The field of radio astronomy, which has been instrumental in uncovering the universe's secrets since Karl Jansky's initial discovery in the 1930s, is now confronting a significant challenge from the rapid expansion of satellite constellations. These networks, primarily designed for global internet connectivity, are inadvertently creating a new source of cosmic noise that hinders astronomical observations.
Radio astronomy's origins trace back to Jansky's detection of radio waves from the Milky Way, opening a new avenue for observing celestial phenomena beyond the reach of optical telescopes. Advancements post-World War II led to sophisticated instruments like China's FAST and the Square Kilometre Array (SKA). As of September 2025, SpaceX's Starlink constellation alone comprises over 8,475 satellites, with plans for tens of thousands more, significantly amplifying the potential for radio interference. Observations have detected unintended electromagnetic radiation (UEMR) from these satellites, creating a pervasive radio hum that can obscure faint signals from distant cosmic sources.
In response to this growing concern, a collaborative effort is underway between astronomers and satellite operators to develop mitigation strategies. SpaceX is working with the International Astronomical Union's Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS) to explore technical adjustments that can reduce UEMR. The United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) has also initiated discussions to establish international guidelines for preserving radio quiet zones, which are crucial for sensitive astronomical research.
Furthering these efforts, the Committee on Radio Astronomy Frequencies (CRAF) has become an I-member of the International Special Committee on Radio Interference (CISPR). This move, as of September 2025, signifies a proactive approach to integrate radio astronomy's needs into global electromagnetic compatibility standards, aiming to ensure that both satellite services and vital scientific research can coexist harmoniously.