NSF's ongoing technical coordination with satellite constellation operators

Since 2019, the U.S. National Science Foundation has conducted extensive technical coordination work with operators of satellite constellations in low Earth orbit to reduce negative impacts on ground-based radio, optical and infrared astronomy facilities.

Building on earlier satellite coordination work, NSF has established a new coordination agreement with AST SpaceMobile to collaborate with NSF facilities and the U.S. astronomical community to mitigate the impacts of AST SpaceMobile's satellites on ground-based astronomy facilities.

AST SpaceMobile has partnered with AT&T to provide a space-based cellular broadband network in low Earth orbit. The coordination between NSF and AST SpaceMobile builds on the longstanding collaboration between the NSF Green Bank Observatory and AT&T through the specially engineered low-power antenna system in use at the Snowshoe Mountain Ski Resort in West Virginia that provides cell coverage while avoiding interference with the observatory's scientific mission.

The new agreement includes the following key areas of coordination between NSF and AST SpaceMobile:

• Taking steps to mitigate potential interference from AST SpaceMobile's large, phased array satellites and other impacts of such satellites, including direct-to-cell downlink interference with ground-based radio astronomy facilities.
• Working to achieve recommendations in the International Astronomical Union's Dark and Quiet Skies best practice guidance, including reducing the optical brightness of satellites through physical design changes, attitude maneuvering and other methods, maintaining orbital elevations at 700 km or lower, and providing high-precision orbital information that astronomers can use to schedule observations that avoid satellite locations. The coordination work is also supported by NSF through an August 2024 award to NSF NOIRLab to develop publicly accessible software tools and online services astronomers can use to predict the satellite positions, time of passage and brightness.
• Analysis of the impact of lasers used by astronomy facilities on AST SpaceMobile's satellites. Depending on the analysis, AST SpaceMobile will consider removing its satellites from the U.S Department of Defense Laser Clearinghouse coordination system.
• Collaboration with the NSF National Radio Astronomy Observatory (NSF NRAO) to ensure that future direct-to-cell satellite downlinks and gateways do not cause harmful interference or damage to radio astronomy receivers. AST SpaceMobile, NSF and NSF NRAO will conduct field tests to fully characterize the effects and what mitigation restrictions are needed.
• Collaboration with the NSF Office of Polar Programs to minimize the impact of satellites on radio astronomy sites in polar regions if AST SpaceMobile satellites provide service in those regions in the future.

"NSF is working with commercial satellite companies to help ensure continued U.S. leadership in the scientific exploration of the universe," says Chris Smith, interim director of the NSF Division of Astronomical Sciences. "We also want to sustain the significant economic benefits and jobs that are created by NSF's observatories in the many states and communities that host them."

Members of the U.S. astronomical sciences community can contact the NSF Electromagnetic Spectrum Management group for technical questions and information on how observatories can participate in this work.