NSF And SpaceX Astronomy Coordination Agreement

SpaceX is launching and operating its satellite constellation in low-Earth orbit to provide high-speed internet service.

SpaceX’s satellite network currently provides high-speed internet to more than 600,000 locations in the United States, often in remote or previously unserved and underserved areas. Some of the frequencies in which the satellites transmit towards Earth are adjacent to radio astronomy allocations. Operating the satellites without mitigations could impact ground-based radio, optical and infrared astronomy facilities.

SpaceX worked with the U.S. National Science Foundation and its radio astronomy observatories to mitigate potential interference from SpaceX satellite transmissions, focusing on the 10.6 – 10.7 GHz radio astronomy band. NSF and SpaceX finalized a coordination agreement in 2019 to ensure the company’s Starlink satellite network meets international radio astronomy protection standards for that band. This also fulfilled conditions of their Generation 1 Federal Communications Commission license (File No. SAT-MOD-20200417- 00037).

NSF and SpaceX continue to explore methods to further protect ground-based astronomy, and a new coordination agreement was signed in 2022 with the following provisions, which fulfilled conditions of their Generation 2 FCC license (File No. SAT-AMD-20210818-00105):

NSF and SpaceX agreed to cooperate to the extent practicable to mitigate the impact on optical and infrared ground-based astronomical facilities. SpaceX committed to continue work towards recommendations that came from NSF’s NOIRLab, the American Astronomical Society’s SATCON workshops and the International Astronomical Union’s Dark and Quiet Skies best practices guidance. These recommendations include continuing to work to reduce the optical brightness of their satellites to 7th visual magnitude or fainter by physical design changes, attitude maneuvering, or other ideas to be developed; maintaining orbital elevations at ~700 km or lower; and providing orbital information publicly that astronomers can use for scheduling observations around satellite locations.

Specific mitigations SpaceX has developed for its second-generation satellites include dielectric mirror film, solar array mitigations, new black paint that minimizes brightness and glints, and best practices during flight operations. Details of these mitigations and ongoing work were presented at the 2022 Vera C. Rubin Community Workshop.

SpaceX agreed to analyze the impact of astronomical facility lasers on its satellites. Following this analysis, the Laser Clearinghouse removed the coordination requirements for these lasers. Therefore, adaptive optics lasers at ground-based facilities will no longer undergo multiple closures every time the SpaceX satellites pass nearby. SpaceX is also working with NSF’s NOIRLab to organize a workshop to develop best practices guidance on these topics. The workshop will recommend processes for interactions between satellite operators and the Laser Clearinghouse aimed at mitigating negative impacts on ground-based astronomical facilities.

For radio astronomy, SpaceX committed to coordinating dynamically with impacted United States radio astronomy facilities. This commitment goes beyond the required international protections for the 10.6-10.7 GHz band and enables radio astronomy observations operating in other bands that are not allocated to radio astronomy. This coordination includes avoiding main beam illumination during observations at key radio astronomy facilities that would be impacted, such as the Very Large Array (VLA), Very Long Baseline Array (VLBA), Green Bank Observatory (GBO), Arecibo Observatory (AO), and geodetic Very Long Baseline Interferometric (VLBI) stations.

SpaceX and NSF’s National Radio Astronomy Observatory (NRAO) completed field tests at the VLA and GBO and have more tests planned in the coming year to verify that radio astronomy observations are not impacted. Additionally, due to the high demand for satellite internet in communities that have been historically underserved or unserved, some of which are located near radio astronomy observatories, NSF’s NRAO has initiated a pilot program to test the impact of SpaceX user terminals in close proximity to the VLA.

SpaceX committed to coordinating with NSF’s Office of Polar Programs to work to minimize the impact of SpaceX on remote geographical radio astronomy sites in polar regions when the SpaceX constellation provides data connectivity in these regions.

NSF’s NOIRLab serves as the key point of contact for technical exchanges with SpaceX on optical and infrared issues and NSF’s NRAO for radio astronomy issues. NSF is grateful for the work of NOIRLab staff Julian Christou, Pat McCarthy and Connie Walker and NRAO staff Tony Beasley, Chris De Pree and Harvey Liszt and many other colleagues.

SpaceX committed to work with NSF as interference arises or new challenges are brought to our attention by the astronomy community. Regulatory agencies should set a high standard for new and existing satellite systems to implement spectrally efficient methods that expand the scope of scientific missions by NSF and its facilities, not reduce them.

NSF and SpaceX have collaborated from the beginning on how best to meet the goals of protecting astronomy while also providing maximum internet access for communities across the United States. The mitigation steps taken can and should serve as a model for coordination among satellite operators and the astronomy community within the United States and beyond.
“We are setting the stage for a successful partnership between commercial and public endeavors that allows important science research to flourish alongside satellite communication,” said NSF Director Sethuraman Panchanathan.