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        Summary 
        
         
          
           | Description | 
           Hubble Space Telescope Primary Mirror: This photograph shows the Hubble Space Telescope's (HST's) Primary Mirror being ground at the Perkin-Elmer Corporation's large optics fabrication facility. After the 8-foot diameter mirror was ground to shape and polished, the glass surface was coated with a reflective layer of aluminum and a protective layer of magnesium fluoride, 0.1- and 0.025-micrometers thick, respectively. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The Marshall Space Flight Centre had responsibility for design, development, and construction of the HST and the Perkin-Elmer Corporation, in Danbury, Connecticut, developed the optical system and guidance sensors. | 
          
          
           | Date | 
           1 March 1979 | 
          
          
           | Source | 
           NASA Marshall Space Flight Centre Collection (NIX MSFC-7995584) | 
          
          
           | Author | 
           NASA Marshall Space Flight Centre | 
          
          
           Permission ( Reusing this file) | 
           
             NASA 
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         Licensing 
        
         
          
           | Public domainPublic domainfalsefalse | 
          
         
         
          
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           This file is in the  public domain because it was solely created by  NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". (See  Template:PD-USGov,  NASA copyright policy page or  JPL Image Use Policy.) | 
           
            
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           Warnings:
             - Use of  NASA logos, insignia and emblems are restricted per US law  14 CFR 1221.
 
             - The NASA website hosts a large number of images from the  Soviet/ Russian space agency, and other non-American space agencies. These are not necessarily in the public domain.
 
             - Materials based on  Hubble Space Telescope data may be copyrighted if they are not explicitly produced by the  STScI.  See also {{ PD-Hubble}} and {{ Cc-Hubble}}.
 
             - The  SOHO (ESA & NASA) joint project implies that all materials created by its probe are copyrighted and require permission for commercial non-educational use.  
 
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