For decades, radio astronomers have relied on quiet patches of the sky to detect the faintest signals from the early universe, whispers from a time before the first stars were born. But that silence is now being disturbed. A recent study has revealed that SpaceX’s Starlink satellites are producing unintended radio signals that are flooding the frequencies astronomers need most. These leaks are strong enough to obscure the weak emissions from cosmic hydrogen, which radio telescopes are designed to detect.
A team led by Steven Tingay of Curtin University and the International Centre for Radio Astronomy Research (ICAR) has pinpointed the source of the interference using a prototype station of the Square Kilometre Array-Low (SKA-Low) located in the radio-quiet desert of Western Australia. Over 29 days, they recorded more than 2.4 million full-sky images across 24 frequency bands. Sophisticated software was then used to match unexpected bursts of radio brightness to the paths of passing satellites. By the end of the survey, the team had identified 1,806 individual Starlink satellites leaking signals, around 28 percent of the constellation at the time.
The interference is not subtle. In the protected 170 MHz band, which is crucial for early-universe research, some of the satellites appeared in nearly one-third of all images. Two distinct types of emissions were detected: a broadband hum across nearly a full megahertz of bandwidth and a narrower tone emitted every 100 seconds at 137.05 MHz. These narrow pulses reached intensities of seven million Janskys, far brighter than the entire Milky Way at those frequencies.
What makes this situation even more troubling is that these frequencies fall within bands reserved by the International Telecommunication Union (ITU) for radio astronomy. Despite that, no rules are currently being broken because the emissions are unintentional, and the regulations only apply to deliberate transmissions. The result is a regulatory gray zone in which harmful interference is legal by default.
The implications for astronomy are dire. Instruments like SKA-Low are being built to study the “cosmic dawn,” the era roughly 13 billion years ago when the first stars and galaxies formed. Detecting the faint radio glow from neutral hydrogen during this time is already a tremendous technical challenge. Now, with tens of thousands of satellites in orbit, many of which are emitting noise at critical frequencies, the task becomes nearly impossible.
While SpaceX has taken steps to reduce visible light pollution from its satellites by altering the angle of solar panels to avoid sun reflections, no similar measures have yet been implemented to reduce radio leakage. However, possible solutions exist. Better shielding around the onboard electronics or hardware tweaks could prevent stray signals from escaping. Failing that, software on Earth could filter out the interference, though Tingay warns that the processing demands may soon exceed those of the scientific analysis itself.
Some form of cooperation or regulation appears urgent. Satellite operators already turn off internet beams when passing over major astronomical observatories. Extending this blackout to other electronic emissions could significantly reduce the problem. The research community is also beginning to advocate for updated international standards that would limit unintended emissions, similar to existing regulations for consumer electronics. Such guidelines would give satellite designers a clear target and allow national agencies to certify systems before launch.
The Starlink fleet is only the beginning. Amazon’s Kuiper, OneWeb-Eutelsat, and China’s G60 network all plan to launch thousands more satellites into low Earth orbit. Without updated rules, the combined leakage from these constellations could permanently turn the radio sky into broadband static.
With SpaceX currently launching new Starlink units at a rate of up to 23 per week, time is running out. The longer the regulation is delayed, the harder it will become to reclaim the clean sky that radio astronomy depends on. Tingay says, “The emissions are not regulated right now, but discussion has started.” For the sake of future cosmic discovery, the hope is that action will follow soon.
