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Dec. 11, 2001

Michael Mewhinney

NASA Ames Research Center, Moffett Field, Calif.

Phone: 650/604-3937 or 650/604-9000

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NOTE TO EDITORS AND NEWS DIRECTORS: News media are invited to see and photograph the new Stratospheric Observatory for Infrared Astronomy (SOFIA) exhibit at NASA Ames Research Center, Moffett Field, Calif. The exhibit is located in the NASA Ames Visitor Center and can be viewed Monday through Friday from 8:00 a.m. to 4:30 p.m. PST. To arrange an interview about the exhibit, please contact Mike Bennett, SOFIA education and public outreach, at 650/604-2128.


A new exhibit featuring an actual wind tunnel model of the Stratospheric Observatory for Infrared Astronomy (SOFIA) opens today in the Visitor Center at NASA Ames Research Center, Moffett Field, Calif. The free exhibit is open to the public Monday through Friday from 8 a.m. to 4:30 p.m. PST.

SOFIA is an astronomical observatory that will conduct observations beginning in 2004 at an altitude of about 41,000 feet aboard a modified Boeing 747SP aircraft operated and maintained by United Airlines. While using airborne telescopes is not new, SOFIA will be the world’s largest and most powerful, considerably larger and more sophisticated than its predecessor, the Kuiper Airborne Observatory that was based at Ames from 1971 to 1995. SOFIA will feature a 98.4-inch (2.5 meter) telescope located behind a door that will open to the atmosphere, permitting observation of planets, stars and other phenomena.

"This very accurate model of a 747 spent hundreds of hours inside a wind tunnel at Ames, helping NASA engineers understand how an open cavity in the side of the airplane would affect its flight characteristics," explained Mike Bennett, SOFIA education and public outreach. "Now, in a wonderful example of creative recycling, the model is embarking on a second career in education. In the future, it will help thousands of students and other visitors understand more about the many different kinds of technologies that modern scientists use to study the universe."

To determine how SOFIA will fly, Ames aerospace engineers tested the one-fourteenth scale model featured in the exhibit for more than 100 hours in Ames’14-foot wind tunnel. Their purpose was to study the airflow over the telescope’s open door in the aircraft’s fuselage. Engineers studied the amount of airflow over and into the cavity when the observatory’s telescope door is open; the effects of varying wind pressure on various parts of the telescope when the door is open; and the effects of the disturbed air flow on the aircraft’s tail surfaces.

As a result of the wind tunnel tests, engineers developed a unique design for the telescope’s aperture (the opening through which the telescope looks). On most observatories, the aperture is simply a round hole about the same size as the front of the telescope. However, on SOFIA, the aperture is modified by the addition of an "aft ramp," a sort of wind scoop located on the end of the aperture’s assembly.

Normally, as air flows over the open cavity, it tends to drop down into the hole, creating turbulence and varying pressures inside the telescope cavity. However, with the addition of the specially designed aft ramp, just the right amount of the airflow was lifted back out, creating smoother airflow across the face of the opening and less turbulence inside the cavity. Air turbulence inside the cavity creates small vibrations and distortions in the telescope, which reduces its image quality. Exhibit visitors will be able to see the movement of the telescope’s aperture and the opening and closing of the telescope’s door by pushing a button.

NASA awarded a $484.2 million contract to Universities Space Research Association, Columbia, Md., in December 1996, to acquire, develop and operate SOFIA. Other team members include Raytheon Aircraft Integration Systems, Waco, Texas; United Airlines, San Francisco; the University of California, Los Angeles, Berkeley and Santa Cruz, Calif.; the Astronomical Society of the Pacific, San Francisco; the SETI Institute, Mountain View, Calif. SOFIA’s complex telescope is being developed by DLR, the German Aerospace Center, located in Bonn.

Annual operating costs of SOFIA are anticipated to be about $40 million. SOFIA’s first test flight is currently scheduled in October 2003 at Raytheon’s Waco, TX, flight facility. SOFIA is scheduled to arrive at Ames in May 2004 for final testing preparatory to full-scale operations starting in late 2004. Further information about SOFIA is available on the SOFIA web site, located at:



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