An automated telescope that orbits Earth at an altitude of 600 km (375 miles). The National Aeronautics and Space Administration and the European Space Agency built the telescope. Its primary mirror is 2.4 meters (94.5 inches) in diameter. The telescope contains an array of instruments capable of carrying out a variety of high-quality astronomical observations at ultraviolet, optical, and infrared wavelengths. Because the telescope is above Earth’s atmosphere, it can obtain extremely clear images.