Mysterious fast radio burst turns out to be from long-dead NASA satellite

Relay 2 satellite. Credit: NASA

A team of astronomers and astrophysicists affiliated with several institutions in Australia has found that a mysterious fast radio burst (FRB) detected last year originated not from a distant source, but from one circling the planet—a long-dead satellite. The team has posted a paper outlining their findings on the arXiv preprint server.

On June 13, 2024, a team working at the Australian Square Kilometer Array Pathfinder heard something unexpected—a potential FRB that lasted less than 30 nanoseconds. The pulse, they note, was so strong that it eclipsed all of the other signals coming from the sky.

It was originally assumed that the signal had come from some distant object because that is the case for most FRBs. But subsequent analysis showed that it had come from a nearby source.

Further analysis revealed that the source was a long-dead NASA satellite called Relay 2. The research team also found that the reason the signal was so strong was the satellite was passing directly over them when the FRB occurred. It also accounted for its unusual clarity and well-defined nature.

Relay 2 was sent into orbit in 1964. The satellite had been launched just two years after Relay 1; both were experimental communications satellites. Relay 2 had worked as planned for less than a year, at which time it stopped operating; its transponders stopped working in 1967. From that point on, no signals have ever been heard from the satellite—until now.

The dedispersed burst. Total burst power at Nyquist resolution (points—lines to guide the eye only) after dedispersion and coherent addition over 19 antennas according to the nearfield fit. Credit: arXiv (2025). DOI: 10.48550/arxiv.2506.11462

The research team does not believe the satellite suddenly came back to life for a moment. They suggest it is far more likely that an electrostatic charge built up on the craft and reached a certain point and then discharged. Such discharges have been seen before, the team notes. Another possibility is that the craft was struck by a micrometeoroid, releasing a very small cloud of plasma.

The findings could lead to the development of new tools for studying signals coming from space, whether near or far, and possibly new ways to monitor the movement of dead satellites.

Written for you by our author Bob Yirka, edited by Lisa Lock , and fact-checked and reviewed by Robert Egan —this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You’ll get an ad-free account as a thank-you.

More information: C. W. James et al, A nanosecond-duration radio pulse originating from the defunct Relay 2 satellite, arXiv (2025). DOI: 10.48550/arxiv.2506.11462 Journal information: arXiv