In addition to our social media activities on Twitter/X and Facebook, we now launched a page on LinkedIn. We will use this to inform our followers about the progress at the WRC-23 and other interesting developments. In order to keep our readers happy until they wait for the WRC to start, we currently present the European radio astronomy observatories, including some beautiful photos of the telescopes that we all love so much.
By Waleed Madkour and Benjamin Winkel
The World Radiocommunication Conference 2023
The next ITU-R World Radiocommunication Conference (WRC) will take place in Dubai (UAE) from Nov 20 to Dec 15, 2023. Thousands of participants will meet for four weeks to work on possible new allocations to radio services and changes to the Radio Regulations and procedures.
CRAF has worked hard in the past four years to make sure that radio astronomy protection is properly studied and addressed in all preparatory documents, which culminated in the publication of the Report of the Conference Preparatory Meeting (CPM) of the ITU-R. The CPM Report contains various methods and options, which would solve the so-called Agenda Items defined by WRC-19. The Agenda Items represent the tasks to all administrations and stakeholders, to be worked on during a study cycle (3-4 years). They are often about possible new allocations.
CRAF Position Paper
Despite radio astronomy being addressed in the CPM Report, it’s not guaranteed that administrations will actually choose the methods, which include protection of our observations. Therefore, as most other Sector Members of the ITU-R (i.e., non-administrations), CRAF has submitted a paper with our positions to the relevant agenda items:
In the following, we provide a very short version of the text for the most relevant agenda items.
Agenda item 1.2: New spectrum for IMT in 3-10 GHz
An agenda item of major concern for CRAF, in which a frequency identification is proposed for IMT in the frequency range from 6425 to 7125 MHz. A frequency range that is overlapping with a very important spectral line in the band 6650–6675.2 MHz. Although very important for RAS, the band status (protected only by footnote 5.149) is not seen as sufficient by some administrations to provide RAS the required protection at ITU-R level. Any IMT identification in Region 1 in the band 6425–7025 MHz should include appropriate conditions to ensure the continuity of the important RAS operations in the 6650–6675.2 MHz band. Our studies suggest that separation distances of several hundreds of kilometers may be required for this. As proponents of this agenda item have not provided ideas to address this, CRAF strongly supports no change.
Agenda item 1.4: IMT base stations on flying platforms (HIBS)
The proposed allocations for HIBS could have an impact on the RAS band 1610.6–1613.8 MHz from spurious emissions resulting from HIBS operating in the frequency range 694–960 MHz. An impact on the RAS band 2690–2700 MHz from HIBS operating in the adjacent frequency range 2500–2690 MHz is also anticipated by studies. For both cases, appropriate protection provisions will be required in case of any identification made to HIBS in the aforementioned bands.
Agenda item 1.5: Additional IMT spectrum below 1 GHz
Radio astronomy gives considerable importance to the 608–614 MHz band. Without it, there will be a large gap between the 410 MHz and 1 400 MHz RAS allocations, which are vital for studies of continuum radiation. Coexistence between RAS and Mobile services in this band will require stringent protection measures with separation distances of up to 1000 km or more. In case of regulatory changes decided by WRC-23 with mobile service primary allocations, the necessary protection can be achieved by upgrading the RAS secondary allocation to a primary status. This should not change the status of the RAS relative to the broadcasting service as both services are already coordinated in the Geneva Agreement GE-06 provisions.
Agenda item 1.10: Allocation to aeronautical mobile service at 15 and 22 GHz
CRAF supports no change for this agenda item. In case of allocations made to aeronautical mobile services, a primary allocation in the band 15.4–15.7 GHz would be less damaging than a primary allocation in the band 22–22.21 GHz. A protective footnote considering limits for the PFD received in the primary adjacent band at any RAS station together with a guard band of 10 MHz will need to be introduced. It is unclear, how the footnote 5.149 RAS band (22–22.21) could be protected.
Agenda item 1.13: Space research service allocation
No change is supported. Method B is the second supported option because it limits the upgrade to space-to-space links, which will impact RAS at somewhat lower levels. In case methods C, D or E are chosen, new footnotes to protect RAS will be required for both downlink and uplink directions.
Agenda item 9.1 a): Space Weather observations
The choice of priority allocations for receive-only space weather sensors under the MetAids service should take into account the spectrum needs of the RAS related categories; solar flux monitors, solar spectrometers, solar imagers, riometers, and IPS. CRAF supports the continuation of work towards the recognition of receive-only space weather sensors during the next cycle through a WRC-27 agenda item.
Agenda item 10: Proposals for agenda items for future WRCs
CRAF is in full support of a new agenda item for WRC-27, proposed by CEPT. This new AI should seek to study potentially technical and regulatory solutions to address several issues emerging from very large satellite constellations (also known as “mega-constellations”) with respect to radio astronomy.
Currently, RAS is not sufficiently considered when a new satellite filing is processed by the ITU-R. Although our primary bands are often practically affected, the existing protection criteria provided by Recommendation ITU-R RA.769 are not applied, because Articles 9 and 11 of the Radio Regulations do not include appropriate clauses. Likewise, for cases of actual interference from satellite constellations, Resolution 739 does provide only limited solutions from the perspective of a victim service – and it covers only a limited number of the RAS frequency bands that can be affected.
Another open question, which is becoming more and more relevant, is how the total amount of acceptable data loss is handled when more than two active services impact a protected RAS band. Recommendation ITU-R RA.1513 defines a maximum of 5% data loss but no solution how to achieve that. Also, the question of apportionment remains unsolved.
While the above points can potentially be addressed with incremental changes of the Radio Regulations, there are also topics that are completely new. Recently, SKAO and CRAF members detected for the first time unintended electromagnetic radiation (UEMR) leaking from satellite onboard electrics and electronics at low frequencies (UHF band). These are not subject to any regulation, yet they can produce harmful interference, which would violate the RAS thresholds in our primary bands (if the radiation was associated intended radio transmissions, i.e., falling under ITU-R regulation).
Finally, there are satellite operators planning to provide cell-phone connectivity (so-called direct-to-device, D2D) on classical IMT frequency bands under Article 4.4 of the Radio Regulations. Cell-phone frequencies have been allocated for terrestrial use, only. Before base stations in space can be regularly operated, studies would be needed at the ITU-R level (and there are some proposals for such studies, which CRAF supports). As this will take time, some stakeholders want to abuse the Article 4.4 mechanism, which allows countries to bring into use devices, as long as they interfere with no one and do not ask for protection from other services. Satellites, however, do not care for national borders, especially in a region such as Europe, which is not only densely populated but also has many smaller countries.
By Fabio Giovanardi and Michael Lindqvist
Several CRAF members participated in the IAU385 Symposium, October 2023. It took place against the stunning backdrop of La Palma in the Canary Islands. This remarkable event was organised by the International Astronomical Union’s (IAU) new specialised center, the Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS) co-hosted by NSF’s NOIRLab and the SKA Observatory (SKAO). The local organiser was the Instituto de Astrofísica de Canarias. Themed “Astronomy and Satellite Constellations – Pathways Forward,” the meeting brought together astronomers, industry experts, representatives from international policy forums such as the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) and the International Telecommunication Union (ITU), as well as other stakeholders.
Together, we all engaged in illuminating and productive dialogues, focusing on the ongoing initiatives and strategies devised to address the multifaceted impact of satellite constellations on the realms of both optical and radio astronomy. In recent years, the proliferation of satellites in low Earth orbit has been nothing short of dramatic, with projections indicating a potential presence of 100,000 satellites by 2030. This surge in satellite numbers has implications that extend beyond astronomy. It raises concerns about collision risks and the resultant increase in space debris, which, in turn, poses a threat not only to operational satellites but also to the safety and sustainability of outer space.
Recorded presentations and the comprehensive proceedings of this significant symposium will be made available to the public in the upcoming weeks. These invaluable resources promise to provide a wealth of knowledge and insights, serving as a cornerstone for both the scientific community and the general public. It will undoubtedly contribute significantly to the ongoing discourse surrounding the coexistence of astronomy and the growing presence of satellite constellations in our skies.