Washington, D.C., August 26, 2025
In the Matter of Satellite Spectrum Abundance Expanding Use of the 12.7-13.25 GHz Band for Mobile Broadband or Other Expanded Use Shared Use of the 42-42.5 GHz Band Use of Spectrum Bands Above 24 GHz For Mobile Radio Services
SB Docket No. 25-180, GN Docket No. 22-352, WT Docket No. 23-158, GN Docket No. 14-177
The American Astronomical Society (AAS) appreciates the opportunity to provide reply comments on the above proceedings seeking to make additional spectrum resources available for Fixed-Satellite Service (FSS) communications, including select frequency bands ranging from 12.7 to 114.25 GHz.
AAS fully endorses the comments on these proceedings from the National Radio Astronomy Observatory (NRAO) [1] and the National Academies’ Committee on Radio Frequencies (NAS CORF) [2], along with those of other scientific societies including the American Geophysical Union (AGU), American Meteorological Society (AMS), National Weather Association (NWA) and University Corporation for Atmospheric Research (UCAR) [3], as well as the Institute for Electrical and Electronics Engineers (IEEE) Geoscience and Remote Sensing Society (GRSS) [4]. Many of the frequency bands under consideration for repurposing in these proceedings are shared as co-primary by the Radio Astronomy Service (RAS) and passive Earth Exploration-Satellite Service (EESS); we provide the same table of relevant RAS bands and applicable US footnotes submitted with our previous comments as a reference in the attached Annex.
While a number of comments from the satellite industry support making the 42 GHz band available for satellite use [5-11], our initial comments and those of NRAO and NAS CORF explained that allowing such use of the band will significantly impact radio astronomy operations. We recommend that the Federal Communications Commission (FCC, “The Commission”) employ Recommendations ITU-R RA.769-2 and ITU-R RA.1513-2, which define protection criteria for RAS systems from various sources of harmful interference (both terrestrial and space-based), as guidance especially for the 42.5–43.5 GHz RAS primary allocation that is adjacent to the 40.5–42.5 GHz band considered for repurposing under these proceedings.
Furthermore, the W-band frequencies considered for repurposing (92–114.25 GHz) are currently subject to active study under agenda item (AI) 1.18 of the 2027 World Radiocommunication Conference (WRC-27), titled “Studies on compatibility between the Earth exploration-satellite service (passive), the radio astronomy service in certain bands above 76 GHz, and active services in adjacent and nearby frequency bands.” [12] Allowing FSS use of the W-band under these proceedings would necessitate a significant broadening of the scope of WRC-27 AI 1.18 and additional studies to account for the new active services operating within or adjacent to RAS and EESS allocations. We additionally wish to draw attention to internationally established Power Flux Density (PFD) and Equivalent Power Flux Density (EPFD) limits, which serve to prevent harmful interference between various services, including satellite and terrestrial systems. Continued strict adherence to these international rules should be upheld.
We share the concern expressed in a number of comments to both these proceedings and the “Modernizing Spectrum Sharing” NPRM (FCC 25-29), that allowing the operations considered under each would place United States spectrum management in conflict with the rest of the world. This is especially concerning given the inherently international nature of radio astronomy, with major US-funded facilities like the Atacama Large Millimeter/submillimeter Array (ALMA) being sited in Chile due to geographic advantages that maximize observation quality. The International Telecommunication Union Radio Regulations (ITU RR) are based on rigorous study using consensus-agreed standards recognized across international borders; departing from this framework does not encourage efficiency and consistency, which is a goal of effective regulatory systems. Ignoring the Table of Frequency Allocations at the request of a single applicant also sets a strong, yet troubling precedent, either demonstrating that certain entities have special spectrum privileges, or effectively making spectrum use across services a free-for-all.
We reiterate from our previously submitted comments that the locations of scientific spectrum bands are determined by physics, not by convenience, and because of that fact our allocations cannot be relocated. [13] Radio astronomy not only expands the bounds of human knowledge, but also enables critical services like GPS and drives innovation at the bleeding edge of spectrum technology. Remote sensing sciences monitor weather, climate, and ocean data critical to predicting natural disasters and protecting human life and property. The value of a radiocommunication service should not be measured in profit alone.
It is in the Commission’s mandate to make decisions based on “public interest, convenience and necessity,” [14] and the public interest cannot be served by selective prioritization of services. The FCC Space Bureau has historically recognized the importance of passive services in advancing the public interest, and acted on this recognition by incorporating requirements for coordination with the U.S. National Science Foundation (NSF) into its satellite network licensing process. This coordination has fostered positive relationships between academia and industry and produced innovative methods for satellite-astronomy coexistence, including an Operational Data Sharing (ODS) framework15 that recently enabled expansion of broadband access to over 99.5% of residents in the National Radio Quiet Zone surrounding the NSF-funded Green Bank Observatory in West Virginia. [16] Following proper planning and good faith coordination, FSS operations expanded to reach new customers while protecting scientific research. The United States can use this successful example to promote ODS adoption globally to the benefit of U.S. satellite operators.
We urge the Commission to carefully consider the potential repercussions of allowing the disruptive operations proposed under these proceedings and “Modernizing Spectrum Sharing” FCC 25-29, and whether more careful examination could identify opportunities for FSS operators that do not threaten multiple incumbent services, active studies on WRC-27 AIs, and the internationally adopted spectrum regulatory framework.
On behalf of the American Astronomical Society,
Dara Norman, PhD
President, American Astronomical Society
1. Comments of the National Radio Astronomy Observatory and Green Bank Observatory: https://www.fcc.gov/ecfs/document/107261780714801/1
2. Comments of the National Academy of Sciences’ Committee on Radio Frequencies: https://www.fcc.gov/ecfs/document/1072852368008/1
3. Comments of the American Geophysical Union, American Meteorological Society, National Weather Association and University Corporation for Atmospheric Research: https://www.fcc.gov/ecfs/document/10728088696934/1
4. Comments of the IEEE Geoscience and Remote Sensing Society (IEEE GRSS): https://www.fcc.gov/ecfs/document/107312540421754/1
5. Comments of The Satellite Industry Association: https://www.fcc.gov/ecfs/document/107280764926835/1
6. Comments of Kuiper Systems LLC: https://www.fcc.gov/ecfs/document/10728169819980/1
7. Comments of Space Exploration Holdings, LLC: https://www.fcc.gov/ecfs/document/107290555708199/1
8. Joint Comments of the Satellite Operators SES S.A., Uetelsat S.A., Hispasat, S.A., and Ovzon LLC: https://www.fcc.gov/ecfs/document/10729692629902/1
9. Comments of Logos Space Service, Inc: https://www.fcc.gov/ecfs/document/1072870379554/1
10. Comments of AST & Science, LLC: https://www.fcc.gov/ecfs/document/10728294216067/1
11. Comments of Open Technology Institute at New America and Public Knowledge: https://www.fcc.gov/ecfs/document/10729884309139/1
12. ITU-R Resolution 712 (WRC-23)
13. For additional information, see “The Spectrum Needs of U.S. Space-Based Operations: An Inventory of Current and Projected Uses,” National Telecommunications and Information Administration, Office of Spectrum Management (July 2021) at 13-18, 32-35: https://www.ntia.gov/report/2021/spectrum-needs-us-space-based-operations-inventory-current-and-projected-uses
14. Radio Act of 1927, Public Law 632, 69th Congress, §11
15. Nhan, B., et al., “Toward Spectrum Coexistence: First Demonstration of the Effectiveness of Boresight Avoidance between the NRAO Green Bank Telescope and Starlink Satellites,” The Astrophysical Journal Letters 971, 2 (August 2024): https://doi.org/10.3847/2041-8213/ad6b24
16. Green Bank Observatory, Improved Satellite Internet Service for National Radio Quiet Zone (2024): https://greenbankobservatory.org/front-page-news/improved-satellite-internet-service-for-nrqz/