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SpaceX is testing ways to stop Starlink from showing up in space images of its satellites, working to minimize the satellites to astronomers. The company recently lowered the altitude of a batch of its Internet satellites to reduce their brightness as seen from Earth.
A the letter To the Federal Communications Commission (FCC), SpaceX disclosed that SpaceX has begun operating 300 of its satellites at low orbital altitudes as part of the company’s efforts to reduce Starlink’s impact on optical astronomy. The company claims the new method has been successful, resulting in a nearly 60% reduction in sun-lit satellites in images captured by the Vera Rubin Observatory, a telescope in Chile.
Low Earth orbit is increasingly populated by satellites, most of which belong to SpaceX. There are currently 6,912 Starlink satellites in orbit, located approximately 342 miles (550 kilometers) above Earth’s surface. Orbiting satellites reflect sunlight, adding unwanted noise to observations of the night sky, appearing as streaks in images captured by ground-based observatories. The first Starlink satellites were very bright, making them visible to the unaided eye and filling the lenses of telescopes pointed at them.
In December 2022, the FCC approved SpaceX to launch up to 7,500 Next generation Starlink satelliteswhich are bigger and brighter than their predecessors. The first-generation Starlinks weighed about 573 pounds (260 kilograms), but future versions are much larger at 2,755 pounds (1,250 kg) and are therefore estimated to be about 100 pounds heavier than the OG satellites. Full brightness.
SpaceX is collaborating with the National Science Foundation (NSF) to reduce the impact of its next-generation satellites on optical astronomy. The company recently lowered the altitude of its demo Starlinks to 217 miles (350 km) above Earth’s surface, reducing their ability to capture and reflect sunlight.
SpaceX’s analysis also shows that peak brightness from the nadir surface increases slightly when operating at 350 km. [217 miles]”due to a high eclipse fraction and angular rate,” the company wrote in its letter. In other words, SpaceX says that the reflected brightness of satellites, as seen from directly below, does not increase much at low altitudes because they spend more time in Earth’s shadow and across the sky. move fast
NSF agrees that this strategy can help. Low orbits “can be beneficial for ground-based optical and infrared astronomy because satellites move quickly through a telescope’s focal plane and are out of focus, reducing the overall brightness per pixel,” an NSF spokesperson told Gizmodo in an email. “At lower altitudes, satellites are also blocked from sunlight by the Earth for long parts of the night, not reflecting back to the ground.” This allows the satellites to remain dimmer than about 7th magnitude – the threshold for visibility with the naked eye – for most of the night, the spokesperson explained.
Previous efforts have been made to minimize Starlink’s impact on astronomical observations. SpaceX is working with the International Astronomical Union, and its Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference, to find the main source of its satellite reflections and develop strategies to mitigate them. As a result, the company changed the orientation of the satellites and their solar panels and installed visors to reduce their brightness.
This recent change in the orbit of the satellites is still being evaluated as it may contain some errors. “There is a trade-off, satellites at lower altitudes can be brighter in twilight and affect science that requires twilight observations, such as surveys of near-Earth objects,” NSF added. The foundation will continue to work with SpaceX over the next year to verify that mitigation is working as intended.
It’s not just SpaceX launching satellites into orbit, and the growing amount of cluttered hardware in Earth orbit could further obscure our view of the cosmos unless more companies commit to reducing their interference in astronomy.
