Telescope in flight provides new vistas
By Amanda Jermyn



There are so many ways to observe the universe, from backyard star gazing to space telescopes such as the Hubble. A recent addition is the Stratospheric Observatory for Infrared Astronomy, also known as SOFIA. A joint venture of NASA and the German Space Agency, DLR, (Deutsches Zentrum fur Luft- und Raumfahrt), its telescope does astronomy on the fly from a modified Boeing 747. It is designed for observing celestial objects visible in infrared radiation, part of the non-visible spectrum of light, affording a glimpse of the universe usually denied those with mere mortal vision. Water vapor in the Earthís atmosphere absorbs a large amount of infrared radiation, preventing it from reaching the ground, so infrared telescopes are usually built in dry places at high altitudes, such as on mountain tops, so as to be above most of the water vapor in the atmosphere. Infrared telescopes in space, such as the Spitzer Space Telescope and the Herschel Space Observatory (named for William Herschel who discovered infrared light in 1800) avoid this problem but they are expensive to maintain. So a flying telescope makes a good compromise. Itís cheaper than a space telescope, and with a cruising altitude of about 41,000 feet (7.7 miles above Earth), SOFIA allows infrared light from cosmic objects to be collected above 99% of the obscuring water vapor, and can detect about 80% of the infrared radiation picked up by space telescopes.
The wide- bodied Boeing 747SP chosen for SOFIA was originally acquired by Pan Am World Airways in 1977, sold to United Airlines in 1986, and retired from regular flight service in 1995. It was named Clipper Lindbergh in honor of renowned aviator Charles Lindbergh. Since its purchase by NASA in 1997 it has been specially modified to house a 2.5 meter diameter reflecting telescope (or 8.2 foot, which is bigger than Hubble's 7.9 foot) which looks out of a large door in the side of the fuselage near the aircraftís tail. It is expected to make observing flights three to four nights a week for the next 20 years, and has the advantage of being able to travel to almost any point around the Earth, allowing observation from both the northern and southern hemispheres. On May 26th, 2010 it made its first observations, providing images never seen before of the core of the M82 galaxy, about 12 million light years from Earth, and of heat trapped since the formation of Jupiter escaping through holes in the planetís clouds.
The main goals of the Stratospheric Observatory for Infrared Astronomy include exploring the formation of stars and investigating the physics and chemistry of the interstellar medium, the gas and dust that exists between stars. SOFIA also aims to determine the composition of the atmospheres and surfaces of planets, and to study the evolution, composition and structure of comets. How we perceive our universe depends so much on the lens through which we view it. What worlds yet undreamed of might this new telescope unveil?