Nevermind the light pollution – the ever-growing swarm of Starlink satellites orbiting Earth are creating a fresh unknown problem for astronomers: They’re leaking electromagnetic radiation.
Germany’s Max Planck Institute for Radio Astronomy made the determination after observing 68 of SpaceX’s 4,000-plus Starlink satellites using the Netherlands-based Low Frequency Array (Lofar). From those satellites, Planck boffins said, “unintended electromagnetic radiation” was detected emanating from what researchers believe to be the onboard electronics.
“The unintended radiation could impact astronomical research,” the institute said.
According to the institute, 47 of the 68 satellites observed as they passed through Lofar’s field of view were emitting “previously unknown spurious radiation in the frequency range between 110 and 188 megahertz,” a portion of which overlaps with protected radio frequencies for astronomical observations.
Despite the issue, the institute said that SpaceX isn’t violating any rules by emitting spurious radiation, which isn’t covered by any international satellite regulations. The institute said it plans additional observations, and expects similar unintended emissions coming from non-SpaceX satellites in low-Earth orbit.
Far from powerful, but close enough to matter
According to the Planck Institute, the radiation being emitted by the SpaceX satellites is miniscule – in the neighborhood of just a few microwatts, or around a million times weaker than the emissions from a mobile phone.
Despite that weakness, the close proximity of Starlink satellites to Earth means those microwatts are comparable or even stronger than the radio waves that reach Earth from distant celestial objects. Fortunately for skywatchers, SpaceX is in “close contact” with the Planck Institute over its EM-leaking satellites.
“The company has offered to continue to discuss possible ways to mitigate any adverse effects to astronomy in good faith,” the Planck Institute said, adding that SpaceX has already introduced changes in the second generation of its Starlink satellites to mitigate the emissions.
Along with those mitigations, Starlink’s Gen 2 satellites are also designed to lessen the other big issue they pose to astronomers: their reflections.
As of early 2022, streaks of light from Starlink satellites flying through astronomy shots were present in nearly a fifth of observations. Early this year, SpaceX signed an agreement with the US National Science Foundation to mitigate the problem, but more recent reports indicate it’s still an issue; accounting for the speed of satellite launches also means SpaceX simply hasn’t had the time to replace all its overly shiny sats. Some researchers have even taken to writing code to detect and eliminate satellite trails from their astronomical snapshots.
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To compound matters, SpaceX’s second generation satellites are too heavy to launch in an economically feasible manner without SpaceX’s yet-to-reach-orbit monster rocket Starship. Many of the fixes they include will have to wait until when, or if, that actually happens.
In the meantime, SpaceX has come up with Starlink V2 Mini satellites, a first batch of which were hauled into orbit earlier this year. Like their larger counterparts, the V2 Minis are designed to reduce light pollution, but it’s unclear how much EM leak prevention is built into the Minis that have already reached orbit, or any other satellites it plans to launch before Starship makes orbit.
We’ve asked SpaceX to comment. ®
