NASA begins testing of new spectrograph on SOFIA observatory

Jun 03, 2014
EXES, the Echelon-Cross-Echelle Spectrograph, made its first light flight on April 7, 2014. The instrument is a mid-infrared spectrograph and is shown mounted to SOFIA's telescope. Credit: NASA/SOFIA/EXES/Mathew Richter

(Phys.org) —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.

This new instrument, the 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."

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 . 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 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."

EXES successfully carried out its first two flights on SOFIA on the nights of April 7 and 9, according to Matthew Richter, leader of the team that is developing the instrument at the University of California, Davis, Physics Department. EXES is a collaboration between U.C. Davis and NASA's Ames Research Center in Moffett Field.

"During the two flights, EXES made observations to investigate and characterize the instrument's performance. All the main goals of these observations were successful, although further commissioning flights are required to test EXES in all of its modes," said Richter.

On the first commissioning flight, EXES observed emissions from Jupiter's atmosphere in two molecular hydrogen lines. These observations will be used to understand how gas rises from deep in Jupiter's interior and mixes into the planet's upper atmosphere.

During the second commissioning flight, EXES observed a young, massive star in the constellation Cygnus that is still embedded in its natal cocoon. The star, known as AFGL 2591, warms up the surrounding interstellar dust and causes ice coatings on the dust to evaporate. The warmed dust provides an excellent background infrared "lamp" to probe the chemical make-up of the intervening gas.

New stars and planets are forming from that material through processes similar to the ones that made the sun and Earth. These observations are designed to study water vapor around the protostar, and demonstrate that EXES can detect absorption from the lowest energy level of water molecules despite interference from from Earth's atmosphere.

"Of the observations obtained during the instrument's first flights, only one can be done from the ground, albeit with some difficulty, and the others are impossible from even the best ground-based telescope sites because the water in Earth's atmosphere is opaque at these wavelengths," Richter said. "While space observatories are above Earth's atmosphere, the massive optical equipment required to separate the light as finely as EXES does – EXES weighs almost 1,000 pounds – would be a challenge to launch into space. In these observations, the spectral features we are studying are narrow, and finely dividing the to detect them is exactly what EXES was designed to do."

Explore further: Astronomers see pebbles poised to make planets

Related Stories

SOFIA set to begin cycle two astronomy observations

Nov 06, 2013

NASA, the German Aerospace Center (DLR), the SOFIA Science Center, and the German SOFIA Institute (DSI) have announced the selection of 51 investigations to study the universe using the Stratospheric Observatory ...

SOFIA peers in to the heart of the Orion nebula

Dec 20, 2011

(PhysOrg.com) -- A new image from NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) shows a complex distribution of interstellar dust and stars in the Orion nebula. Interstellar dust, composed ...

GREAT spectrometer readied for flight on SOFIA

Mar 31, 2011

(PhysOrg.com) -- Scientists recently completed a series of nighttime, ground-based testing of the German Receiver for Astronomy at Terahertz Frequencies, or GREAT, spectrometer in preparation for a series ...

Recommended for you

Astronomers see pebbles poised to make planets

8 hours ago

A team of astronomers led from St Andrews and Manchester universities today (6 July) announced the discovery of a ring of rocks circling a very young star. This is the first time these 'pebbles', thought ...

Small cosmic 'fish' points to big haul for SKA Pathfinder

8 hours ago

A wisp of cosmic radio waves, emitted before our solar system was born, shows that a new radio telescope will be able to detect galaxies other telescopes can't. The work, led by Dr James Allison of the Commonwealth ...

Gaia produces stellar density map of the Milky Way

9 hours ago

This image, based on housekeeping data from ESA's Gaia satellite, is no ordinary depiction of the heavens. While the image portrays the outline of our Galaxy, the Milky Way, and of its neighbouring Magellanic ...

Hubble view: Wolf-Rayet stars, intense and short-lived

Jul 03, 2015

This NASA/European Space Agency (ESA) Hubble Space Telescope picture shows a galaxy named SBS 1415+437 (also called SDSS CGB 12067.1), located about 45 million light-years from Earth. SBS 1415+437 is a Wolf-Rayet ...

NASA image: Stellar sparklers that last

Jul 03, 2015

While fireworks only last a short time here on Earth, a bundle of cosmic sparklers in a nearby cluster of stars will be going off for a very long time. NGC 1333 is a star cluster populated with many young ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.