NASA Launches the Chandra X-Ray Observatory Summary

  • Last updated on November 10, 2022

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.

Summary of Event

X-ray astronomy originated with Uhuru, Uhuru (spacecraft) or the Small Astronomy Satellite Small Astronomy Satellite I (SAS-1), which operated in Earth orbit from December, 1970, to March, 1973. Uhuru (Swahili for “freedom”) performed the first comprehensive sky survey in energies ranging from 2 to 20 kiloelectron volts (keV); a typical medical X ray usually involves 50 keV energy irradiation. Uhuru data identified 339 X-ray sources in binary star systems, supernova remnants, a special class of galaxies referred to as Seyfert galaxies, and galaxy clusters. The data opened up a new area of astrophysics and helped pose questions that scientists would eventually answer by using the Chandra X-Ray Observatory. National Aeronautics and Space Administration;Chandra X-Ray Observatory[Chandra X Ray Observatory] Chandra X-Ray Observatory[Chandra X Ray Observatory] X-ray astronomy[X ray astronomy] Telescopes;Chandra X-Ray Observatory[Chandra X Ray Observatory] [kw]NASA Launches the Chandra X-Ray Observatory (July 23, 1999) [kw]Launches the Chandra X-Ray Observatory, NASA (July 23, 1999) [kw]Chandra X-Ray Observatory, NASA Launches the (July 23, 1999) [kw]X-Ray Observatory, NASA Launches the Chandra (July 23, 1999) [kw]Observatory, NASA Launches the Chandra X-Ray (July 23, 1999) National Aeronautics and Space Administration;Chandra X-Ray Observatory[Chandra X Ray Observatory] Chandra X-Ray Observatory[Chandra X Ray Observatory] X-ray astronomy[X ray astronomy] Telescopes;Chandra X-Ray Observatory[Chandra X Ray Observatory] [g]North America;July 23, 1999: NASA Launches the Chandra X-Ray Observatory[10410] [g]United States;July 23, 1999: NASA Launches the Chandra X-Ray Observatory[10410] [c]Astronomy;July 23, 1999: NASA Launches the Chandra X-Ray Observatory[10410] [c]Spaceflight and aviation;July 23, 1999: NASA Launches the Chandra X-Ray Observatory[10410] [c]Science and technology;July 23, 1999: NASA Launches the Chandra X-Ray Observatory[10410] Collins, Eileen M. Ashby, Jeffrey S. Hawley, Steven A. Tognini, Michel Coleman, Catherine G. Wojtalik, Fred S. Hefner, Keith Wiesskopf, Martin C. Chandrasekhar, Subrahmanyan

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 Columbia (space shuttle) first launch attempt halted seven seconds before scheduled liftoff because of a false indication of hydrogen gas buildup within the vehicle. A second attempt was scrubbed because of nearby thunderstorm activity. Then, on July 23, 1999, at 12:31 a.m. eastern standard time (EST), the area around Kennedy Space Center lit up as bright as day while Columbia’s solid rocket boosters and shuttle main engines illuminated the sky, and the vehicle arced out over the Atlantic Ocean toward orbit. Just moments after liftoff, a fuel cell electrical power anomaly momentarily provided additional drama to this launch. Also, a hydrogen leak in the orbiter’s main propulsion system occurred during ascent. Nevertheless, Columbia reached orbit nine minutes after liftoff. The shuttle’s initial orbit was eleven kilometers (6.8 miles) lower than planned. However, that was easily corrected with subsequent thruster firings, and Columbia attained the desired orbit for the Chandra deployment.

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.

(Optical: Robert Gendler; X-ray: NASA/CXC/SAO/J. Drake et al.)

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 p.m. EST on July 27.

Significance

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, Great Observatories program which included the Hubble Space Telescope (visible, infrared, and ultraviolet wavelengths), launched in 1990; the Compton Gamma Ray Observatory (gamma radiation), launched in 1991; the Chandra X-Ray Observatory (X-ray radiation); and the Spitzer Space Telescope (infrared wavelengths), launched in 2003. These four observatories would provide comprehensive examinations of astrophysical processes and make unprecedented new discoveries. Compton was purposely rammed into Earth’s upper atmosphere to be destroyed after its mission was completed in 2000, but Hubble, Chandra, and Spitzer continued to provide coordinated research into the twenty-first century. National Aeronautics and Space Administration;Chandra X-Ray Observatory[Chandra X Ray Observatory] Chandra X-Ray Observatory[Chandra X Ray Observatory] X-ray astronomy[X ray astronomy] Telescopes;Chandra X-Ray Observatory[Chandra X Ray Observatory]

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">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.
  • citation-type="booksimple"

    xlink:type="simple">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.
  • citation-type="booksimple"

    xlink:type="simple">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.
  • citation-type="booksimple"

    xlink:type="simple">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.

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