Elon Musk’s SpaceX satellites an ‘existential threat to astronomy’
SpaceX’s Starlink satellites are blinding radio telescopes and risk crippling vital research into the universe, astronomers have warned.
New footage from the Low Frequency Array (Lofar) radio telescope shows that satellites can be clearly seen as bright spots moving continuously across the field of view.
Experts from the Netherlands Institute for Radio Astronomy (Astron) have found that Starlink’s second-generation V2-mini satellites emit up to 32 times brighter “unintended radio waves” than satellites from the previous generation.
Starlink is currently launching around 40 satellites a week, and there are fears that radio astronomy from Earth will become impossible without mitigating measures.
Professor Jessica Dempsey, general and scientific director of Astron: “Every time you put an electric current through something you get unintended electromagnetic radiation, so we weren’t particularly surprised when the first Starlink satellites started showing up in the telescope.
“But frankly we were gobsmacked by how much brighter this generation of satellites is compared to the last one.
“We know it’s unintended, but they are 10 million times brighter than what we are trying to look for, and we have to talk about it now because it’s becoming an existential threat.
“We have had discussions and they have said they are working towards their next satellites being quiet, but we will believe it when we don’t see it.”
The Lofar telescope is the biggest radio telescope on Earth and is primarily based in the Netherlands, but it also has antennae spread across Europe, in countries including Britain, Germany, France, Sweden and Ireland.
It needs quiet skies because it is studying some of the lowest frequencies that can be observed from Earth, and which could reveal jets bursting from black holes or exoplanets.
Astronomers have previously warned that optical telescopes are struggling to deal with bright streaks of light reflecting off satellites.
In 2021, a signal that scientists first believed was the ground-breaking discovery of a gamma-ray burst from the oldest known galaxy in the universe, was actually a reflection of sunlight from the remnants of a Russian Proton rocket.
Starlink satellites orbit approximately 342 miles (550 kilometres) above Earth and are visible to the naked eye, often travelling as a train of bright lights across the night sky.
There are already 6,350 Starlink satellites in low Earth orbit (LEO), and the company has plans for a 42,000-strong mega-constellation in the coming years.
Plans show that the number of satellites launched into orbit could surpass 100,000 by the end of the decade, and in all, some 400,000 satellites have been approved globally for future launch.
On Earth, there are regulations to keep electromagnetic radiation at a minimum for health reasons, and also so it does not interfere with technology.
But although many satellite companies are actively working with astronomers to make their products darker and quieter there is little regulation to prevent launches or check they will not interfere with expensive and sensitive equipment.
Dr Robert Massey, deputy executive director of the Royal Astronomical Society (RAS), said: “What is the point of the pursuit of knowledge and all the investment that goes into that, if we’re going to see these facilities effectively crippled?
“I would call on SpaceX to pay heed to this research and work with the astronomical community to solve this. We have terrestrial standards on Earth so there is no excuse for not having them in space.
“It makes no sense for governments to spend tens or hundreds of millions on discovery science that inspires people only for companies to design satellites in this way. We need to pause for breath before we continue throwing these things into space.”
The new study involved two one-hour observation sessions on July 19, covering radio frequencies above and below the FM broadcast band.
During the observations, the team detected unintended electromagnetic radiation (UEMR) from almost all the Starlink satellites observed, including both first-generation and second-generation satellites.
“Compared to the faintest astrophysical sources that we observe with Lofar, unintended electromagnetic radiation from Starlink satellites is 10 million times brighter,” said Dr Cees Bassa, an astronomer at Astron, and the lead author of the study.
“This difference is similar to the faintest stars visible to the naked eye and the brightness of the full Moon.
“Since SpaceX is launching about 40 second-generation Starlink satellites every week, this problem is becoming increasingly worse.”
‘Humanity approaching an inflexion point’
The Lofar team is now in the process of assessing what scientific projects will be impacted by the Starlink “noise”.
Other radio observatories are also concerned by the findings, including astronomers at the Square Kilometre Array Observatory (SKAO) which is currently being built in Australia and South Africa.
“Humanity is clearly approaching an inflexion point where we need to take action to preserve our sky as a window to explore the universe from Earth,” said Federico Di Vruno, spectrum manager, at SKAO.
“Satellite companies are not interested in producing this unintended radiation, so minimising it should also be a priority in their sustainable space policies.
“Starlink is not the only big player in low Earth orbit, but they have a chance to set the standard here.”
SpaceX was approached for comment.
The new research was published in the journal Astronomy and Astrophysics.