Which NASA space observatory, launched in 1999, studies the universe in X-rays?

The Chandra X-ray Observatory, launched in 1999, studies the universe in X-rays.

NASA launched Chandra on the Space Shuttle Columbia on July 23, 1999. Its highly elliptical orbit carries it far beyond low-Earth orbit, allowing long observations without the interruptions that would occur during frequent passages through Earth’s shadow.

Chandra’s X-ray vision reveals extremely hot and energetic objects, including supernova remnants, black-hole accretion disks, galaxy clusters, and neutron stars. Its mirrors use grazing-incidence optics because ordinary telescope mirrors would absorb incoming X-rays rather than focus them.

Chandra is part of NASA’s Great Observatories program. Hubble primarily observes visible, ultraviolet, and near-infrared light, while Spitzer focused on infrared astronomy and Compton studied gamma rays, so these observatories are not interchangeable.