Astronomers rely on clear skies and undisturbed frequencies to explore the universe. But as satellite technology grows, so does the potential for interference with these sensitive observations. A new collaboration between the U.S. National Science Foundation’s National Radio Astronomy Observatory (NSF NRAO) and SpaceX demonstrates how radio astronomers and satellite internet providers can effectively share access to the sky.
The NSF NRAO oversees some of the world’s most critical radio telescopes, positioned in remote areas like the Appalachian Mountains and New Mexico’s high plains to minimize interference. Meanwhile, SpaceX’s Starlink network has revolutionized internet access, bringing connectivity to even the most isolated regions.
However, the same satellites that offer this connectivity can interfere with the faint cosmic signals these telescopes aim to detect. To address this challenge, NSF NRAO and SpaceX are working together to balance the need for internet access with the preservation of astronomical observations.
SpaceX began collaborating with the NSF and its observatories in 2019, signing an agreement to explore methods for sharing the sky. Since then, ongoing experiments and updates to this agreement have expanded the protection of radio astronomy frequencies beyond the levels required by international regulations. This includes dynamic coordination between Starlink and key NSF instruments, such as the Very Large Array (VLA), the Very Long Baseline Array (VLBA), the Green Bank Observatory (GBO), and other geodetic Very Long Baseline Interferometric (VLBI) stations.
In the National Radio Quiet Zone (NRQZ)-a specially regulated area that protects sensitive radio observations at the NSF Green Bank Observatory and other federal facilities-SpaceX will soon offer Starlink access without significantly disrupting astronomical research. Through a method called Telescope Boresight Avoidance, the collaboration allows nearly all residents of the NRQZ to access either fixed or mobile Starlink services while minimizing interference with critical scientific studies.
Telescope Boresight Avoidance is one of two significant advances in this partnership. This technique, combined with an autonomous system known as the Operational Data Sharing (ODS) framework developed by NRAO, allows Starlink satellites to avoid interfering with ongoing telescope observations. ODS provides real-time data to Starlink satellites about the telescopes’ current focus, including direction, frequency, and bandwidth, enabling the satellites to adjust their transmissions accordingly.
“While we are still testing the system, this is a major achievement, and a clear example of the benefits of regular communication and experimentation involving active and passive users of the radio spectrum,” commented De Pree.
Ashley VanderLey, a senior advisor at NSF, emphasized the broader significance of this work: “This work is the culmination of years of ongoing commitment to scientific discovery by the satellite industry, together with years of Federal investment under the U.S. NSF Spectrum Innovation Initiative, and is an excellent example of the dynamic spectrum sharing called for in the U.S. government’s National Spectrum Strategy.”
The NSF NRAO hopes that the Telescope Boresight Avoidance method will help reduce the impact of Starlink and other satellite constellations on radio telescopes across the U.S. and potentially worldwide. The first scientific paper detailing these systems and experiments has been accepted for publication in the Astrophysical Journal Letters.
“We hope ODS will provide a framework for other radio observatories and satellite constellations to share the skies, and work side-by-side in the coming decades,” added Bang Nhan, lead author and NSF NRAO Assistant Scientist in Spectrum Management.
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