Low Earth orbit is filling with satellites, and space telescopes are beginning to notice. A new study published in Nature finds that reflections from large satellite constellations could interfere with most images taken by some current and future space observatories. Because these missions rely on long exposures to detect extremely faint objects, even brief satellite crossings can hide objects or reduce the amount of usable data scientists collect.
The researchers modeled how satellite populations might grow in the coming decades. In one scenario, the number of active satellites reaches roughly 560,000. In a higher-growth projection, that number approaches one million. As those numbers increase, so does the likelihood that a satellite crosses a telescope’s field of view during an exposure. If most exposures contain satellite streaks, survey missions may deliver less complete and less precise data than intended.
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Satellite Megaconstellations in Low Earth Orbit
Low Earth orbit once held only a few thousand operational satellites. Today, commercial broadband networks are deploying them by the thousands, with many more planned. The study focuses on how that rapid expansion changes the observing environment for space telescopes.
As more satellites share the same orbital region as space observatories, the chances of a crossing increase simply because there are more objects in motion. Telescopes that take long exposures are more likely to capture a crossing. Wide-field missions face even greater risk because they image larger portions of the sky at once.
The simulations incorporated satellite brightness, orbital placement, and each telescope’s observing pattern. As satellite density rises, crossings increase sharply. The effect is cumulative; it is not a single bright satellite that creates the problem, but the growing number moving through the same region of space.
Light Pollution in Space
The team applied its analysis to four missions: the Hubble Space Telescope, NASA’s SPHEREx mission, the European Space Agency’s ARRAKIHS mission, and China’s Xuntian telescope. Although these observatories differ in design and purpose, all showed rising levels of interference as satellite numbers increased.
With roughly 560,000 satellites in orbit, more than 96 percent of exposures from SPHEREx, ARRAKIHS, and Xuntian contained at least one satellite trail. In projections approaching one million satellites, multiple streaks frequently appeared in a single image. Hubble, which observes a smaller patch of sky at a time, was less affected but still saw more than one-third of its exposures disrupted in the lower-density scenario.
Satellite trails increase brightness along their paths and can saturate detector pixels, masking objects beneath them. Even when software identifies and removes a streak, some residual light remains. That added brightness makes faint galaxies and diffuse structures harder to detect. For missions designed to map large areas of sky or measure subtle patterns in cosmic structure, repeated interference reduces the depth and precision of the final data set.
Long-Term Consequences for Space Astronomy
The authors describe this effect as a new form of space-based light pollution. Unlike city lights on Earth, these reflections occur within the same orbital region where telescopes operate. As satellite populations grow, the assumption that space provides a consistently dark observing platform becomes less reliable.
Over the lifetime of a survey mission that gathers thousands of exposures, small losses accumulate. If most images contain at least one streak, scientists must either discard affected regions or accept lower-quality data. Either outcome reduces the total scientific return.
Possible mitigation measures include lowering satellite reflectivity, adjusting orbital placement, improving tracking data, and refining correction software. But the simulations show that once satellite numbers reach very high levels, interference cannot be fully eliminated.
Low Earth orbit now supports both expanding commercial networks and major astronomical observatories. As satellite deployment continues, unwanted reflected light will become a structural feature of the space environment — one that future missions must plan for from the outset.
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