For the first time, scientists have peered at the stars using the
newly installed telescope aboard NASA’s Stratospheric Observatory for
Infrared Astronomy (SOFIA), the largest airborne observatory in the
world.

During the night of Aug. 18-19 in its first ‘on-sky test,’ the
telescope was pointed at the star Polaris. A crisp white dot appeared
on astronomers’ computer screens inside the aircraft, demonstrating
that the telescope’s basic optical, mechanical and software systems
all are functioning properly.

“This is an important milestone from an engineering perspective,
because all the telescope subsystems have been integrated on the
aircraft for the first time, and it substantiates all the engineering
design and interface work performed on both sides of the Atlantic,”
said Kaiser Adeni of NASA Ames Research Center and NASA’s deputy
chief engineer for the SOFIA Project.

“Our first look at a star shows that the most basic requirements for
observing with SOFIA have been met,” said Dr. Ted Dunham, an
instrument scientist at the Lowell Observatory, Flagstaff, Ariz., and
principal investigator for SOFIA’s High-speed Imaging Photometer for
Occultations (HIPO) team.

While it was not designed to conduct any airborne science
observations, the test did provide a team of SOFIA scientists and
engineers on the ground with an opportunity to calibrate the
telescope and the newly installed HIPO, the first scientific
instrument aboard SOFIA. Scientists plan to conduct ground-based
observations of the sky aboard SOFIA for the next three weeks.

“This is more than a fantastic milestone for the observatory,” said
Dr. Eric Becklin, chief scientist for SOFIA’s prime contractor,
Universities Space Research Association (USRA), Columbia, Md. “It
also demonstrates the ability and teamwork of all the major
participants in the project.”

Flying at altitudes above 40,000 feet, SOFIA will help astronomers
learn more about the birth of stars, the formation of solar systems,
the origin of complex molecules in space, the nature and evolution of
comets, how galaxies change with time and even the nature of the
mysterious black holes lying at the centers of some galaxies,
including our own.

Prior to the ‘first look,’ a team composed of scientists and
engineers from NASA Ames, USRA; L-3 Communications Integrated
Systems, Waco, Texas; and Lowell Observatory completed installation
of HIPO on SOFIA’s complex telescope assembly.

Scientists use HIPO to provide high-speed, time-resolved imaging
photometry at two optical wavelengths. HIPO has a flexible optical
system and numerous readout modes, which allow many specialized
observations to be made. The primary function of HIPO is to observe
stellar occultations. During a stellar occultation, a star serves as
a small probe of the atmospheric structure of a solar system object,
or the surface density structure of a planetary ring or comet.

During observations over the next few weeks, the integration team
hopes to calibrate SOFIA’s telescope subsystems using HIPO and see if
there are any distortions in the airborne observatory’s telescope.

“Installation of HIPO is the final building block in the functional
integration process that has taken approximately five months,” Adeni
said. “Now, over the next few weeks, we need to characterize the
behavior and performance of the telescope and make sure everything is
working the way it is supposed to.”

NASA awarded a $484.2 million contract to USRA in December 1996 to
acquire, develop and operate SOFIA. Other team members include L-3
Communications Integrated Systems; Evergreen Airlines; the University
of California, Los Angeles, Berkeley and Santa Cruz, Calif.; the
Astronomical Society of the Pacific, San Francisco; and the SETI
Institute, Mountain View, Calif.

SOFIA’s telescope assembly, a 98.4-inch (2.5 meter) aperture-diameter
telescope, was developed by DLR, the German Aerospace Center, located
in Bonn. MAN Technologies AG, Mainz and Augsburg, Germany, built the
telescope. Its optics and tracking system were supplied by
Kayser-Threde Corp., Munich, Germany. Several other sub-contractors
located in Europe also helped fabricate the complex telescope. The
telescope assembly was delivered to L-3 Communications in September
2002.

SOFIA will be based at NASA Ames Research Center in California’s
Silicon Valley. Scientific management of the observatory operations
will be conducted for NASA by USRA. Evergreen Airlines will be
responsible for maintenance and flight operations.

For more information about SOFIA, please visit: http://sofia.nasa.gov