As SpaceX’s Starlink Rises, Light Pollution Could Also


“It’s going to be difficult to compete with SpaceX in this area, given its obvious advantage at launch. Competitors do exist and are forming, however, which suggests that the market still sees opportunities, ”Matthew Weinzierl, a Harvard Business School economist who studies space industry commercialization, wrote in an email to WIRED.

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

But an Amazon representative said the company is aware of potential light pollution issues. “Reflectivity is a key consideration in our design and development process. We have already made a number of design and operational decisions that will help reduce our impact on astronomical observations, and we are engaging with community members to better understand their concerns and identify actions we can take, ”a writes the spokesperson by e-mail. .

“and to create design and operating practices that support both communities. We are also undertaking light measurements and will be examining these results to explore solutions.”

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

Earlier last year, SpaceX tested a Starlink satellite dubbed Darksat, giving it an experimental darkening coating on one side, including the antennas, to reduce reflective brightness, which the company says has been reduced by 55%. . In a paper, some astronomers have found that the measurement darkens the satellite but not to this degree, although it makes the satellite invisible to the naked eye. Others did not detect any significant obscuration at all. They found that the measured brightness of the satellite can vary, however, depending on the angle at which it is viewed and how the light diffuses through the atmosphere.

According to a publish on the company website, SpaceX discovered that dark surfaces get hot, endangering satellite components, and that it always reflects light in the infrared. So the company later tested a different approach it calls Visorsat, deploying a number of satellites with rectangular sunshades attached, like the one used on a car windshield. These visors are intended to ensure that sunlight bouncing off satellite antennas is reflected away from the Earth.

So far, SpaceX has not released any information on how this approach works or how it compares to Darksat. Corn another astronomer, in an unpublished article published on the university preprint server arXiv.org, and Boley’s work-in-progress team, both independently discovered that at least 70% of Visorsat spacecraft were even brighter than their threshold preferred: a level that would ensure that the images in the Vera C. Rubin Observatory are hardly affected.

To draw attention to light pollution problems and to work on developing solutions, the American Astronomical Society hosted a virtual workshop on satellite constellations this summer, known as the SatCon2. They plan to issue reports and recommendations soon, coinciding with a meeting starting this Sunday, titled “Dark and calm skies for science and society», Organized by the United Nations and the International Astronomical Union.

Video: Google

The organizers of SatCon2 have made it a priority to reach a wide range of people concerned with the night sky, including amateur astronomers, astrophotographers, the planetarium community, environmentalists, and indigenous and tribal communities in the United States, Canada. , New Zealand and other countries. . “Everyone wanted things to slow down. They want the industry to be more engaged. It’s something that everyone owns as a global common good, ”says Amina Venkatesan, astrophysicist at the University of San Francisco and SatCon2’s public engagement co-chair.

As part of SatCon2, a task force of astronomers spoke with representatives from SpaceX and five other major satellite operators about the limits of reflected light proposed by researchers and how companies could assess and reduce the degree of reflection of their spacecraft. They also debated policy options in the United States that could involve making rules about how much light pollution Internet satellites can create. These include the possibility of regulations imposed by the Federal Aviation Administration, which sets the conditions for launch and re-entry, or the FCC, which allows radio frequencies in orbit. Some astronomers would also like the National Environmental Policy Act to end its exemption for space, meaning that they see space as an environment to be protected.

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