The boom in space startups like Elon Musk’s SpaceX continues to be bad news for astronomers, as new satellite constellations start to interfere with telescopes based in space.
Astronomers have for some time complained that satellites leave bright trails on images produced from their ground-based telescopes. Back in 2019, SpaceX CEO Elon Musk responded by suggesting that astronomers should move their telescopes into space instead, noting that that the Earth’s atmosphere already interfered with ground-based observations.
But a new study published in Nature Astronomy on Thursday finds that the growth in satellites are hindering the operations of space telescopes too.
The study’s authors, led by Sandor Kruk of Germany’s Max-Planck Institute for Extraterrestrial Physics, analyzed a dataset of images from the Hubble Space Telescope, which sits almost 540 km above the Earth’s surface. The telescope orbits below other satellites like those used in SpaceX’s Starlink system, which can sit as much as 550 km above the Earth.
Kruk and his colleagues found that, between 2009 and 2020, there was a 3.7% chance that a satellite trail would taint one of Hubble’s photos. That number jumps to 5.9% in 2021, which corresponds to the rise of satellite constellations like Starlink and OneWeb.
And the number of satellites—and thus the likely number of photos affected by their trails—has grown since 2021. SpaceX alone has launched over 1,400 more Starlink satellites since the beginning of 2022.
SpaceX now has more than 3,700 Starlink satellites in orbit, according to data compiled by Jonathan McDowell, an astronomer at the Harvard–Smithsonian Center for Astrophysics. SpaceX has submitted plans to put over 40,000 satellites in orbit, though COO Gwynne Shotwell suggested last year the company might not need quite that many to provide “good service globally.”
Other organizations are planning their own satellite constellations: China is reportedly planning its own network of 13,000 satellites—in part to monitor and potentially suppress Starlink, according to the South China Morning Post.
“With the growing number of artificial satellites currently planned, the fraction of Hubble Space Telescope images crossed by satellites will increase in the next decade and will need further close study and monitoring,” write the authors of the study.
That may force astronomers to move telescopes further away from the Earth to get clearer images–which in turn would increase the cost and complexity of such missions. ““There will be science that can’t be done. There will be science that’s significantly more expensive to do,” McDowell told the New York Times.
(Fortunately, some of the newest and most powerful telescopes, like the James Webb Space Telescope, are much further away, around 1.5 million kilometers from the Earth.)
Satellite modifications
Scientists have long grumbled about the interference posed by bright satellites crossing the sky. SpaceX has tried to account for their concerns by testing new satellite designs that are less reflective, such as its DarkSat design, which uses a less reflective coating. Astronomers note that these experimental designs do work in lowering brightness, but not by enough to remove interference entirely.
To make matters potentially worse, SpaceX is now launching larger satellites that astronomers say are even brighter than earlier iterations.
SpaceX did not immediately respond to Fortune’s request for comment.
SpaceX is barreling ahead with its mission of providing satellite internet across the world. Screenshots of announcements posted to social media suggest that SpaceX will soon announce a Global Roaming service that would provide internet access almost anywhere in the world. The service would cost $599 upfront, followed by a $200 subscription payment charged monthly.
