Chandra X-ray Observatory: Expedition to Unravel a Marvelous Universe

Chandra X-ray Observatory

NASA’s Chandra X-Ray Observatory (CXO) is a telescope specially designed to detect X-ray emission from all sources of high energy in the universe that are invisible to the human eye. This great observatory was formerly known as the Advanced X-Ray Astrophysics Facility (AXAF) and has joined the Hubble Space Telescope (HST) and the now-defunct Compton Gamma-Ray Observatory (CGRO). It provides unprecedented capabilities for sub-arcsecond imaging, spectrometric imaging, and high-resolution dispersive spectroscopy, enabling it to be able to observe a wide variety of high-energy phenomena. It looks at an all-encompassing range of astronomical objects including exploded stars, clusters of galaxies, matter around black holes, quasars and supernovas.

Chandra: Foremost of all “Great Observatories”

The observatory was first proposed in 1976, and work proceeded by the 1980s and reconfigured in 1992 (by reducing mirrors and instruments) to make it more cost-effective and suitable to launch by shuttle. It was launched and deployed by Space Shuttle Columbia on July 23, 1999, and was named the Chandra X-ray Observatory, in honor of the late Indian-American Nobel laureate, Subrahmanyan Chandrasekhar, who was widely regarded as one of the most brilliant astrophysicists of the twentieth century. When finalized, it was in an elliptical orbit around the Earth ranging anywhere from about 9,940 miles (16,000 km) to 82,650 miles (133,000 km) from Earth. Since X-rays are absorbed by Earth’s atmosphere, CXO orbits above it up to an altitude of 86,500 miles (139,000 km) in space and analyzes very detailed images or spectra of the cosmic source.

Figure 01: Deployment of the Chandra X-ray Observatory

It carries four very sensitive mirrors nested inside each other and focuses the energetic X-rays which strike the inside of the hollow shells onto electronic detectors at the end of the 9.2 m (30-ft.) optical bench. The Observatory has three major parts namely, the X-ray telescope whose mirrors focus X-rays from celestial objects; the science instruments which record the X-rays; and the spacecraft which provides the environment necessary for the telescope and the instruments to work. Providing scientific data to the international astronomical community in response to scientific proposals for its use, the CXO is the most sophisticated X-ray observatory built to date.

Chandra X-ray Observatory Specifications
Figure 02: Specifications of the Chandra X-ray Observatory

Exciting Discoveries through Time

CXO has imaged the spectacular, glowing remains of exploded stars, and taken spectra showing the dispersal of elements. It has also observed the region around the supermassive black hole in the center of our Milky Way and found black holes across the universe. Furthermore, it has contributed to both dark matter and dark energy studies, tracing the separation of dark matter from normal matter in the collision of galaxies in a cluster. The observatory has helped scientists to glimpse the universe in action by watching colliding galaxies, a black hole with cosmic hurricane winds, and a supernova turning itself inside out after an explosion. One of its first pictures was of Cassiopeia A, the remnants of a star that exploded in a supernova.

Later that year, CXO was able to find the elements in the gas surrounding the star and those findings included sulfur, silicon, and iron that blasted out from the star’s interior. Another of its early targets was the Crab Nebula, which showed – for the first time – a ring circling a pulsar star in the center of the nebula. Furthermore, regular updates appeared talking about the telescope’s investigations; X-ray emanating stars embedded in the Orion Nebula, a galaxy growing by gobbling up its neighbors, and evidence of baby stars.

Other important discoveries supported by observations from Chandra are; finding much more cool gas than expected spiraling into the center of the Andromeda Galaxy, seeing the first X-ray emission from the supermassive black hole – Sagittarius A, observing pressure fronts for the first time in Abell 2142 where clusters of galaxies are merging, detecting X-ray emissions from Pluto, and the first detection of X-rays from a Kuiper belt object. As its mission goes on, CXO will continue to discover startling new science about our high-energy universe.

20 Years of the Chandra Observatory
Figure 03: 20 Years of Space Observation through the Chandra X-ray Observatory

NASA’s Flagship Mission for X-ray Astronomy

Chandra’s capability for high-resolution imaging enables detailed high-resolution studies of the structure of extended X-ray sources, including SNRs, astrophysical jets, and hot gas in galaxies and clusters of galaxies. Moreover, its capability for spectrometric imaging allows studies of structure, not only in X-ray intensity but also in temperature and chemical composition as well. It is important to note that, through the observations with Chandra, most of the exciting topics regarding contemporary astrophysics are widely addressed. Throughout its years of performance and operation, Chandra X-Ray Observatory has played a pivotal role in revealing the mysteries of the invisible universe, and the results are serving to usher in a new age of astronomical and astrophysical discoveries.


  1. Chandra x-ray Observatory – NASA’s flagship x-ray telescope. Chandra X-ray Observatory.
  2. Howell, E. (2018, June 15). Chandra space telescope: Revealing the invisible universe.
  3. Weisskopf, M. C., Brinkman, B., Canizares, C., Garmire, G., Murray, S., & Van Speybroeck, L. P. (2002). An overview of the performance and scientific results from the Chandra x‐Ray observatory. Publications of the Astronomical Society of the Pacific, 114(791), 1–24.

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