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Recent research shows that SpaceX’s Starlink satellites, which can connect directly to smartphones, shine nearly five times brighter in the sky than traditional Starlinks.
SpaceX plans to form what it calls “a cell phone tower in space” with thousands of direct-to-cell (DTC) satellites orbiting Earth that provide service directly to unmodified smartphones “wherever you can see the sky.” The higher luminosity of these DTCs compared to regular Starlinks is partly because they orbit the Earth at just 217 miles (350 kilometers) above the surface, which is lower than traditional Sterlink internet satellites, which are 550 kilometers high, the study reports.
In January 2024, just a week after the first batch of six Starlink DTC satellites were placed into orbit, SpaceX used one to text messagesIn May, the company successfully demonstrated a video calland said it is working with T-Mobile to roll out such a mobile service to customers later this year. There are now more than 100 DTC satellites in low earth orbitincluding 13 that were launched last week. After successful testing of the first batch of DTCs, in March SpaceX an amendment requested their license with the U.S. Federal Communications Commission, which allows them to operate up to 7,500 DTCs in LEO.
At the time the study was conducted, SpaceX had not yet applied standard brightness reduction techniques to the DTCs, such as modifying the chassis and solar panels to reduce the portion of the spacecraft illuminated by the sun, lead researcher Anthony Mallama of the IAU Centre for the Protection of Dark and Quiet Skies from Satellite Constellation Interference (IAU-CPS) told Space.com.
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Kate Tice, senior manager for quality systems engineering at SpaceX, acknowledged during the January launch webcast that DTC satellites will be brighter than regular Starlinks, and said the company plans to work with astronomers to assess the impact on their observations before making any hardware adjustments that would dim the DTCs. SpaceNews reported.
SpaceX began applying brightness reduction techniques to regular Starlinks in 2020 after astronomers serious concerns expressed about the tracks of the satellites streaks across telescope imagesrendering them unusable. Before launch, the company now applies a mirrored dielectric surface to the bottom of each Starlink chassis to reflect sunlight into space rather than scattering it back Soil. After launch, the company will modify the spacecraft chassis and solar panels to further reduce the brightness. Together, these techniques are very effective, reducing the brightness of the Starlink satellites by a factor of 10, Mallama said.
If SpaceX applies these brightness-reducing techniques to the DTCs, which are nearly the same size as regular Starlinks, the DTCs would still be 2.6 times brighter than their traditional counterparts, Mallama and his colleagues reported in the recent researchwhich was internally reviewed by IAU-CPS and posted to the arXiv preprint server last month.
Although DTCs are brighter objects, they appear to move faster and spend more time in Earth’s shadow than regular Starlinks. This would offset some of their negative impact on astronomical observations, the study found.
“I see it more as a trade-off of parameters than an absolute better/worse kind of situation,” John Barentine, a principal consultant at Dark Sky Consulting in Arizona who was not involved in the new study, told Space.com.
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Barentine suspects that the radio emissions emitted by the DTC antennas, interfere with radio bands protected for astronomybecause the satellites communicate with the Earth via radio signals, but do not have a special spectrum available for this.
While scientists agree that providing connectivity to remote areas of the world is a noble goal, the rate at which satellites are being launched into orbit has many concerned — and not just because of their image-distorting brightness. million satellites may soon enter a space around Earth that is already filled with thousands of abandoned spacecraft, spent rocket bodies, and millions of millimeter-sized pieces of junk whizzing past us at high speed. This debris population poses a threat to satellites that provide internet services, navigation, and weather monitoring, and sometimes even to astronauts aboard the International Space Station.
Related: Astronomers urged to fight ‘tooth and nail’ to protect dark skies
Even if we can prevent a space disaster by responsibly deorbiting abandoned satellites, many scientists are concerned that the number of objects orbiting our planet could still be harmful: if deorbited, they could release a significant flux of metals that could alter the chemical composition of Earth’s atmosphere.
“Impacts on astronomy are just the tip of the iceberg,” said Barentine, who says we are rapidly approaching a tipping point where tragedy is imminent, either in space through a collision or on the ground through falling debris. “Space policymaking is far too slow to deal with this effectively.”
“There’s not much positive to look forward to right now,” he added. “If the New Space Age ends badly, history won’t look kindly on it.”