Starlink Already Threatens Optical Astronomy. Now, Radio Astronomers are Worried
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Starlink already threatens optical astronomy. Now, radio astronomers are worried:
The 197 radio astronomy dishes of the Square Kilometre Array (SKA) in South Africa will sit within a radio-quiet zone the size of Pennsylvania where even a cellphone is forbidden, to preserve the array's views of the heavens. Yet that precaution won't save the telescope, due to be completed in the late 2020s, from what may soon be overhead: tens of thousands of communications satellites beaming down radio signals straight from the heavens. "The sky will be full of these things," says SKA Director General Phil Diamond.
[...] So far, SpaceX has launched more than 700 Starlinks out of an initial goal of 1440, and it has won approval for 12,000. Other operators, such as OneWeb and Amazon's Project Kuiper, have similar ambitions. Studies suggest wide-field optical surveys will be worst affected, with satellite tracks marring most images. The team building the Vera C. Rubin Observatory, a survey telescope in Chile due to see first light next year, has been working with SpaceX to reduce the impact. The company has changed the orientation of satellites as they move up to their final orbit, painted them a less reflective color, and fitted "visors" to reduce reflections. Since August, all launched Starlink satellites have visors, SpaceX's Patricia Cooper, vice president for satellite government affairs, told the UNOOSA workshop this week. "We're trying to look for a path where we can coexist," she said.
[...] The [SKA] team calculated that satellite transmissions will lead to a 70% loss in sensitivity in the downlink band. If the number of satellites in megaconstellations reaches 100,000, as predicted by many, the entire band 5b would be unusable. SKA would lose its sensitivity to molecules such as the simplest amino acid, glycine, a component of DNA. "If it was detected in a planetary system that was forming, that would be a very interesting piece of information," Diamond says. "This is a new area that SKA is opening up." The band could also contain the fingerprints of water molecules in distant galaxies, a tracer that cosmologists use to study how dark energy is accelerating the expansion of the universe.
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