As chairman of the Chandra Science Users Committee -- responsible for decisions on how to use one of the most powerful and expensive instruments ever propelled into space -- University Astronomy Prof. Craig Sarazin will be able to influence the direction of the astronomy community into the 21st century.
The Chandra X-Ray Observatory, named for the acclaimed astrophysicist Subrahmanyan Chandrasekhar, is NASA's newest big-budget project. Chandra is an X-ray telescope that circles the Earth at a high orbit of 87,000 miles above the surface -- about a third of the distance to the moon.
"Chandra is a satellite for looking at the universe with X-rays rather than with optics," Sarazin said.
The Chandra Science Users Committee meets twice yearly and devises a report that is sent to the director of the Chandra Observatory based in Cambridge, Mass.
"We advise NASA and people who run the observatory on how to obtain the best scientific usage out of Chandra," Sarazin said.
Following the media hype of the Hubble Space Telescope, which uses visible light rather than X-rays, NASA's newest space-based telescope promises to be just as revolutionary in its scientific importance.
"The most energetic objects in the Universe emit X-ray radiation," Sarazin said. "Chandra allows us to see the most violent and energetic objects in the universe."
The need for a telescope like Chandra was recognized as early as the 1960's, he said.
He added that clouds of dust and gas often obscure the view of some objects, preventing optical telescopes from gaining a clear picture of them.
"X-rays can penetrate through matter, whereas visual light cannot," Sarazin said.
Shuttled into space July 23, the Chandra X-ray Observatory, at a length of 57 feet and a weight of 20 tons, became the largest and heaviest object ever launched into orbit. The cost of the telescope -- $1.5 billion to build and $2.8 billion including operating costs for five years -- ranks it among the most expensive projects in NASA's history.
Chandra's specifications and early observations already have gone a long way toward justifying its expense.
Chandra is a hundred times more sensitive than any other X-ray telescope ever produced. It can detect X-ray radiation toward the edges of the universe.
"What makes Chandra so revolutionary is that its resolution is so sharp," said Joshua Kempner, College graduate astronomy student.
A revolutionary discovery from the first image photographed by Chandra attests to the telescope's unparalleled clarity. Almost dead center of Cassiopeia-A, a long-studied supernova remnant, lies a tiny white dot that many scientists believe to be a neutron star.
"No one had ever seen that before," Kempner said.
By studying observations made by Chandra, Sarazin and College graduate students Kempner, Jason Moore, Scott Randall and Riccardo Audano, who work with Sarazin, hope to shed light on questions concerning the nature of the universe that have eluded astronomers for decades.
The primary interest of Sarazin and the graduate students working with him is examining galaxy clusters, groups of thousands of galaxies bound together by gravity.
"The highest emitters of energy in the Universe are clusters of galaxies that come together and produce X-ray radiation," Moore said. "That makes Chandra especially useful in making observations of them."
Among the questions that Sarazin hopes to illuminate by his study of galaxy clusters is whether the universe will continue to expand infinitely into the future or whether it eventually will collapse because of the pull of its own gravity.
"Galaxy clusters are large enough that they represent a fair sample of the universe, yet small enough that they remain distinct objects," Sarazin said. "By studying how clusters assemble, we can get a good idea of the structure of the universe as a whole."
Chandra's observations also will assist astronomers in their study of the famed but little-understood objects known as black holes. A Black hole has a gravitational pull so great that even light cannot escape its edges.
"The way in which a black hole produces light is that material falls onto the black hole and produces X-ray radiation," Sarazin said. "With Chandra we hope to be able to peer in and watch the behavior of material closer to the black hole than we've ever seen before"
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