“A very serious threat”: NASA sounds the alarm, satellites destroy space astronomy
A spiral galaxy drowned in the light trails of satellites in low orbit. This image illustrates the increasing contamination of astronomical observations by the megaconstellations of telecommunications satellites. © NASA/Borlaff, Marcum, Howell (Nature, 2025)
From its orbit at an altitude of 540 kilometers, Hubble has been examining the universe for more than thirty years. But now a new problem arises: telecommunications satellites are crossing its field of vision more and more often. Between 2019 and today, their number has increased from 2,000 to 15,000 in low orbit. This is just the beginning.
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When space telescopes go blind
Alejandro Borlaff and his team at NASA Ames Research Center simulated the impact of 560,000 satellites on four space telescopes. Their results, published on December 3 in the journal Nature, outline a worrying future for astronomy. “This represents a very serious threat” for space telescopes, says the astrophysicist interviewed by theAFP.
The researchers modeled eighteen months of observations for Hubble, China’s Xuntian telescope, the American SPHEREx and the European ARRAKIHS. If all planned constellations become operational, 96% of images from three of these telescopes will show at least one satellite trail. Hubble fares relatively better with a third of its images affected, thanks to its narrower field of view.
Imagine that you are looking for asteroids potentially dangerous to Earth. An asteroid streaking across the sky looks exactly like a satellite. It becomes very difficult to distinguish the good from the bad.
Simulations of observations from the Hubble, SPHEREx, Xuntian and ARRAKIHS space telescopes contaminated by light trails from satellites planned for 2040. The galaxies in the background are obscured by this light interference.
© NASA/Borlaff, Marcum, Howell (Nature, 2025)
The brightness of these intrusions poses a major problem. Satellites reflect light from the Sun, but also that from the Earth and the Moon. “Imagine you are looking for asteroids potentially dangerous to Earth”explains Borlaff to theAFP. “An asteroid crossing the sky looks exactly like a satellite. It becomes very difficult to tell the good from the bad.”
The new giant models make the situation worse. With their solar panels of 3,000 square meters compared to 100 currently, these behemoths will shine as brightly as a planet from space. Their proliferation is explained by the growing needs of artificial intelligence in terms of connectivity.
The team proposes several options: limit the constellations to orbits lower than those of the telescopes, share the precise positions of the satellites, or simply launch fewer vehicles. But commercial competition makes this last option unlikely. By the end of the 2030s, humanity will have launched more satellites in a decade than in the first seventy years of the space age. Near the three quarters of current satellites belong to Elon Musk’s Starlinkbut this proportion should drop to 10% in the face of the arrival of new competitors.
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