Tue. Sep 26th, 2023
SpaceX Implements New Mirror Film to Reduce Interference with Astronomy

When astronomers observe the sky, they may soon notice a decrease in the number of SpaceX satellites passing through their field of view. After facing complaints from scientists about the high reflectivity of its internet satellite constellation, SpaceX has introduced a new “mirror film” that redirects light away from Earth, potentially resolving Starlink’s impact on ground-based astronomy. However, currently, only a small number of the thousands of Starlink nodes have been coated with this new film.

Last week, SpaceX launched 22 new Starlink V2 satellites equipped with the mirror film for the first time. Video footage reveals the highly reflective dielectric mirror film covering the spacecraft. Interestingly, this mirror finish actually reduces visibility from the ground, contrary to what one might expect. SpaceX explains that the film, designed as a Bragg mirror or distributed Bragg reflector, consists of multiple layers of plastic with varying refractive indices, producing interference patterns that scatter light while allowing radio waves to pass through. Furthermore, SpaceX has also applied low-reflectivity black paint to certain parts of the satellites to absorb light.

Although astronomers are eager to see the results, they may need to exercise patience. With nearly 5,000 satellites planned, SpaceX has become the largest operator in low-Earth orbit. While Starlink satellites were designed to be affordable and easily replaceable, the more reflective versions will remain in orbit for years to come. Some existing satellites have been equipped with visors to minimize reflectivity, but this approach wasn’t entirely satisfactory due to increased atmospheric drag after deployment, as well as incomplete resolution of astronomical concerns.

SpaceX’s mirror film faces a significant test in the future when the physically larger V2 Starlink nodes are deployed using the upcoming Starship rocket. These larger satellites will be much more visible from the ground, serving as a clear indicator of the effectiveness of the mirror film. As other companies like Amazon plan their satellite megaconstellations, it remains uncertain whether they will prioritize reducing reflectivity or face similar criticism before taking action. This could mark the beginning of an ongoing struggle between the astronomical community and satellite operators.