NASA's Stratospheric Observatory for Infrared Astronomy, or SOFIA, has passed a significant mission milestone. It has completed the first phase of experimental flight tests, which confirmed the structural integrity and performance of the modified 747SP SOFIA aircraft that carries a huge infrared telescope.

The telescope measures nearly 10 feet in width and weighs almost 19 tons. It peers through a 16-foot-high door cut into SOFIA's 747 fuselage. During this test series, the aircraft flew five times with this external door closed. These flights tested the limits of the aircraft's capabilities in many areas, including aerodynamics, structural integrity, stability and control, and handling qualities.

"SOFIA is already a technological marvel, and will soon be a powerful tool for studying the birth and evolution of planets, stars, and galaxies," said Alan Stern, associate administrator of NASA's Science Mission Directorate, NASA Headquarters, Washington. "The completion of its closed door testing phase is a major milestone on the way to SOFIA's inaugural science flights next year."

The SOFIA program also checked the functionality of the aircraft's cutting edge, German-built telescope. Engineers tested the ability of the instrument's control system to maintain its precise position when tracking a celestial object, even while the aircraft moves and maneuvers through the sky.

"The project finished a very important milestone on the path to the first astronomy work with the telescope, which is expected in early 2009," said Robert Meyer Jr., SOFIA program manager at NASA's Dryden Flight Research Center, Edwards Air Force Base, Calif.

The aircraft now will undergo installation and integration of the remaining elements of the observatory before open-door test flights scheduled to begin in late 2008. After completing the initial open-door test flight, limited science observation flights will begin in 2009. The science community will survey the universe with five specialized instruments on SOFIA as the observatory begins normal science observation flights in 2011. The observatory reaches full operational capabilities in 2014.

The SOFIA aircraft is based at Dryden's newly established Aircraft Operations Facility in Palmdale, Calif., where it will remain for additional development, flight testing and science flight operations. The program is a partnership of NASA and the German Aerospace Center. Dryden manages the SOFIA program. NASA's Ames Research Center, Moffett Field, Calif., manages the science project.

FMI: www.nasa.gov/mission_pages/SOFIA/index.html, www.nasa.gov/centers/dryden/home/index.html