CRAF concerned over electromagnetic leakage from satellite constellations that could impact astronomical observations.


As detailed in a new article published in Astronomy & Astrophysics, for the first time, leakage radiation from onboard spacecraft electronics was systematically studied by astronomers with the LOFAR telescope. In the hour-long observation, 68 satellites of a large satellite constellation crossed the telescope’s field of view. Most of them revealed radiation at frequencies far below the normal communication signals’ frequencies. Astronomers are now concerned that this adds yet another channel of interference to universe observation.

Radio telescopes must be [CS2] extremely sensitive to pick up the faintest signals from the Universe, which have traveled enormous distances before reaching Earth. A cell phone on the Moon would be among the brightest sources in the sky, for a radio astronomer. Therefore, great effort is necessary to keep the immediate surroundings of an observatory clean from anthropogenic signals. But humankind has developed a huge number of applications, from radio and TV, over car radars, to high-bandwidth communication to provide Internet connectivity. All these are orders of magnitudes brighter than the signals from space. Protection of radio observatories is thus crucial. This can be achieved by coordinating the use of certain frequencies, ensuring geographical separation or limiting transmitter powers. 

A Need for Regulation

The new findings on electromagnetic leakage from satellite constellations are related to a type of radiation that is not subject to the regulatory processes of the International Telecommunication Union (ITU) or the European Conference of Postal and Telecommunication Administrations (CEPT). CRAF is concerned that the increase in low-earth orbit satellites – over 5000 new satellites in recent years – may negatively impact observations with radio telescopes which operate at low frequencies, below about 1 GHz. CRAF invites regulation authorities and administrations to consider this aspect and improve the regulation and best practices for this. This topic should be addressed before satellite launches.

The Committee on Radio Astronomy Frequencies

The Committee on Radio Astronomy Frequencies (CRAF) is a collaboration of scientists from European research institutes and organisations who work towards the reduction of interference into radio astronomical observations. CRAF is operated under the umbrella of the European Science Foundation (ESF), as one of their “Expert Committees”. Several CRAF members were involved in the newly released study.

CRAF is heavily involved in the regulatory processes at national and international level, working together with the International Telecommunication Union (ITU), the European Conference of Postal and Telecommunication Administrations (CEPT), but also national network agencies.

Cooperation with satellite industry

Last year, the International Astronomical Union formed theCentre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS) as a place for collaboration of all stakeholders, i.e., regulators, satellite industry, professional and amateur astronomers, and humans who simply enjoy the night sky or have a cultural relationship with it. CRAF is a strong supporter of the CPS. Cooperation with industry is ongoing and CRAF is confident that good solutions to this new challenge can and will be found.


The official press release by the CPS can be found here: 

Press contact:

CRAF: contact[at]