World’s Largest Airborne Observatory set to Scan Skies

 

The control mechanism is seen from inside the aircraft at the first public viewing of the Stratospheric Observatory for Infrared Astronomy (SOFIA), where a 2.8-meter (98-inch) telescope has been mounted inside specially modified Boeing 747-SP. (AP Photo/Reed Saxon)

A NASA Boeing 747 carrying a huge German-made infrared telescope is on the verge of scanning the skies after years of development. Project officials showed off the world’s largest airborne observatory on April 20, 2010, in a NASA hangar in Southern California’s high desert, where it has been undergoing flight testing. The 40,000-pound telescope assembly is mounted in the rear of the former Pan Am jetliner. In flight, a huge hatch opens to allow the 98-inch-diameter telescope to see its celestial targets.

The Stratospheric Observatory for Infrared Astronomy — SOFIA for short — is expected to capture its first infrared images in flight in six to eight weeks. Initial targets will be planets, for calibration purposes. Project officials describe it as a “near-Hubble-class” observatory, referring to the orbiting Hubble Space Telescope, which has returned astonishing images of the universe since its launch 20 years ago.

SOFIA also is expected to last for at least 20 years, drawing scientists to Palmdale for long-duration, high-altitude flights.

“They’ll be working on unlocking the secrets about the universe and our own solar system,” said Bob Meyer, SOFIA program director for NASA’s Dryden Aircraft Operations Facility and Ames Research Center at Moffett Field, CA.

NASA’s partner is the German Aerospace Center, known by the initials DLR, which will receive about 20 percent of observing time.

SOFIA is a leap in scale for airborne astronomy. In the 1960s, planetary scientist Gerard Kuiper initiated the concept by pointing a 12-inch telescope out a window of an airliner, and others followed. From the 1970s to mid-1990s, NASA flew a 36-inch telescope in a former military cargo plane.

The Stratospheric Observatory for Infrared Astronomy (SOFIA), a cooperative venture between NASA and the German Aerospace Center, known by the initials DLR, at a NASA Dryden Flight Research Center test facility in Palmdale, CA, April 20, 2010. (AP Photo/Reed Saxon)

SOFIA will look for objects that emit radiation in infrared wavelengths, which are not visible to the human eye. Infrared telescopes also can see through the huge clouds of dust in the universe that block visible light.

Airborne telescopes have an advantage over ground-based observatories because they don’t have to peer through a moisture-laden atmosphere, and unlike satellite telescopes, they can be constantly updated and repaired and are not bound by the limits of a fixed orbit, officials said.

Project officials said SOFIA will fly at altitudes above 99 percent of the water vapor in the atmosphere. The goal is flights at 45,000 feet with about eight hours of observation time.

The telescope will be cryogenically chilled before takeoff so that the mirror doesn’t sustain a thermal shock when the cavity door is opened at high altitude.

The Boeing 747SP was delivered to Pan Am in 1977 and was christened the Clipper Lindbergh by Charles Lindbergh’s widow on the 50th anniversary of his historic flight across the Atlantic. It was later sold to United Air Lines before NASA acquired it in 1997. Lindbergh’s grandson Erik rechristened it in 2007.