The Stratospheric Observatory for Infrared Astronomy (SOFIA), which is a joint project of NASA and the German Aerospace Center (DLR), nears operational phase and NASA has allowed limited visiting while the device was at the space agency's Ames Research Center in Mountain View.

SOFIA is actually a modified Boeing 747SP airliner which carries a 2.5-meter reflector telescope. It is designed to fly at more than 45,000 feet, above most of water vapor in the Earth's atmosphere. The three-mirror telescope looks out of a large opening in the side of the fuselage close to the airplane's tail. The SOFIA will initially carry nine instruments for infrared astronomy and high-speed optical astronomy.

"It's a new way to conduct important research about the universe," said John Logsdon, director of the Space Policy Institute at George Washington University, as quoted by the SJ Mercury News. "We've operated telescopes on Earth, we've operated telescopes in space, but never one onboard an operating aircraft."

The Boeing 747SP has a shorter fuselage than the "normal" 747 and NASA purchased it from United Airlines in 1997 for use by the SOFIA project. The maiden flight of the SOFIA observatory took place on 26 April, 2007, with tests still underway before the plane is given the OK to enter service, sometime early in 2009. SOFIA is expected to fly around 20 years.

The main advantage of SOFIA over Hubble and the next space telescopes is that it's much easier to repair and modify. It will cost around $75 million a year to operate. Furthermore, it can travel to any part of the world for observations. The entire project cost around $600 million, much more than the initially estimated $185 million.

The plane was christened Clipper Lindbergh by Lindbergh's widow, Anne Morrow Lindbergh, on the occasion of the 50th anniversary of her husband's historic flight from New York to Paris in 1927.