Chandra X-ray Observatory (CXO)
One of NASA's Great Observatories in Earth orbit, launched in July 1999, and named after S. Chandrasekhar. It was previously named the Advanced X-ray Astrophysics Facility (AXAF).
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 wasHubble Space Telescope; second the Compton Gamma Ray Observatory, launched in 1991; and last is the Spitzer Space Telescope. Of those four, three continue; Compton ended in 2000. 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 physicist S. 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.
Source: wikipedia, NASA