Chandra Finds its Place in the Sky

American x-ray astronomers finally have a telescope of their own. This morning, the Space Shuttle Columbia safely deployed the $2.8 billion Chandra X-ray Observatory into the orbit from which it is designed to study the universe for at least 5 years. In the next 2 weeks, its mirrors' doors will open and its instruments will start recording x-rays from objects all the way back to the beginning of the universe, producing pictures sharper than the best optical telescopes on Earth.

Columbia's launch was delayed twice this week, because of a faulty sensor and a thunderstorm over Cape Canaveral. But astronomers had been waiting much longer; Chandra has a record of "de-scoping" (in NASA's jargon), missed deadlines, software bugs, and stuck doors (ScienceNOW, 20 January 1999 and 28 April 1999). And scientists can only hope that nothing else goes awry: Because of its high orbit, astronauts will not be able to fix Chandra once it is in space.

But if all goes well, the observatory, named for the late astrophysicist Subrahmanyan Chandrasekhar, is likely to be the revelation to x-ray astronomy that its sister space telescope, the Hubble, has been to optical astronomy. With Chandra, astronomers can take a close look at some of the most turbulent parts of the cosmos. X-rays--undetectable on Earth because they are blocked by the atmosphere--are spawned by supernova explosions, material being dragged into supermassive black holes, and clouds of fiery intergalactic gas.

Because X-rays penetrate ordinary glass mirrors rather then reflecting from them, Chandra's mirrors consist of sets of nested glass cans arranged so that x-rays graze them rather than strike them head-on. Chandra's mirrors are larger, smoother, and lighter than those in previous x-ray telescopes. "Chandra's got the best x-ray mirrors that have ever been made," boasts Stephen Murray of the Harvard-Smithsonian Center for Astrophysics, principal investigator for Chandra's high-resolution camera. That camera is 20 times more sensitive than anything previous; an accompanying imaging spectrograph has a resolution eight times finer.

Once Chandra starts observing, says Riccardo Giacconi, who is generally acknowledged to be the father of x-ray astronomy and now directs Associated Universities Inc., "I'll be so happy. I'll play the old man and bless everybody in sight."

Posted in Space