The Hubble Space Telescope and accessing its archives.

Edwin Hubble was an American astronomer whose ideas profoundly changed the understanding of the universe. He found that the galaxies were moving away from each other and came up with a mathematical description; now know as the Hubble’s law. In his honor, NASA launched an observatory called the Hubble Space Telescope.
Observatories on Earth have distortions due to atmospheric diffraction. In order to over come this, a telescope in space was necessary. Hubble Space Telescope was on Discovery’s payload and was deployed into low Earth orbit in the year 1990. The telescope costed $2.5 billion. Within weeks since launch, the returned images showed that there were serious problems with the optical system. Though the first images appeared to be sharper than those of ground-based telescopes, Hubble failed to achieve a final sharp focus and the best image quality obtained was drastically lower than expected.
Analysis of the flawed images showed that the cause of the problem was that the primary mirror had been ground to the wrong shape. Although it was probably the most precisely figured mirror ever made, with variations from the prescribed curve of only 10 nanometers. NASA and the telescope became the butt of many jokes. Astronomers immediately began to seek potential solutions to the problem that could be applied at the first servicing mission.
Working backwards from images of point sources, a new optical component with exactly the same error but in the opposite sense was decided to be added at the servicing mission, effectively acting as “spectacles” to correct the spherical aberration. The telescope had always been designed so that it could be regularly serviced, but after the problems with the mirror came to light, the first servicing mission assumed a much greater importance, as the astronauts would have to carry out extensive work on the telescope to install the corrective optics. The seven astronauts selected for the mission were trained intensively in the use…

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