Watching the stars with increasingly better techniques: Astronomers are eagerly waiting to begin use of a new instrument to study celestial objects: a high-resolution, mid-infrared spectrograph mounted on NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA), the world's largest flying telescope.


The so-called Echelon-Cross-Echelle Spectrograph (EXES), can separate wavelengths of light to a precision of one part in 100,000. At the core of EXES is an approximately 3-foot (1 meter) bar of aluminum called an echelon grating, carefully machined to act as 130 separate mirrors that split light from the telescope into an infrared "rainbow."


The airplane called SOFIA is a heavily modified Boeing 747 Special Performance jetliner that carries a telescope with an effective diameter of about 8-feet (2.5-meters) at altitudes of 39,000 to 45,000 feet (12 to 14 km), above more than 99 percent of Earth's atmospheric water vapor. Lower in the atmosphere, at altitudes associated with most ground-based observatories, water vapor obscures much of what can be learned when viewed in the infrared spectrum.


"The combination of EXES's high spectral resolution and SOFIA's access to infrared radiation from space provides an unprecedented ability to study celestial objects at wavelengths unavailable from ground-based telescopes," said Pamela Marcum, a program scientist at the SOFIA Science Center and Program Office in Moffett Field, California. "EXES on SOFIA will provide data that cannot be obtained by any other astronomical facility on the ground or in space, including all past, present or those observatories now under development."




SOFIA SkyLab



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