Astronomers from a half-dozen institutions, including Cornell, will literally be looking at the universe in a new light this week following the launch of NASA's Submillimeter Wave Astronomy Satellite (SWAS) this past Saturday.
The first space-borne observatory dedicated to studying the heavens in submillimeter radiation -- a narrow band of cosmic emission lying between infrared and radio waves on the electromagnetic spectrum -- SWAS will study the conditions that lead to the formation of new star systems, a process now hidden deep within obscuring clouds of dust and gas.
SWAS got a jump-start into space when it was dropped from the belly of a specially modified L-1011 aircraft flown out of Vandenberg Air Force Base, Calif., Saturday evening, Dec. 5, after two previous attempts were aborted due to technical and weather problems. The Pegasus-XL launch vehicle, built by Orbital Sciences Corp., is a three-stage, solid-propellant booster system designed to be carried aloft by the L-1011 aircraft. The rocket, with its satellite observatory payload, was released when the aircraft reached an altitude of about 40,000 feet.
Enabling astronomers to probe deep into the heart of these stellar nurseries, SWAS will gather data on the structure, motions, and nature of the matter that creates new stars.
"Although stars are the basic building blocks of the universe, little detail is known concerning how stars are formed. Even today, this vital process is among the least understood steps in cosmic evolution," said Paul Goldsmith, director of Cornell's National Astronomy and Ionosphere Center (NAIC). "SWAS will give astronomers critical information about conditions in regions that are, or will likely soon be forming stars."
The detectors carried by the SWAS observatory are tuned to the characteristic emission frequencies of five different atoms and molecules, including water and molecular oxygen. These atoms and molecules are important for several reasons. First, they are predicted to be important coolants of the interstellar clouds collapsing to form stars and planets. Second, the detection of these atoms and molecules can provide important, but hitherto missing, information about the composition and chemistry of those clouds. And, finally, knowledge about the abundance of such life-sustaining molecules as water and molecular oxygen in the parent clouds may shed light on how these species are deposited in the rocks and atmospheres of newly forming planets.
Cosmic submillimeter emission cannot be easily studied from the ground -- even at high mountain-top or airborne astronomical observatories -- because of interference from the large quantities of water and molecular oxygen within the Earth's own atmosphere. At an orbital altitude of some 370 miles above Earth, SWAS will have an unobstructed view of the heavens.
The SWAS observatory will orbit the Earth every 97 minutes and will typically observe three to five astronomical objects per orbit.
In addition to principal investigator Gary Melnick of the Harvard-Smithsonian Center for Astrophysics (CfA), the SWAS co-investigators are Alexander Dalgarno, Giovanni Fazio, John Stauffer and Patrick Thaddeus, also of the CfA; Goldsmith and Martin Harwit, of Cornell; Neal Erickson and Ronald Snell, University of Massachusetts; David Koch and David Hollenbach, NASA Ames Research Center; David Neufeld, Johns Hopkins University; and Rudolf Schieder and Gisbert Winnewisser, University of Cologne, Germany.
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