The Radio Interference of Starlink Satellites: A Problem for Astronomy and Our Universe

Monday - October 16 2023, 03:21 UTC - 1 year ago

In new research accepted for publication in Astronomy and Astrophysics Letters, it was discovered that Starlink satellites are "leaking" radio signals that could interfere with radio astronomy. These signals are bright enough to appear as strong as cosmic sources, posing a problem to our understanding of the universe. Solutions to this issue are currently being considered, but the satellite operators may not be doing anything wrong.

When I was a child in the 1970s, seeing a satellite pass overhead in the night sky was a rare event. Now it is commonplace: sit outside for a few minutes after dark, and you can’t miss them.

Thousands of satellites have been launched into Earth orbit over the past decade or so, with tens of thousands more planned in coming years. Many of these will be in "mega-constellations" such as Starlink, which aim to cover the entire globe.

These bright, shiny satellites are putting at risk our connection to the cosmos, which has been important to humans for countless millennia and has already been greatly diminished by the growth of cities and artificial lighting. They are also posing a problem for astronomers—and hence for our understanding of the universe.

In new research accepted for publication in Astronomy and Astrophysics Letters, my colleagues and I discovered Starlink satellites are also "leaking" radio signals that interfere with radio astronomy. Even in a "radio quiet zone" in the outback of Western Australia, we found the satellite emissions were far brighter than any natural source in the sky.

A Problem for Our Understanding of the Universe .

Our team at Curtin University used radio telescopes in Western Australia to examine the radio signals coming from satellites. We found expected radio transmissions at designated and licensed radio frequencies, used for communication with Earth. In the following video, Starlink satellites emit bright flashes of radio transmission (shown in blue) at their allocated frequency of 137.5 MHz. However, we also found signals at unexpected and unintended frequencies.

We found these signals coming from many Starlink satellites. It appears the signals may originate from electronics on board the spacecraft. In the below video, we see constant, bright emissions from Starlink satellites at 159.4 MHz, a frequency not allocated to satellite communications.

Why is this an issue? Radio telescopes are incredibly sensitive, able to pick up faint signals from countless light-years away. Even an extremely weak radio transmitter hundreds or thousands of kilometers away from the telescope appears as bright as the most powerful cosmic radio sources we see in the sky. So these signals represent a serious source of interference.

And specifically, the signals are an issue at the location where we tested them: the site in Western Australia where construction has already begun for part of the biggest radio observatory ever conceived, the Square Kilometer Array (SKA). This project involves 16 countries, has been in progress for 30 years, and will cost billions of dollars over the next decade. Huge effort and expense has been invested in locating the SKA and other astronomy facilities a long way away from humans. But satellites present a new threat in space, which can’t be dodged.

What Can We Do About This? .

It’s important to note satellite operators do not appear to be breaking any rules. The regulations around use of the radio spectrum are governed by the International Telecommunications Union, and they are complex. At this point there is no evidence Starlink operators are doing anything wrong. Solutions to this potential issue are currently being considered, including the possibility of future satellite technology that more carefully manages its radio emissions.