The Chandra X-ray Observatory is a space telescope that searches for x-ray sources in the universe. The Hubble Space Telescope, Spitzer Space Telescope, and Compton Gamma Ray Observatory are all part of NASA’s Great Observatories program. The Chandra X-ray Observatory is named after Subrahmanyan Chandrasekhar, an Indian-American physicist who discovered the mass limit for white dwarfs to become neutron stars.
The idea for a space telescope was first proposed in the 1940s, just after WWII ended. It wasn’t until the Hubble Space Telescope was launched in 1990 that this was realized. Chandra, the third of the Great Observatories to be operational, was launched in 1999. Chandra is in a unique position to do x-ray astronomy because the majority of x-rays are absorbed by the atmosphere.
Energy-dense astronomical objects and phenomena, such as black holes, neutron stars, and supernovae, produce a lot of X-rays. Chandra has looked into the cores of a number of supernova remnants (planetary nebulae) and found the compact objects that remain, which are black holes or neutron stars. Sagittarius A*, a supermassive black hole at the center of the Milky Way galaxy, has been observed emitting x-rays.
Although this is still up for debate, Chandra may have discovered quark stars, which are even more compact and dense than neutron stars (which are only the size of a city but contain the mass of an entire star). Chandra has contributed to the confirmation of the existence of so-called “dark matter” — invisible matter that is only observed indirectly through its gravitational influence on visible matter — by observing collisions between galactic superclusters. It has detected x-ray emissions from material in protoplanetary discs orbiting far-off stars, providing information about how our solar system formed.
The Chandra satellite has a mass of 4,800 kg (10,600 lb) and orbits the Earth every 64.3 hours in a highly eccentric orbit averaging 10,000 km above the surface. The craft’s diameter is 1.2 meters (3.9 ft).