A recently-launched bright satellite could pose a threat not only to visible astronomy, but also radio astronomy observations, causing the International Astronomy Union (IAU) to release a statement expressing concern over the growing number of bright satellites.

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BlueWalker 3 (BW3) is a prototype for a new constellation of around 100 telecommunications satellites called BlueBird.

A group of SpaceX Starlink satellites in the night sky over Uruguay. Photo by Mariana SUAREZ / AFP via Getty Images
A group of SpaceX Starlink satellites in the night sky over Uruguay. Photo by Mariana SUAREZ / AFP via Getty Images

However, shortly after it was launched on 10 September 2022, astronomers noted it was extremely bright.

The IAU’s Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS) has collated measurements of the satellite, finding it reaches around magnitude +1.0 at its brightest – similar to Antares, the 15th-brightest star in the sky.

In addition, BW3 uses the same radio frequencies as terrestrial mobile phones, but isn’t bound by requirements to adhere to radio quiet zones around astronomical observatories.

"Frequencies allocated to cell phones are already challenging to observe in, even in the radio quiet zones we have created for our facilities," says Philip Diamond, director general of the Square Kilometre Array Observatory – a huge new radio telescope that began construction on 5 December 2020.

"New satellites such as BlueWalker 3 have the potential to worsen this situation and compromise our ability to do science, if not properly mitigated."

Companies like Amazon argue their satellites are helping to achieve global connectivity. Photo by Alex Wong/Getty Images
Companies like Amazon argue their satellites are helping to achieve global connectivity. Photo by Alex Wong/Getty Images

AST SpaceMobile, which operates BW3, has started talks with the IAU, while the Federal Communications Commission (FCC) has created a special office to address satellite constellations, ensuring they perform their important roles in global communications without affecting the scientific and cultural importance of the night sky.

"BlueWalker 3 is a big shift in the constellation satellite issue and should give us all reason to pause," says Piero Benvenuti, director of the IAU CPS.

More satellite launches are on the way

Comment: Astronomer Chris Lintott

A SpaceX Falcon 9 rocket carrying 40 broadband internet satellites for OneWeb heads for orbit. Photo by Paul Hennessy/SOPA Images/LightRocket via Getty Images
A SpaceX Falcon 9 rocket carrying 40 broadband internet satellites for OneWeb heads for orbit. Photo by Paul Hennessy/SOPA Images/LightRocket via Getty Images

"If AST SpaceMobile has its way, there will be 243 satellites as bright as BW3.

OneWeb, partly owned by the British government, plans for 648.

Amazon’s Project Kuiper anticipates 3,276 in orbit, while SpaceX already has more than 3,000 aloft and plans many more.

These satellites will alter our view of the night sky, interfere with our attempts to spot Earth-threatening asteroids and, according to disturbing new research, may have a significant effect on the upper atmosphere as satellites burn up.

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The solution is for governments to stop, now, and work out how we want to use the precious space above our heads.

Leaving it to competing companies is not going well."

cps.iau.org

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This story originally appeared in the February 2023 issue of BBC Sky at Night Magazine.

Authors

Elizabeth Pearson
Ezzy PearsonScience journalist

Ezzy Pearson is the Features Editor of BBC Sky at Night Magazine. Her first book about the history of robotic planetary landers is out now from The History Press.

Chris Lintott, University of Oxford astronomer, BBC The Sky at Night presenter.
Chris LintottAstrophysicist

Chris Lintott is a Professor of Astrophysics at the University of Oxford and a co-host of BBC's The Sky at Night.