay 2, an experimental NASA communications satellite that ceased operations in 1967 after its onboard transponders failed.
Lead author Clancy James, an associate professor at Curtin University, explained that the team initially believed they had captured a near-Earth astrophysical event. “We were looking for fast radio bursts and found something far closer to home,” James told reporters during the announcement, noting that the team was able to pinpoint the signal’s location to within tens of meters. Details of the discovery were published through the International Centre for Radio Astronomy Research, which operates the ASKAP array in Western Australia.
What Could Have Caused the Burst?
Researchers have proposed two leading explanations for how a defunct satellite could suddenly emit such an intense pulse. The first is an electrostatic discharge — a build-up of charged particles on the spacecraft’s metal surface that, when released, produces a brief but powerful electromagnetic pulse. The second possibility is a micrometeoroid strike, in which a tiny high-velocity particle hit the satellite and generated a small plasma cloud capable of emitting radio waves.
Both explanations carry significant implications. If aging satellites can spontaneously discharge, scientists may have a new tool for monitoring the health of dormant spacecraft. The phenomenon could also serve as a previously unrecognized source of contamination in radio astronomy data, potentially mimicking the signatures of cosmic events. Background on the long history of fast radio bursts and how they are typically identified can be found through resources like NASA, which has tracked the evolution of FRB science since the first detection in 2007.
The Growing Problem of Orbital Interference
The discovery comes at a critical moment for observational astronomy. With more than 10,000 active satellites now in orbit — a number expected to balloon as constellations like Starlink and OneWeb expand — astronomers have raised increasingly urgent concerns about radio frequency interference and optical pollution of the night sky. The European Space Agency has documented a sharp rise in close-approach events involving debris, and organizations such as the European Space Agency have begun developing active debris removal missions to address the problem.
Karen Aplin, a space weather researcher at the University of Bristol, noted in commentary on the finding that electrostatic discharges from old satellites are a known but poorly characterized hazard. “These events are difficult to study because they happen quickly and unpredictably,” she said. The detection by ASKAP, which can capture nanosecond-scale events, may finally provide a way to systematically observe them.
What Comes Next
The team plans to comb through archival data to determine whether other unexplained nanosecond pulses might also originate from defunct satellites rather than deep space. If a significant fraction of past “burst” detections turn out to be terrestrial in origin, some catalogs of fast radio burst candidates may need to be revised. More broadly, the finding underscores the need for better coordination between space agencies, satellite operators, and the astronomy community to preserve the radio sky for scientific use. As humanity’s orbital footprint grows, distinguishing genuine cosmic signals from human-made noise will become an increasingly delicate task.
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