Chandra X-ray Observatory

Chandra X-ray Observatory — 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 orbit was achieved after deployment by a built-in propulsion system which boosted the observatory to a high Earth orbit. This 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 kilometers (9,942 miles). The time to complete an orbit is 64 hours and 18 minutes.

The spacecraft spends 85% of its orbit above the belts of charged particles that surround the Earth. Uninterrupted observations as long as 55 hours are possible and the overall percentage of useful observing time is much greater than for the low Earth orbit of a few hundred kilometers used by most satellites.

Extraordinary commitment and precision is required to plan and build telescopes that will be placed in space where they are operated by remote control in a hostile environment of wild temperature swings and hard vacuum, after withstanding the controlled fury of launch. The entire process typically takes many years and creativity is demanded when unexpected changes are imposed. The Chandra observatory was first proposed to NASA in 1976 and funding began in 1977 when NASA’s Marshall Space Flight Center started the definition studies of the telescope.

In 1992, there was a major restructuring of the observatory. NASA decided that in order to reduce cost, the number of mirrors would be decreased from twelve to eight and only four of the six scientific instruments would be used. At this point the planned orbit was changed from low to high Earth orbit to preserve the scientific capability of Chandra.

Teams of scientists, engineers, technicians and managers who work at numerous government centers, 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.




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