Radio pollution: the invisible threat to radio astronomy

The radio spectrum offers a magnificent window on the universe, unobscured by the clouds of gas and dust which hinder observations at most other wavelengths. However, our view through the radio window is now being obscured by growing levels of man-made radio interference. Transmitters on satellites have become a particularly series threat to the future development of radio astronomy as they are able to affect radio telescopes anywhere on the surface of the Earth. Interference is not confined to the main transmission frequency bands, but may spread over much wider tracts of the radio spectrum through careless engineering. Coordinated action will be needed to keep the radio window clean for future generations to enjoy.