Starlink satellite radiation still impacting radio astronomy

Leaking radio signals from Starlink satellites continue to disrupt radio astronomy even in protected areas, raising further concerns about the future of astronomy.
John Loeffler

Starlink satellites are still interfering with radio astronomy despite efforts to limit their impact, raising the level of concern astronomers have for the future of this important avenue of scientific exploration.

Astronomers at the Low Frequency Array (LOFAR) telescope centered in the Netherlands observed dozens of SpaceX Starlink satellites and found they continued to emit "unintended electromagnetic radiation" from their electronics, according to an International Astronomical Union statement this week.

"We report on observations of 68 satellites belonging to the SpaceX Starlink constellation with the LOFAR radio telescope," an international team of researchers writes in a study published this week in the journal Astronomy & Astrophysics. "Radiation associated with Starlink satellites was detected at observing frequencies between 110 and 188 MHz, which is well below the 10.7 to 12.7 GHz radio frequencies used for the downlink communication signals."

That means that this interference isn't from actual communication from the satellites, but rather their presence in radio-sensitive regions that might affect astronomical observation in the affected spectrum.

The radio signals from distant objects in the universe, like a galaxy or the activity of light-faint objects like white dwarfs, can be extremely hard to discern amid the typical radio noise that comes from terrestrial sources. As such, radio telescope arrays are often located in very isolated regions with as little radio interference as possible.

SpaceX's Starlink satellites present a very different problem though. With plans for tens of thousands of satellites in low Earth orbit to provide internet connectivity, the satellite "constellation" — along with several others planned by other companies around the world — threaten to completely saturate these radio-quiet regions with noise that will make their operation functionally impossible.

“Our simulations show that the larger the constellation, the more important this effect becomes as the radiation from all the satellites adds up. This makes us worried not only about the existing constellations but even more about the planned ones — and also about the absence of clear regulation that protects the radio astronomy bands from unintended radiation,” said paper co-author Benjamin Winkel from the Max Planck Institute for Radio Astronomy (MPIfR) in Germany.

The researchers emphasize that SpaceX isn't violating any laws or regulations, and the company has been proactive in trying to ameliorate Starlink satellites' impacts. The problem is that other constellation operators might not be as cooperative, and without international rules around satellite radio radiation (unintentional or otherwise), the time to address the problem is now, before these constellations take over the night sky.

“We believe that the early recognition of this situation gives astronomy and large constellation operators an opportunity to work together on technical mitigations pro-actively, in parallel to the necessary discussions to develop suitable regulations,” paper co-author Gyula Józsa from MPIfR and Rhodes University in South Africa said.

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