- 5 years in space


Subrahmanyan Chandrasekhar - the man behind the name

Subrahmanyan Chandrasekhar (1910-1995).

Subrahmanyan Chandrasekhar was one of the foremost astrophysicists of the twentieth century. He was born in Lahore, then a part of British Colonial India, to Sita Balakrishnan and Chandrasekhara Subrahmanya Ayyar in Oct 1910. Trained as a physicist at Presidency College, in Madras, India and at the University of Cambridge, in England, he was one of the first scientists to combine the disciplines of physics and astronomy. Early in his career he demonstrated that there is an upper limit to the mass of a white dwarf star. This limit – now called the Chandrasekhar limit – showed that stars more massive than the Sun would explode or form black holes as they died. A white dwarf is the last stage in the evolution of a star such as the sun. When the nuclear energy source in the centre of a star such as the sun is exhausted, it collapses to form a white dwarf. This discovery is basic to much of modern astrophysics, since it shows that stars much more massive than the sun must either explode or form black holes.

Chandra migrated in 1937 from India to the United States, where he joined the faculty of the University of Chicago, a position he remained at until his death. He and his wife became American citizens in 1953. Chandrasekhar was elected to the Academy only two years after he became a US citizen. He was noted for his work in the field of stellar evolution, and in the early 1930s he was the first to theorize that a collapsing massive star would become an object so dense that not even light could escape it. Although this finding was greeted with some scepticism at the time it was announced, it went on to form the foundation of the theory of black holes, and eventually earned him a shared Nobel Prize in physics for 1983. In addition to his work on star degeneration, Chandrasekhar contributed important theorems on the stability of cosmic masses in the presence of gravitation, rotation, and magnetic fields; this work proved to be crucial for the understanding of the spiral structure of galaxies. From the time he came to the US in 1936 until his death in 1995, Chandrasekhar was affiliated with the University of Chicago and its Yerkes Observatory.

Chandra also developed theories on star atmospheres, black holes, illumination of the sunlit sky, star structures and star mass. In 1983 Chandra was awarded the Nobel Prize in Physics for his work on the physical processes involved in the structure and evolution of stars. Chandra published ten books and served as the editor of the prominent Astrophysical Journal for nineteen years. In 1999, four years after his death in August of 1995, NASA launched Chandra, an x-ray observatory named in honour of Subrahmanyan Chandrasekhar. The observatory studies the Universe in the x-ray portion of the electromagnetic spectrum.

• Chandra flies 200 times higher than Hubble - more than 1/3 of the way to the moon!
   
• Chandra can observe X-rays from clouds of gas so vast that it takes light five million years to go from one side to the other!
   
• During manoeuvres from one target to the next, Chandra slews more slowly than the minute hand on a clock.
   
• At 45 feet long, Chandra is the largest satellite the shuttle has ever launched!
   
• Chandra's resolving power is equivalent to the ability to read a stop sign at a distance of twelve miles.
   
• The electrical power required to operate the Chandra spacecraft and instruments is 2 kilowatts, about the same power as a hair dryer.
   
• The light from some of the quasars observed by Chandra will have been travelling through space for ten billion years
   
• STS-93, the space mission that deployed Chandra, was the first NASA shuttle mission commanded by a woman.
   
• Chandra can observe X-rays from particles up to the last second before they fall into a black hole!!!

The Chandra X-ray Observatory helps astronomers worldwide better understand the structure and evolution of the universe by studying powerful sources of X rays such as exploding stars, matter falling into black holes and other exotic celestial objects. X-radiation is an invisible form of light produced by multimillion degree gas. Chandra provides x-ray images that are fifty times more detailed than previous missions. At more than 45 feet in length and weighing more than five tons, it is one of the largest objects ever placed in Earth orbit by the Space Shuttle.

NASA's Chandra X-ray Observatory, which was launched and deployed by Space Shuttle Columbia on July 23, 1999, is the most sophisticated X-ray observatory built to date.

Chandra is designed to observe X-rays from high-energy regions of the universe, such as the remnants of exploded stars.

The Observatory has three major parts: (1) the X-ray telescope, whose mirrors focus X-rays from celestial objects; (2) the science instruments which record the X-rays so that X-ray images can be produced and analyzed; and (3) the spacecraft, which provides the environment necessary for the telescope and the instruments to work.

Chandra's unusual high Earth orbit., which has the shape of an ellipse, takes the spacecraft more than a third of the way to the moon before returning to its closest approach to the Earth of 16,000 kilometres (9,942 miles). The time to complete an orbit is 64 hours and 18 minutes.

Teams of scientists, engineers, technicians and managers who work at numerous government centres, Universities and corporations have been building and assembling Chandra over the past twenty years. Many of these dedicated men and women have been involved in the project from its inception.

Chandra has begun an exploration of the hot turbulent regions in space with images 25 times sharper than previous X-ray pictures. Chandra can enable astronomers to study the process by which jets of matter are ejected from supermassive black holes in the dense central regions of galaxies.

Chandra's improved sensitivity can make possible more detailed studies of black holes, supernovas, and dark matter and increase our understanding of the origin, evolution, and destiny of the universe.

Text courtesy:

chandra.harvard.edu

chandra.nasa.gov

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