Starlink satellites are blinding astronomers' view of space

Efforts to study the universe are being hindered by radio waves emitted from the Starlink's extensive satellite network, according to a new study.

The Starlink "constellation" consists of more than 6,300 working satellites orbiting the planet at 550km, accounting for more than half of all satellites surrounding Earth.

All those satellites create radio "noise" — known as unintended electromagnetic radiation, or UEMR.

While the Starlink network allows the delivery of high-speed internet services across the planet — a  service benefiting communities without reliable internet infrastructure — satellite noise risks undermining the work of astronomers.

A study led by the Netherlands Institute for Radio Astronomy (ASTRON) found second-generation "V2" Starlink satellites — which account for around a third of the company's network — emit UEMR at levels 32 times brighter than the brand's V1 infrastructure.

Starlink's first-edition satellites, which currently comprise most of the network, have already been in the crosshairs of the astronomy community when their UEMR were first detected polluting research as recently as 2022.

Benjamin Winkel, a scientist at the Max Planck Institute for Radio Astronomy who contributed to analysis, said the interference is "blinding" the work of the research community.

"While the generation 1 satellites indeed got dimmer in the last year — so Starlink actually did something to them [to reduce radio leaks] — the new generation unfortunately seem to be brighter again," said Winkel.

"When we say ‘blinded' it means your eye collects too much light for you to see anything, you are getting saturated. This is exactly what happens with our radio telescopes," he added.

Interference from low-earth satellites is blocking our view of space

The number of orbiting satellites from all operators could increase to 100,000 by 2030. 

With satellites already visible in the night sky with the naked eye, this huge increase in the number of near-Earth orbiters from all operators has the potential to further blind astronomers using both optical and radio telescopes.

"My colleagues told me that they are really frightened of the future," Winkel said.

"There should be some improvements if they really want to observe in a good manner."

These latest findings are particularly devastating for radio telescope observations.

The consequence could mean light "smears" appearing on the images obtained by these powerful instruments. These light leaks cannot always be removed, tarnishing valuable observation data.

New satellite regulations may be needed 

Cellphone networks and radio pollution from other ground level electronic sources can also interfere with space observations, but these emissions are tightly controlled by regulators like the International Telecommunications Union.

Once space side, it's a different story. With few regulations over satellite operators, the research community is reliant on forging good faith interactions with companies putting technology into space.

For the most part, things have been positive, with Starlink having previously made acceptable modifications to its V1 fleet to reduce radio noise.

In August, Elon Musk's SpaceX (the owner of Starlink) elaborated on its efforts to steer radio emissions away from telescope line-of-sight, a technique known as the telescope boresight avoidance method.

In a statement it said "SpaceX maintains an open invitation to other radio astronomy organizations from around the world to implement the approach to protect their important scientific research."

Starlink isn't the only culprit when it comes to future astronomical interference, however.

An emerging player in the space internet game is OneWeb, which has about 630 satellites in orbit. Amazon's Kuiper project only has two satellites in orbit, but growth is expected as it stakes its claim for the consumer broadband dollar.

It's big business, but together these companies are taking essential real estate from space researchers. Regulation is vital, but that takes time, and so a good faith undertaking by satellite operators to continually plug their radio leaks looks to be the best short-term solution.

"There is no way to make any electrical or electronic apparatus without this kind of leakage," Winkel said. "The question always asked is: how much is leaked?"

"Consumer devices… fall under some kind of regulation for this leakage, also for health and safety issues [and] not to interfere with other devices. But for satellites that is not the case, so this is really a grey zone," he said.

Edited by: Fred Schwaller

Primary source

Bright unintended electromagnetic radiation from second-generation Starlink satellites. Published by C. G. Bassa, F. Di Vruno, B. Winkel, G. I. G. Józsa, M. A. Brentjens and X. Zhang in Astronomy & Astrophysics (2024) https://doi.org/10.1051/0004-6361/202451856