The Stratospheric Observatory for Infrared Astronomy (SOFIA), developed jointly by NASA and the German Aerospace Center, is a Boeing 747 jet with a twist: Instead of passenger seats, the plane’s cabin houses a powerful, 17-ton telescope capable of imaging submillimeter, infrared, and visible light wavelengths.
With four engines each generating 50,000 pounds of thrust, SOFIA can cruise at 520 miles per hour and reach an altitude of about 40,000 feet. The 98-inch telescope—the largest ever borne aloft in a flying observatory—accesses the sky through a 14-by-20-foot opening in the fuselage. During SOFIA’s first test run with the doors open this past December, pilots reported that the craft handled well despite the gaping hole in its side.
Specialized modifications to the plane allow the smooth ride needed for precise observations. A gyroscope system keeps the craft steady, while the Fast Diagnostic Camera monitors image quality and the Focal Plane Imager locks the telescope onto its celestial targets. SOFIA’s Faint Object Infrared Camera will examine the Milky Way’s tumultuous center, star-forming regions, dust clouds, and nearby galaxies. Other instruments aboard include the High-Speed Imaging Photometer for Occultation, which will observe objects such as planets, satellites, and asteroids as they pass in front of stars, and the German Receiver for Astronomy at Terahertz Frequencies, which will determine the chemical composition of interstellar gas clouds.