The third in the National Aeronautics and Space Administration’s series of four Great Observatories was deployed from space shuttle Columbia on mission STS-93, ushering in studies of celestial X-ray emissions of greater scope than previously possible.
X-ray astronomy originated with Uhuru,
Unlike visible light, which bounces off silvered mirrors or transmits through transparent glass, X rays focus by grazing off metal mirrors. The Chandra X-Ray Observatory thus incorporated four huge pairs of mirrors in the shape of paraboloids and hyperboloids, which greatly added to the overall telescope length. Chandra is 13.8 meters (45.3 feet) long with its sunshield open and is shaped like a tapered cone with a wide, polygonal instrumentation section at the conical base. Chandra weighs 11.6 metric tons.
At the focal plane, nine meters (thirty feet) behind the mirrors, are a CCD (charged-coupled devices) imaging spectrometer and the high-resolution camera; these instruments produce the spectacular images generated during observations. X rays are focused at this plane into a spot half the width of a human hair, giving Chandra a resolving power twenty to fifty times better than previous X-ray telescopes. In addition, Chandra was outfitted with both a low- and a high-energy transmission grating that can be moved into place behind the mirrors to spread out incident X rays, providing a spectral analysis of these emissions. Chandra runs on just 2.3 kilowatts of electrical power generated by a pair of solar arrays measuring 19.5 meters (sixty-four feet) tip to tip. Power is stored in three banks of batteries. The satellite’s attitude is primarily controlled by momentum transfer in reaction wheels.
A thoroughly unique historical backdrop added to the landmark nature of shuttle mission STS-93 and its delivery of Chandra to orbit. Spaceflight enthusiasts and participants from the early space age converged at Kennedy Space Center in Florida for myriad celebrations of the thirtieth anniversary of the Apollo 11 lunar landing. The recently crowned world champion American women’s soccer team, along with other high-profile women, joined First Lady Hillary Rodham Clinton aboard Air Force One to witness the first launch attempt, this primarily in honor of Eileen M. Collins’s becoming the first American woman to command a crewed space mission.
Also, out at sea, recovery efforts had successfully raised Gus Grissom’s Liberty Bell 7 Mercury spacecraft from the ocean floor; the capsule was found nearly three miles away from where it had rested since July 21, 1961, having sunk shortly after splashdown when Grissom completed America’s second spaceflight. At nearby Titusville, astronauts Wally Schirra and Eugene Cernan joined local dignitaries and space program officials in dedicating a new Apollo park; a bust of President John F. Kennedy delivering the speech proclaiming the national goal of landing a man on the Moon was unveiled. An invitation to dedicate that bust had been extended to John F. Kennedy, Jr., but he decided to attend a family wedding. The plane he was piloting was lost at sea a week before the Chandra launch; he, his wife Carolyn, and her sister perished in that crash. The search for wreckage and bodies shared a media limelight with STS-93 and the anniversary events at Kennedy Space Center.
The space shuttle Columbia’s
A comparative view of Earth’s moon from an optical telescope and an x-ray image from the Chandra instrument. The Chandra data have revealed that X radiation once thought to originate from the Moon actually comes from Earth’s geocorona, the extreme outer atmosphere through which orbiting spacecraft move.
In order to get Chandra to its operational orbit, a solid-fueled upper stage was attached to the satellite. Chandra and its upper stage were spring-ejected from Columbia roughly seven hours into flight. An hour later, that upper stage ignited to boost Chandra to an orbit ranging from 11,000 to 140,000 kilometers (about 6,800 to 87,000 miles) above Earth. In such a location, it could not be serviced as the Hubble Space Telescope has been on several occasions. Along the way to this orbital position, the observatory’s solar panels and antennae unfurled properly.
Chandra had taken up the vast majority of Columbia’s payload bay, and, as a result, STS-93 almost exclusively revolved around Chandra’s deployment; only a few secondary experiments were carried out on Columbia’s middeck area. STS-93 was thus one of the briefest shuttle missions, lasting just under five days. Columbia landed at the Kennedy Space Center runway at 11:20
Earth’s protective and life-sustaining atmosphere permits visible wavelengths and portions of the radio and infrared sections of the electromagnetic spectrum to penetrate and be observed by ground-based telescopes. However, until the advent of the space age, the majority of the infrared, ultraviolet, X-ray, and gamma-ray portions of the spectrum remained undetected. Satellite-based sensors subsequently revealed a wide range of exotic objects in the cosmos and provided clues that greatly expanded our understanding of the nature and evolution of stars, galaxies, and the universe as a whole. To understand any celestial object fully, scientists need to observe its emissions and absorptions across the electromagnetic spectrum. This was the grand purpose of NASA’s Great Observatories program,
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Fabian, A. C., K. A. Pounds, and R. D. Blandford, eds. Frontiers of X-Ray Astronomy. New York: Cambridge University Press, 2004. Contains separate papers provided by a number of researchers generating landmark data with the Chandra Observatory. For the serious student of astrophysics. -
Schlegel, Eric M. The Restless Universe: Understanding X-Ray Astronomy in the Age of Chandra and Newton. New York: Oxford University Press, 2005. Expounds on discoveries made by NASA’s Chandra and the European Space Agency’s Newton-XMM observatories. Provides detailed descriptions, accessible to general readers, of high-energy processes that result in X-ray emissions recorded by these facilities. The author worked on Chandra prior to its launch and provides a detailed developmental history of the observatory’s hardware. -
Unsöld, Albrecht, Bodo Baschek, and W. D. Brewer. The New Cosmos: An Introduction to Astronomy and Astrophysics. 5th ed. New York: Springer, 2005. Serves as an excellent textbook for either advanced high school classes or undergraduate classes in astronomy. Illustrated. -
World Spaceflight News. Twenty-first Century Complete Guide to the Chandra X-Ray Observatory. New York: Progressive Management, 2003. Comprehensive examination of supernovas, pulsars, neutron stars, quasars, and black holes, among others, produced by a spaceflight advocacy group. Includes nearly six thousand pages of text and images in a two-disc CD-ROM set.
Construction of the Keck Telescope Begins in Hawaii
Kamiokande Neutrino Telescope Begins Operation
NASA Launches the Hubble Space Telescope
Astronauts Repair the Hubble Space Telescope
NASA Launches the Solar and Heliospheric Observatory