LEO Reflectivity Seen as Increasingly Glaring Problem, but No Regulatory Fix

SpaceX will provide orbital characteristics data that AAS will use to model potential outcomes, said Jeff Hall, chairman of the AAS Committee on Light Pollution, Radio Interference and Space Debris. "We need to understand better the threat." Hall is also Lowell Observatory director.

There's "not much" the astronomy community can do aside from publicly raise the issue, emailed John Barentine, public policy director-International Dark of the Sky Association that fights light pollution. The current international regulatory framework is "just not well equipped" to handle deployment of satcom mega constellations, he said.

To avoid outcry, other LEO constellation operators are almost surely going to take into consideration their satellites' reflectivity, said Space Law and Policy Solutions principal Michael Listner. He said regulatory agencies like the FCC, however, likely won't take up the issue in their permitting reviews unless Congress adopts enabling legislation, and the astronomical community could lobby on Capitol Hill to make that happen. The FCC didn't comment Monday.

Potentially thousands of LEO satellites could go up in coming years, triggering such celestial viewing concerns. Hall said astronomical detection equipment is particularly sensitive, able to see items vastly fainter than what the human eye can, so the possibility of numerous items in the night sky raises "the potential for a severe impact." AAS said the part of the StarLink constellation already launched "shines as brightly as many astronomical constellations." "This goes well beyond astronomy," Hall said, since the satellites potentially could affect nighttime viewing without any equipment. The natural nighttime sky "is a resource ... for all of us," he said.

Hall said AAS hopes to have similar talks with other companies planning mega constellations. OneWeb didn't comment. Amazon said since it had just filed with the ITU, "it would be premature to get into specifics." It said its Project Kuiper project is years away from service, and many of its satellite and mission decision decisions "are, and will continue to be, driven by our goals of ensuring space safety and taking in to account concerns about light pollution."

SpaceX says it's in the early stages of raising its first batch of StarLink satellites to their intended orbit, which could take another three to four weeks. It says their orientation and visibility will change during that process. It's looking at ways of reducing the amount of light reflected on the side of the satellites facing the Earth's surface.

Iridium CEO Matt Desch said that 12,000 planned SpaceX satellites are "quite a bit different" from his company's 66 and the "flare" effect when one of them de-orbits. He said making StarLink satellites less shiny likely wouldn't be difficult or expensive. It's unclear why they're so reflective -- potentially because of the thermal blanket used -- "but that could be toned down," he emailed.

From an engineering standpoint, cutting down on reflectivity of satellites is not easy or cheap, said University at Buffalo mechanical and aerospace engineering professor John Crassidis. "It's a thermal nightmare" in orbit, he said. And reflectivity issues are likely going to be down the list of priorities behind such more pressing issues as orbital debris, he said.

Simply painting the satellites black or otherwise lowering the albedo is problematic because dark objects absorb heat from sunlight which they gets reradiated as infrared, which can affect the orbital parameters and even cause satellites to fall back to earth, Dark-Sky's Barentine said. Higher orbits would make them fainter but also require stronger radio transmitters on the ground and in space, which would create other potential interference problems, he said. "It's a vicious cycle."

Suing to try to enjoin more launches until some change to the satellites to reduce their reflectivity "very likely won't work" because of a lack of legal basis for a federal court to intervene or for a regulatory agency like the FCC to deny approval, Barentine said. "Protecting the night sky is not something recognized in law as a justification" for refusing permits, he said: As long as SpaceX and other LEO operators have the proper permitting, the U.S. is obligated to clear their launches. Barentine said there's no appetite in Congress to tackle such regulation, and even if it did, getting it passed would likely take years. Barentine said the other option is working with commercial space companies voluntarily to limit the problem.