Mega Constellations Acting to Address Astronomy's Light Pollution Worries
About 350 SpaceX satellites are in orbit with deployable visors to reduce the reflective light pollution they give off, and Amazon's Kuiper is taking astronomy concerns into consideration in its plans, in design stage for its low earth orbit (LEO) mega constellation. That's according to satellite operators Monday in a Satellite Industry Association/American Astronomical Society virtual panel about an AAS/National Science Foundation report released in August on some possible mitigations (see 2010020036). Jeff Hall, chairman of the AAS Committee on Light Pollution, Radio Interference and Space Debris, said a second report with more policy focus is being planned.
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The visors "have real promise" as a mitigation approach, said Patricia Cooper, SpaceX vice president-satellite government affairs. She said SpaceX aims to change angles of its Starlink broadband satellites during orbit raising and parking so they're not visible to the naked eye. She said there must be a more efficient, streamlined route of constellation operators engaging with astronomers. The satellite industry also needs to consider simulating and testing for brightness issues prior to launching satellites, she said.
Now not tied up with its Chapter 11 bankruptcy, OneWeb will be more engaged on the astronomy issue, said Maurizio Vanotti, its technology, strategy and partnerships head. He said it plans to resume launches in December, and fully deploy the first generation of its broadband constellation before the end of 2022. Vanotti also indicated OneWeb’s stated plans for a 47,000-satellite second generation (see 2005270010) likely will be scaled back, noting its first-generation plans were initially for 2,000 and eventually became 650. He said the 47,000 number is being reviewed.
OneWeb is looking for "some quick wins" on cutting down brightness, such as addressing the reflectivity of some surfaces, Vanotti said. But dramatic changes to its assembly process are "extremely difficult, if not impossible," he said.
Astronomy interests urged constellations to avoid orbits much higher than 600 kilometers. Large Synoptic Survey Telescope Chief Scientist Tony Tyson said at that height, satellites are shielded for much of the night from the sun's rays, but higher, such as at 1,200 kilometers, they can be seen all night. "There's no place to hide, no dark sky ever," he said.
Design-based recommendations such as darkening satellites or using fewer of them have mission operations and space safety implications that could have adverse effects, said Kuiper Global Regulatory Affairs Head Julie Zoller. Lower altitudes mean more satellites must be deployed, she said.
Aerospace Corp. is trying to make it an industry norm for LEO constellations to have GPS coordinates of their satellites readily available, so astronomers can know in advance what's going to be in their line of sight and account for that, said Senior Project Leader-Space Traffic Management (STM) Mark Skinner. That, plus use of visors, "won't be any silver bullet" but could have demonstrable effects on tackling light pollution issues. He said the open architecture data repository of the Commerce Department in its STM role also could be a good resource for exchanging information.