Chandra X-ray Observatory

The Chandra X-ray Observatory is a space telescope launched on STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, enabled by the high angular resolution of its mirrors. Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes; therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64 hour orbit, and its mission is ongoing as of 2012.

Chandra Observatory is the third of NASA's four Great Observatories. The first was Hubble Space Telescope; the second was the Compton Gamma Ray Observatory, launched in 1991; and the last is the Spitzer Space Telescope. Of the four, Compton ended in 2000 and the other three continue. Chandra has been described as being as revolutionary to astronomy as Galileo's first telescope.

It was named in honor of the Nobel-prize winning Indian-American astrophysicist Subrahmanyan Chandrasekhar who worked for University of Chicago from 1937 until he died in 1995. He was known for determining the maximum mass for white dwarfs. "Chandra" means "moon" in Sanskrit. Before 1998, it was known as AXAF, the Advanced X-ray Astrophysics Facility. AXAF was assembled and tested by TRW (now Northrop Grumman Aerospace Systems) in Redondo Beach, California.