In the world · Science · 15 December 2023
ITU and satellites: protecting radio astronomy by 2027
At WRC-23, the ITU's 193 countries put protecting radio telescopes from satellites on the 2027 agenda. The hydrogen band is at the center.
bairogonzalez.com team, drawing on Bairo's story · Published
At the 2023 World Radiocommunication Conference, WRC-23, held in Dubai and closed in December, the 193 member countries of the International Telecommunication Union unanimously approved a new item for the next conference: studying how to protect radio astronomy from interference by large satellite constellations. The item became number 1.16 on the agenda of WRC-27, scheduled for October and November 2027 in Shanghai. According to the SKA Observatory itself, it was the first item dedicated to radio astronomy in more than a decade. At the center of the discussion is the 1,400 to 1,427 MHz band, home to the hydrogen line.
What happened
World radiocommunication conferences take place every three or four years and revise the Radio Regulations, the treaty that divides the spectrum among services. That is where footnote 5.340 sits, prohibiting all emissions in certain bands, among them 1,400 to 1,427 MHz.
In Dubai, the proposal for new studies was backed by countries such as Australia, Canada, Chile, China, Germany, France, Japan, South Africa, Tonga and the United States, with the participation of the SKA and the European committee on radio astronomy frequencies. The approved text became Resolution 681 (WRC-23). Federico Di Vruno, spectrum manager at the SKA, called the decision a significant step in protecting radio astronomy.
In September 2026, the ITU itself published an analysis of what is at stake, written by Balthasar Indermuehle, of the Australian science agency CSIRO, who chairs the ITU group dedicated to radio astronomy. The text describes three lines of study: interference from a single satellite system in seven radio astronomy bands; the combined interference of several systems, the hardest problem; and the protection of two specific radio-quiet zones. The article calls the 1,400 to 1,427 MHz band the most important radio astronomy band there is, because it protects the 21 cm line of neutral hydrogen.
Why it matters
The protection of 1,400 to 1,427 MHz was conceived in an era of ground-based transmitters. It prohibits emitting inside the band, but what worries astronomers today is what happens beside and above it: thousands of satellites operating in neighboring bands, whose unwanted emissions, added together, can leak into the silence. The same ITU analysis notes that direct-to-cell satellite services in nearby bands also need careful study.
The road to 2027 is short. Regional groups finalize their positions between late 2026 and 2027. What is decided in Shanghai will determine how long humanity will keep hearing the hydrogen of the universe as cleanly as it does today.
In Bairo's view
For Bairo, few human agreements are as beautiful as the one that left the hydrogen band in silence. Countries that disagree on almost everything agreed not to speak on one piece of the spectrum, just to keep listening to the sky. WRC-23 showed that this agreement still has defenders, unanimously.
That is where the meaning he gives to the number 1420 comes from: a symbol of silence and listening, measured by the 21 cm yardstick. No one transmits on 1420 MHz, and the project he founded only pays tribute to the band, with digital records.
In his reading, rules that protect what is fragile need to be revisited when technology changes. That holds for the spectrum and it holds for information. The algorithms that protect data today will also have to change when quantum computers mature. That is the benefit he proposes with qrqbits: post-quantum protection, designed before the problem arrives.
Where this meets the ecosystem
1420mhz, created by CLAIN, carries the name of the band under discussion. For the project, following WRC-27 is a matter of coherence: whoever pays tribute to silence has to know how it is protected. Bairo's fronts do not take part in the ITU negotiations.
Sources
- SKAO, UN agency to study new protections for radio astronomy, 12/20/2023.
- ITU, "Radio astronomy at the regulatory crossroads: WRC-27 and beyond", 09/08/2026.
- ITU, Radio Regulations, radio astronomy allocations and footnote 5.340.
- SpaceNews, what was at stake for space at WRC-23, 2023.
Read also
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- FAST turns ten: China's great ear and the signals
- SKA: the giant observatory begins to hear hydrogen
- Breakthrough Listen: ten years listening to the universe
- Starlink and radio astronomy: the noise from the sky
- Post-quantum migration: the 2030 and 2035 deadlines