Britannica Sources used in this answer

Why are some radio telescopes placed in space?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Radio telescope Lovell Telescope, a fully steerable radio telescope at Jodrell Bank, Macclesfield, Cheshire, England.

While most radio waves pass through Earth’s atmosphere without significant distortion, some radio telescopes are placed in space to overcome specific limitations encountered on the ground:

Atmospheric Interference: Observations at very long wavelengths can be distorted by the ionosphere, while observations at very short (submillimetre) wavelengths are affected by water vapour and oxygen in the atmosphere.1
Thermal Noise: Space-based placement allows for precision observations at all wavelengths by avoiding thermal radiation emitted from the ground.1
Enhanced Resolution: Space-based instruments can be used in conjunction with ground-based telescopes to create massive radio interferometers with baselines spanning tens of thousands of kilometres, significantly improving angular resolution.2

These space-based missions have been instrumental in detecting fluctuations in the cosmic microwave background and determining the age and composition of the universe.1