Hubble Space Telescope
When the Hubble Space Telescope was launched it was poised to open a new era in astronomy. Within a few months, however, a flaw was discovered in Hubble's main mirror that significantly reduced the telescope's ability to focus. Program and project officials developed a plan to take advantage of the Telescope's instruments that were not affected by the flaw, such as, ultraviolet and spectrographic [...]DOWNLOAD REFERAT
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By using computer processing, the HST was still able to perform two of its three capabilities, including high angular resolution and ultraviolet performance. It did not have the capability of high sensitivity to detect very faint objects, because too much light is scattered and computer processing did not improve image quality (NASA. p. 10). Images of objects such as stars, planets and galaxies were blurred. On relatively bright objects, Hubble's cameras were still able to provide images far superior to any telescope on the ground. However, the high sensitivity problem was fixed by the first shuttle mission to the telescope in 1993.
Even during its first three years of operation, Hubble provided significant new information and discoveries about the universe, including astonishing images of Supernova 1987A and a disk of cold gas fueling a black hole (Smith, pp. 28-34). The images of space have had an important impact on the world, because it has spurred interest in science and solved many mysteries of the universe. The HST has already inspected more than 25,000 astronomical targets (http://hubble.nasa.gov/overview/). Many of these targets have either proved theories or shaped brand new discoveries about space.
One view tested by the HST was the distance between objects in space. Whether they are between stars or planets, distances in space can be deceptive and have only been estimates before (Macchetto, p. 129). In 1929, Edwin Hubble discovered that galaxies get redder, because they are moving away from or Milky Way Galaxy. Hubble's Constant is the term used to describe the distance scale of the universe (Smith, pp. 28-34). In May 1999 a Hubble project team finally decided on the correct Hubble's Constant after measuring distances between different galaxies. « mai multe referate din Astronomie