NASA's Airborne Infrared Observatory Sees first light

Palmdale, CA--The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint program by NASA and the German Aerospace Center, achieved a major milestone on May 26 with its first in-flight night observations.

The highly modified SOFIA Boeing 747SP jetliner fitted with a 2.7-m-diameter reflecting telescope took off from its home base at the Aircraft Operations Facility in NASA's Dryden Flight Research Center. The in-flight personnel consisted of an international crew from NASA, the Universities Space Research Association (Columbia, MD), Cornell University (Ithaca, NY), and the German SOFIA Institute (DSI; Stuttgart, Germany). During the nearly eight-hour flight, at altitudes up to 35,000 feet, the crew of 10 scientists, astronomers, engineers, and technicians gathered telescope performance data at consoles in the aircraft's main cabin.

The SOFIA telescope contains a paraboloidal 2.7 m primary mirror and a hyperbolic secondary mirror. A flat tertiary mirror reflects the IR beam to the focus; the tertiary can be replaced with a dichroic mirror that separates visible from IR. The instrument has three cameras: the Focal Plane Image (a guiding camera), the Wide Field Imager, and the Fine Field Imager.

Two decades of operation planned
"With this flight, SOFIA begins a 20 year journey that will enable a wide variety of astronomical science observations not possible from other Earth and space-borne observatories," said Jon Morse, Astrophysics Division director in the Science Mission Directorate at NASA Headquarters in Washington.

According to Bob Meyer, NASA's SOFIA program manager, the team has retired many of the risks and threats associated with this first-light flight. "This was a major accomplishment in terms of understanding the quality of our observations, for example how much image instability we encounter with airflow over the telescope. While improvements can be made, we clearly exceeded expectations."

The stability and precise pointing of the German-built telescope met or exceeded the expectations of the engineers and astronomers who put it through its paces during the flight.

The scientists recorded images of the Messier 82 (M82) galaxy and of Jupiter at wavelengths unobservable by ground- or space-based telescopes. The composite image of Jupiter shows heat pouring out of the planet's interior through holes in its clouds. In the infrared image of M82, it is possible to look through the galaxy's interstellar dust clouds to show several "starburst" knots in which stars are forming by the tens of thousands.

"At its maximum observation ceiling, SOFIA is above more than 99% of the water vapor in Earth's atmosphere, and so can receive a large part of cosmic infrared radiation which is otherwise absorbed by Earth's atmosphere," said Paul Hertz, chief scientist or NASA's Science Mission Directorate.

Astronomers have their chance
"A preliminary examination of the first light data shows that the images are in fact sharp enough to enable cutting-edge astronomy," said Alfred Krabbe, director and scientific head of DSI. "Now, at last, the fun begins."

SOFIA is a joint program between NASA and the German Aerospace Center, Deutsches Zentrum für Luft- und Raumfahrt (DLR; Bonn, Germany).