As SpaceX’s Starlink ramps up, it can ease pollution

“It will be difficult to compete with SpaceX in this domain, given its obvious advantage at launch. However, competitors exist and are being formed, 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 rejected interview requests from WIRED.

However, a representative from Amazon stated that the company is aware of potential problems with light pollution. “Reflection is an important factor in our design and development process. “We have already made a number of design and operational decisions to help reduce our impact on astronomical observations, and we are working with members of the community to better understand their concerns and identify steps we can take,” the spokesman wrote in an email. .

Katie Dowd, director of government and business at OneWeb in North America, wrote in an email to WIRED that the company is talking to 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 also conduct light measurements and will look at these results to examine solutions.”

SpaceX and its competitors cannot avoid light pollution; they can only reduce it. Each object in the atmosphere reflects at least some light during part of its orbit, depending on its materials, color, and size. While satellites radiate information down to Earth, a little bit of sunlight is often reflected down as well, both by a satellite’s body and its solar system.

Early last year, SpaceX tested a Starlink satellite nicknamed Darksat, giving it an experimental darker coating on one side, including antennas, to reduce the reflective brightness that the company claims was reduced by 55 percent. In a paper, some astronomers found that the measure made the satellite darker, but not to the extent that it made the satellite invisible to the naked eye. Others did not detect significant darkening at all. However, they found that the measured brightness of the satellite may vary depending on the angle at which it is observed and how the light is scattered throughout the atmosphere.

According to a post on the company’s website, SpaceX found that the dark surfaces were getting hot, endangering the satellite’s components, and that it was still reflecting light in infrared. So the company later tested another approach, which it calls Visorsat, and implements a number of satellites with attached rectangular sunshades, such as the one used on a car windshield. These visors are designed to ensure that sunlight bouncing off the satellites’ antennas is reflected away from Earth.

So far, SpaceX has not publicly released information on how well this approach works or how it compares to Darksat. But another astronomer, in an unpublished paper posted on the academic pre-print server, and Boley’s team in ongoing work, both independently find that at least 70 percent of the Visorsat spacecraft was still brighter than their preferred threshold: a level it would ensure that the Vera C. Rubin Observatory’s images will be mostly unaffected.

To raise awareness of light pollution concerns and work to develop solutions, this summer the American Astronomical Society convened a virtual workshop on satellite constellations, known as SatCon2. They plan to soon release reports and recommendations that coincide with a meeting beginning this Sunday called “Dark and Quiet Skies for Science and Society,” organized by the United Nations and the International Astronomical Union.

Video: Google

SatCon2 organizers prioritized reaching out to a wide range of people concerned about the night sky, including amateur astronomers, astrophotographers, the planetary community, environmentalists, and indigenous and tribal communities from the United States, Canada, New Zealand, and other countries. “Everyone wanted things to slow down. They want the industry to get more involved. This is something that belongs to everyone as a global commons, ”says Amina Venkatesan, an astrophysicist at the University of San Francisco and SatCon2 co-chair of public engagement.

As part of SatCon2, a working group of astronomers with representatives from SpaceX and five other major satellite operators talked about what reflected light limits scientists propose and how companies could assess and reduce how reflective their spacecraft is. They also discussed policy options in the United States that could involve setting rules for how much light pollution Internet satellites can create. These include the possibility of regulations imposed by the Federal Aviation Administration setting conditions for launch and re-entry, or the FCC licensing radio frequencies in orbit. Some astronomers would also like to see the National Environmental Policy Act end its exemption from space – that is, they see space as an environment in need of protection.

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