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Cislunar Communications: the way ahead

As soon as one World Radiocommunication Conference (WRC) ends, preparatory work begins for the next one as, inevitably, issues requiring further study have been identified and so are assigned to the various ITU-Radiocommunication (ITU-R) Study Groups.


In this, the first of a series of blogs considering the outcomes of WRC-23, we are looking at Resolution 680 (WRC-23) covering cislunar communications. As discussed in the third pre-WRC blog, advances in technology, coupled with an increased interest in both deep space astronomy and commercial operations on the lunar surface, have raised the visibility and importance of this topic.


Resolution 680 (WRC-23) mandates ITU-R Study Groups to undertake “studies on frequency-related matters, including possible new or modified space research service (SRS) (space-to-space) allocations, for future development of communications on the lunar service and between lunar orbit and the lunar surface.”


Under this Resolution, the ITU-R is invited to study, prior to WRC-27, (the next conference), “the spectrum needs of systems in the SRS which may operate on the lunar surface, or systems in lunar orbit communicating with systems on the lunar surface.” 11 specific frequency ranges in UHF, S, C, X, and Ka band have been identified for study. The three lowest frequency ranges in UHF are limited to use outside of the Shielded Zone of the Moon (SZM). This is an area of the Moon and associated airspace protected for astronomy and other passive services. The SZM is shielded from any emissions originating from within 100,000 kilometres of the centre of the Earth.


In the studies, the specific technical and operational characteristics, as well as the protection criteria, for systems that would operate in the SRS in the specified frequency bands are to be taken into consideration. The ITU considers SRS to be for scientific or technological research purposes only, and so these studies will be led by ITU-R Study Group 7 (Science Services).


Due to the absence of appreciable water vapour and oxygen in the lunar atmosphere, radioastronomical observations that would be impossible from Earth can be made from the Moon. In consideration of this fact, the studies are also to include “protection criteria to be applied for the protection of the radio astronomy service (RAS) and SRS active and passive sensors on the lunar surface and lunar orbit.”


Looking even beyond WRC-27, the Resolution notes that “lunar scientific and exploration activities can advance the development of potential future space activities beyond space research, which may in the future include other relevant radiocommunication services for lunar communications.” In light of this, the ITU-R is invited to begin studying future spectrum needs for lunar communications and systems beyond those identified to be studied in time for inclusion in WRC-27. This may well result in an agenda item at WRC-31 pertaining to frequency bands for commercial applications.


Article 22 solidified


In our previous blog on this subject, we looked at several issues pertaining to cislunar communications. One was the fact that although there are two mechanisms in the ITU Radio Regulations (Edition of 2020) in place to protect and manage cislunar communications, neither of those mechanisms have “teeth.” In other words, it was not a requirement for administrations to describe or commit as to how they would protect the SZM. The regulations will now change. Appendix 4 of the Radio Regulations will be updated to include two new requirements for the notification of a lunar satellite network: firstly, a commitment by the notifying administration of compliance to protect the SZM in accordance with the provisions of Article 22; and secondly, a technical or operational description of how the administration intends to ensure this compliance.


There is obviously still a great deal of work to be done before there will be a clear framework in place for allocating and protecting frequencies for lunar ventures, whether scientific or commercial. This is where our expertise and experience in navigating the regulation minefield comes into play. We can guide you to the best course for your particular application.



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