Imagine staring up at the night sky, admiring the beauty of a shimmering field of stars when, all of a sudden, a bright point of light begins to float across your field of view. It's dazzling, and an absolute nuisance to the casual stargazer. You squint, you can't see the stars anymore; their gentle glow drowned out by the shining ball in the sky. Now imagine if there were a half dozen of these all dotted across the starscape, and you happened to be an astronomer trying to catch a glimpse of the dim light of a distant galaxy through one of the world's most powerful telescopes.
There are over three thousand first-generation Starlink satellites orbiting the Earth right now. Launched by Elon Musk's aerospace firm SpaceX between 2019 and 2021, these satellites orbit in the range of 540 to 570 kilometres above the surface of the Earth – that is, low Earth orbit – and provide wireless internet access to even some of the most remote places on the planet. A 2022 study titled "A Case for Space Environmentalism" (A. Lawrence et al.) estimates that SpaceX launches alone have almost doubled the number of active satellites in orbit since 2018. It also found that these first-generation satellites are already causing massive interference for observatories and telescopes, such as the Victor M. Blanco Telescope in Chile that – as part of the worldwide Dark Energy Survey – captured a 333-second exposure of the sky in 2019 that is polluted with streaks of bright light caused by passing Starlink satellites.
Starlink satellites pass in front of the Victor M. Blanco telescope, seen as white streaks.
As communication satellites, Starlink constellations emit massive amounts of radio waves that can cause noise and interference with radio telescopes such as the Lovell Telescope at Jodrell Bank, in Cheshire, but due to their size and construction they can also catch the sunlight and cause strong optical interference. Space debris and other Artificial Space Objects (ASOs) can often spin in random or unpredictable movements that may cause them to reflect a strong but brief burst of sunlight directly down to an observer on the ground, leading to mislabelled observations that can set back scientific research by months or even years. In 2020, scientists from China, Japan, and the USA (L. Jiang et al.) identified a brief flash of near-infrared radiation as a sign of a gamma-ray burst (GRB) event – one of "the most luminous explosions in the Universe" – at a redshift value of approximately 11.
To put this into perspective, a higher redshift value indicates an event takes place further away from us, the observer – or rather, the light from it takes a longer amount of time to reach us. The furthest GRB event that had been observed to date had a redshift value of approximately 9.4, so this new observation exceeded that by a huge margin. GRB events are explosions that are so massive, they are trumped in strength only by the Big Bang itself, and scientists managed to pinpoint this alleged event to a galaxy lovingly dubbed "GN-z11", one of the farthest galaxies from Earth ever discovered. This was a groundbreaking observation and was swiftly published in the journal Nature in December that year. This was such an unbelievable discovery, however, that scientists from all around the world double-checked the findings of the original team and, in 2021, a team from the Adam Mickiewicz University in Poland (M. Michałowski et al.) proved that the infrared flash – indicative of a once-in-a-lifetime event – was, in fact, no more than a reflection of sunlight off the discarded upper stage of a Russian Proton rocket launched from Kazakhstan in February of 2015.
The scientific community pushed hard in favour of measures to mitigate these unintended optical phenomena. In February of 2023, SpaceX began launching their line of second-generation satellites which, allegedly, included measures to combat the light pollution and sunlight reflections that plagued the earlier models. However, an observation conducted by the Netherlands Institute for Radio Astronomy (ASTRON) in 2024 found that this new generation of satellites can emit up to 32 times more radio interference than their predecessors, effectively blinding radio telescopes and creating severe difficulties in astronomical surveys. When approached for comment, one professor of astrophysics at the University of Central Lancashire noted: "Many astrophysicists are concerned about the impact of the constellations of satellites on their ability to conduct observations of faint objects such as distant galaxies and planets outside the solar system," further adding "This matters because then you can't do astronomy."
Starlink 1619 passes in front of the Hubble Space Telescope.
But why is this problem emerging only now? In the past, communications satellites would be suspended in geostationary orbit, meaning that they would match the rotation of the Earth and would therefore remain in one place in the sky – relative to an observer on the ground. However, Musk's Starlink satellites are in a low Earth orbit, as it is cheaper to launch satellites lower rather than wasting fuel trying to position them statically, and as such their trajectories can unintentionally cross the field of view of key research equipment (whether in orbit or on the ground).
It can be argued that stronger regulations are needed to prevent private enterprises from interfering with important scientific research, but that raises the question: who really controls space? One workaround is to invest more in high-altitude or outer space telescopes. In 2023 the European Space Agency launched Euclid, a space telescope that joins Gaia and the James Webb Space Telescope in orbit at a point between the Earth and Sun at almost 1.5 million kilometres beyond Earth's orbit, well out of reach of any pesky polluting satellites.
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