The Stratospheric Observatory for Infrared Astronomy, SOFIA, is an extensively modified Boeing 747SP aircraft carrying a reflecting telescope with an effective diameter of 2.5 meters (100 inches). SOFIA studies many different kinds of astronomical objects and phenomena, including the lifecycle of stars, the formation of new solar systems, black holes at the center of galaxies, and complex molecules in space. The observatory's instruments — cameras, spectrometers, and photometers — operate in the near-, mid- and far-infrared wavelengths, enabling scientists onboard to study the solar system and beyond while flying at 38,000- 45,000 feet.
SOFIA underwent numerous flight testing after modifications turned what had once been a passenger aircraft into NASA's flying observatory. Testing the telescope cavity door and the airflow over the cavity were integral.