If Elon Musk has his way, stargazing could soon be impossible.
Starlink, one of Musk’s businesses, sells high-speed internet access to places around the globe that traditional internet providers often can’t reach. In the process, the company has launched a fleet of satellites that orbit the planet so densely and visibly that they are often referred to as a man-made “mega-constellation”—and not everyone is happy about it.
The European Southern Observatory (ESO), an intergovernmental agency running some of the world’s most powerful space telescopes, cautions that further clogging up the night sky could have “devastating consequences” for the study of space here on Earth. That includes Musk’s dream of building a 1-million-satellite network of “orbital data centers” powered by endless beams of solar energy.
“Until now we have managed, but it’s getting worse,” Olivier Hainaut, ESO Directorate of Operations, said in the press release. For anyone observing space from the ground, satellites scatter light unpredictably and interfere with the imaging process.
In a new report, the ESO observes that the number of satellites orbiting the planet has skyrocketed since the world’s first trillionaire began flinging satellites into low Earth orbit in 2019. By last month, there were roughly 10,400 satellites in orbit from Starlink, a subsidiary of SpaceX. Prior to 2022, just 14,450 satellites had been launched into space ever across human history.
The ESO is proposing a limit of 100,000 “faint satellites, below naked eye visibility” as a ceiling that could limit the harm from having so many shiny objects in lower Earth orbit. To determine the limit, the group’s researchers ran simulations predicting how a projected flood of Starlink satellites could disrupt the world’s most powerful space telescopes and the results weren’t pretty.
For Europe’s flagship Very Large Telescope (VLT) located in Chile’s Paranal Observatory, the telescope’s field of view would be diminished by 28%, even in the best of circumstances with satellites not visible to the naked eye. If the satellites glow even a little brighter, they would start causing problems for other telescopes, like the Vera C. Rubin Observatory, which would find itself essentially blind for several hours every night.
“Satellites, illuminated by the Sun, are much brighter than distant galaxies,” Hainaut said. “When a satellite crosses what we observe, it makes a bright streak on our image, zapping whatever is behind it.”
Sophisticated space telescopes like the VLT are the result of many millions of dollars of investment and many years of scientific research and planning, making the issue of light pollution even more vexing. Telescopes like the VLT rely on extraordinarily sensitive equipment installed in some of the planet’s highest, driest places to study distant space phenomena, unfurling the mysteries of the universe.
Light pollution – and more on the way
In images, satellites show up as unwanted streaks, but they also generate light that brightens the night sky broadly. “Satellites too faint to be seen directly produce a veil of ‘diffuse’ light, while light from brighter satellites is ‘scattered’ in all directions as it passes through the atmosphere,” the ESO noted in its report. Both are a major problem for scientists studying the night sky.
Light pollution from satellites has already given the inky dark of the night sky an unwanted glow-up, but Starlink’s plans to scale up exponentially have astronomers even more worried. In a blog post announcing plans for the extraterrestrial data centers, Musk cheered the idea of limitless “compute.” “It’s always sunny in space!” he wrote.
SpaceX says that it is working to make its satellites dimmer to minimize light pollution, which occurs when sunlight bounces off of the satellite’s chassis or solar array, but environmental and scientific concerns haven’t given the erratic executive pause yet.
Musk has been predictably cavalier about the consequences. “There’s a lot of space up there, and so even when you’re talking thousands, or even, you know, up to a million satellites, you got plenty of room to move around up there,” Musk said in a video posted in June. “Space is really big, so it’s not like space is going to get crowded.”
Europe’s astronomical research experts disagree. One million space-based data center satellites floating in lower Earth orbit would have “drastic consequences” for the field of astronomy, according to the ESO report, which also expressed concern about plans by aerospace company Reflect Orbital to launch energy-generating mirrors in space.
“Low Earth orbit is a celestial seashore that provides immense value to modern life, from global connectivity to our clear access to the Universe,” Hainaut said. “However, we must manage the footprint of mega-constellations—from the light pollution affecting astronomy to the atmospheric effects of satellite re-entry—to ensure this resource remains pristine and accessible for future generations.”
