As SpaceX’s Starlink Ramps Up, So Could Light Pollution

Other industry players, who generally stick to one or the other of these ranges of orbit altitudes, include the UK’s OneWeb and planned satellite constellations like Amazon’s Project Kuiper, China’s Starnet/GW, and Canada’s Telesat. But Starlink’s constellation will likely remain the biggest one, at least for a while: SpaceX has already shipped terminals, which include a Wi-Fi router and satellite dish, to beta users in 14 countries, mainly in Western Europe and North America, including rural and remote users, according to Musk’s tweets, and the company plans to expand the user base to at least half a million

“It’s going to be difficult to compete against SpaceX in this domain, given its obvious advantage in launch. Competitors exist and are being formed, however, suggesting that the market still sees opportunity,” wrote Matthew Weinzierl, an economist at Harvard Business School who researches the commercialization of the space sector, in an email to WIRED.

A representative from SpaceX’s communications team declined interview requests from WIRED.

But a representative from Amazon indicated the company is aware of potential light pollution issues. “Reflectivity is a key consideration in our design and development process. We’ve already made a number of design and operational decisions that will help reduce our impact on astronomical observations, and we’re engaging with members of the community to better understand their concerns and identify steps we can take,” the spokesperson wrote by email.

Katie Dowd, OneWeb’s director of government and corporate affairs in North America, wrote in an email to WIRED that the company is talking with groups, including the UK’s Royal Astronomical Society and the American Astronomical Society, to understand the effects satellites have on observations, “and to create design and operational practices that support both communities. We are also undertaking brightness measurements and will be looking at those results to explore solutions.”

SpaceX and its rivals can’t avoid light pollution; they can only reduce it. Every object in the atmosphere reflects at least some light during part of its orbit, depending on its materials, color, and size. While satellites beam information down to Earth, a tiny bit of sunlight often gets reflected down, too, both by a satellite’s body and its solar array.

Early last year, SpaceX tested a Starlink satellite nicknamed Darksat, giving it an experimental darkening coating on one side, including the antennas, to cut down on the reflective brightness, which the company claims was reduced by 55 percent. In one paper, some astronomers found that the measure did darken the satellite but not to that degree, though it made the satellite invisible to the naked eye. Others didn’t detect significant darkening at all. They found that the satellite’s measured brightness may vary, however, depending on the angle at which it’s observed and how the light scatters through the atmosphere. 

According to a post on the company’s website, SpaceX found that the dark surfaces got hot, putting the satellite’s components at risk, and that it still reflected light in the infrared. So the company later tested a different approach that it calls Visorsat, deploying a number of satellites with rectangular sun shades attached, like the one used on a car windshield. Those visors are intended to make sure that sunlight that bounces off the satellites’ antennas is reflected away from Earth. 

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