NRAO Considers Spreading Success of Collaboration With SpaceX on RF Mitigation
The National Radio Astronomy Observatory and SpaceX are assessing how to limit RF interference coming from Starlink satellites that causes issues with the Very Large Array (VLA) observatory in New Mexico, according to NRAO Deputy Spectrum Manager Chris De Pree. In addition, NRAO is considering implementing those methods with its additional telescopes and sharing successes with other U.S. observatories.
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Radio observatories can handle many of the interference challenges that come from low earth orbit (LEO) satellites in the Ku and X bands, but the terrestrial bands used by direct-to-device (D2D) service are a different matter, De Pree said during a Broadband Breakfast panel Wednesday.
FCC Space Bureau Chief Jay Schwarz said the bureau's near-term priorities include modernizing its licensing system to increase speed, predictability and flexibility. Getting FCC approval shouldn't be "a multiyear odyssey," and the bureau's rules and processes need more flexibility concerning new approaches and ideas, he said: "Our rules are written for an old world."
In addition, Schwarz said the bureau wants to ensure spectrum availability for space operations, which would mean looking at new bands and determining if existing bands are used to their full potential. The bureau will also try to determine if there are outdated technical rules that prevent the best and highest use of spectrum.
Radio astronomers built telescopes like VLA in rural, remote venues to shield them from radio interference, De Pree said. The assumption was always that RF interference would come from sources along the horizon. But the proliferation of LEOs puts RF interference sources in the sky, often in the line of sight of where radio telescopes are pointing, he said.
NRAO and SpaceX have tried operational data sharing -- real-time sharing of data about where NRAO's telescopes are pointing, their frequency and bandwidth -- so SpaceX can conduct "zone avoidance" maneuvers, De Pree said. The two also have worked on SpaceX deactivating downlink beams when they would cause the most interference to VLA. SpaceX has a highly redundant satellite system, so quieting a beam to avoid interference with a radio observatory doesn't materially affect its service, De Pree said.
Radio observatories can adapt to SpaceX's use of the 10.7-12.7 GHz band for its broadband downlinks, but the bands for its D2D service are a bigger challenge. De Pree said that as the D2D market grows, the interference challenges it poses increase. Should a limited number of terrestrial mobile bands get used for D2D, radio astronomy can respond; however, it can't avoid all bands used for mobile.
Noting ITU meetings this week in Switzerland, De Pree said NRAO is trying to get telescope avoidance matters before the international community by describing some of the techniques it's using. The international community must address RF interference since satellite orbits are inherently global.
Peter Davidson, Intelsat's vice president-global government affairs and policy, said the anticipated global boom in LEOs during the next five to 10 years foreshadows issues ranging from RF interference to collision risks and space junk.
Satellite Industry Association Policy Director Madeleine Chang also noted a concern about the lack of a simple way for U.S. satellite operators to communicate with their Chinese counterparts in the event of a collision.