The Chandra X-ray Observatory captures X-ray images and measures spectra of many high-energy cosmic phenomena. Unlike Hubble, its sister "Great Observatory," Chandra has a highly elliptical orbit that takes it 1/3 of the way to the Moon. This orbit allows Chandra to observe continuously for many hours at a time, but makes it unreachable by the Space Shuttle, which was used to launch it back in 1999.
