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| SpaceX Starlink satellites |
The proliferation of satellite constellations orbiting Earth is generating more radiation than ever before, including in protected radio wavelength bands reserved for scientific purposes like radio astronomy.
The latest generation of Starlink satellites, particularly the v2mini and v2mini Direct-to-Cell models, are responsible for up to 32 times more radiation leakage than their predecessors.
This radiation leakage poses a significant threat because it interferes with radio frequencies that astronomers rely on to observe distant celestial objects. Some of this interference comes from radio wavelengths that are meant to remain free from human-generated signals to protect sensitive astronomical observations.
When this issue was first highlighted in 2023, SpaceX stated that it was working on a solution. However, with the number of satellites in orbit now totaling 6,398, the situation has worsened rather than improved.
"We’ve initiated a program to monitor unintended emissions from various satellite constellations," explains Cees Bassa, an astronomer at the Netherlands Institute for Radio Astronomy (ASTRON). "Our observations reveal that the second-generation Starlink satellites emit stronger signals over a wider range of radio frequencies compared to the first generation."
He further elaborates, "Compared to the faintest astrophysical sources we study with LOFAR, the electromagnetic radiation from Starlink satellites is 10 million times brighter. The scale of this interference is similar to comparing the faintest stars visible to the naked eye to the brightness of the full Moon."
The problem is compounding, Bassa notes, as SpaceX continues to launch about 40 new second-generation satellites every week.
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| A timelapse of a constellation of Starlink satellites as seen during astronomical observations. (GMN) |
Crowded Skies Threaten Both Night and Radio Observations
SpaceX is not the only company contributing to the crowding of Earth's skies. OneWeb has launched 634 satellites, Amazon aims to deploy over 3,000, and China’s Spacesail Constellation plans to add 15,000. The visible streaks these satellites leave on long-exposure images taken at dusk are a growing concern for optical astronomers, but the issue extends beyond visible-light pollution.
A study conducted last year revealed that constellation satellites are leaking radio waves outside their allocated communication frequencies (10.7 to 12.7 gigahertz), with some of the leakage occurring in the 150.05 to 153 megahertz range—a frequency band used for radio astronomy.
The most recent study analyzed data from the LOw Frequency ARray (LOFAR), a network of around 20,000 radio antennas spread across 52 locations in Europe. During two one-hour observation sessions using LOFAR’s six central stations, researchers detected emissions from 97 Starlink satellites.
These signals fell within the 110 to 188 MHz range, with radiation from the v2mini satellites significantly more intense than those from the first-generation models.
Call for Regulatory Action
Currently, there are no international regulations to address the leakage of unintended electromagnetic radiation from satellite constellations. Researchers are calling for such rules to be established, warning that the more satellites that enter low-Earth orbit, the greater the cumulative impact of this radiation will become.
The team also urges SpaceX to analyze their data and identify the source of the radiation leakage, so they can fix the issue before it spirals further out of control.
"Humanity is approaching a critical moment where we must act to preserve our sky as a window to explore the universe from Earth," says Federico Di Vruno, an engineer with the SKA Observatory. "Satellite companies don't want to produce unintended radiation, so minimizing it should be a priority in their sustainable space policies."
Di Vruno adds that Starlink has an opportunity to set the industry standard for reducing this type of interference, especially as other major players in low-Earth orbit emerge.
The Broader Impact of Radio Astronomy
The implications of these issues extend beyond space research. The technological advancements driven by radio astronomy have led to breakthroughs we rely on every day, from Wi-Fi to GPS and medical imaging. Interference that hampers radio astronomy could have unforeseen consequences for both science and society.
"We just need regulators to support us, and for the industry to meet us halfway," says ASTRON General and Scientific Director Jessica Dempsey. "Without mitigating these issues, soon the only constellations we’ll be able to see will be human-made."
At the time of writing, SpaceX has not responded to requests for comment from ScienceAlert.
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