ITU Spectrum
Coordination
Every satellite that communicates with the ground — including space mirrors — must coordinate its radio frequencies through the International Telecommunication Union. The ITU sits above the FCC in the regulatory hierarchy. Here's how the system works.
The UN Agency That Runs Global Radio
The International Telecommunication Union, headquartered in Geneva, is the United Nations specialised agency responsible for coordinating global use of radio frequencies and satellite orbital positions. Founded in 1865 as the International Telegraph Union — making it the oldest intergovernmental organisation still in operation — the ITU's Radio Regulations are an international treaty binding on all 193 member states. Any satellite using radio spectrum must be coordinated through the ITU's Radiocommunication Sector (ITU-R).
The ITU does not license satellites directly. Instead, each country's national administration — in the US, the FCC — files on behalf of its operators and is responsible for ensuring operators comply with ITU rules. The ITU coordinates filings between administrations, manages interference disputes, and maintains the Master International Frequency Register (MIFR) — the authoritative global database of all coordinated satellite frequency assignments.
For space mirror operators, this means ITU coordination is required for the radio frequencies used in satellite command-and-control — the uplink and downlink used to send pointing instructions and receive telemetry from the mirror. A space mirror does not transmit data in the traditional sense, but it requires radio communications to operate, and those communications require ITU coordination.
How ITU Satellite Filing Works
ADVANCE PUBLICATION
The national administration files an Advance Publication of Information (API) with the ITU between 2 and 7 years before the planned launch date. The API notifies other administrations of the planned satellite network's orbital position, frequency bands, and technical characteristics. The API itself confers no priority rights — it is a notification, not a reservation.
COORDINATION REQUEST
Within the API window, the administration files a Coordination Request (CR/C). This triggers the formal coordination process with other administrations whose satellite networks might be affected by the new filing. All administrations operating satellites on overlapping frequencies in potentially interfering orbital positions must be contacted and must either agree there is no harmful interference or negotiate mitigation measures.
BILATERAL COORDINATION
The filing administration negotiates bilaterally with every affected administration. This can involve dozens of parties for popular frequency bands or orbital positions. Coordination agreements are documented and filed with the ITU. If agreement cannot be reached, the ITU process provides a dispute resolution path — though this is rarely used, as unresolved disputes create legal uncertainty that deters investment.
NOTIFICATION AND RECORDING
Once coordination is complete, the administration files a Notification with the ITU's Radiocommunication Bureau (BR), which records the assignment in the MIFR. An entry in the MIFR gives the frequency assignment a date of "bringing into use" and establishes ITU seniority — later filings in the same frequency/orbit combination must coordinate with the recorded entry, not the other way around.
BRINGING INTO USE
The filing must be "brought into use" within seven years of the API (or a shorter period in some cases) — meaning the satellite must be launched and operated on the coordinated frequencies within that window. Filings not brought into use by the deadline are cancelled. This provision exists to prevent "paper satellite" filings that reserve spectrum without deployment intent.
The Command-and-Control Requirement
Space mirrors do not carry communications payloads — they carry reflective surfaces. But they cannot function without radio communications for attitude control commands and telemetry. The satellite must receive pointing instructions (aim at this ground target, adjust by X milliradians) and return health and status data. These communications use radio frequencies in licensed spectrum bands.
For small satellites like Eärendil-1, the most common bands are the S-band (2–4 GHz) or UHF band for command and telemetry. These bands have ITU allocations for non-geostationary satellite operations, and assignments must be coordinated through the national administration's ITU filing. The FCC's satellite licensing process under Part 25 is directly linked to ITU coordination — the FCC will not grant a full licence without ITU coordination being completed or underway.
The ITU coordination requirement means that any space mirror programme — regardless of its primary mission as a light reflector — is fully embedded in the international radio regulatory framework. It cannot be operated without ITU coordination, and ITU Radio Regulations are binding international treaty law, not voluntary guidelines.
How the ITU Process Has Been Exploited
The ITU's first-come-first-served system for frequency coordination creates a strong incentive to file early and often, even without firm deployment plans. Nations and operators have filed satellite networks years in advance of any realistic deployment timeline to establish ITU seniority — ensuring that later operators must coordinate with their filing rather than the reverse. When enough of these "paper satellites" accumulate in desirable frequency bands and orbital positions, the coordination burden on legitimate new entrants becomes substantial.
The ITU's "bringing into use" milestone requirement — satellites must operate on coordinated frequencies within seven years of filing — was intended to curb paper satellite speculation. But operators have exploited loopholes: launching a single satellite briefly to "bring into use" a filing, then not deploying the full constellation for years. The ITU has tightened these rules at successive World Radiocommunication Conferences (WRCs), but the fundamental incentive to file speculatively remains.
For space mirror operators, the paper satellite landscape means that popular LEO frequency bands — S-band and UHF in particular — may have significant coordination burdens from existing filings. A new entrant must identify all potentially interfering networks in the MIFR and complete bilateral coordination with each filing administration. This is a time-consuming but standard part of the licensing process for any satellite programme.