ESA astronaut Marco Sieber journeyed deep underground in Italy's Apennines for CAVES training
Radio astronomy opens a window onto the invisible universe. While our eyes can detect visible light, countless objects in space emit radiation at much longer wavelengths, in the radio portion of the electromagnetic spectrum. Where visible light gets blocked by interstellar dust, radio waves pass through unrestricted revealing objects that remain completely invisible to traditional telescopes. Radio telescopes detect these waves, revealing phenomena that optical telescopes simply cannot see. Radio waves also penetrate Earth's atmosphere far more easily than many other wavelengths, making ground-based radio observatories incredibly effective tools for exploring the universe.

