<p>An engineering backup of the Hubble Space Telescope, on display at the Smithsonian Air and Space Museum in Washington, D.C. 
</p><p>Hubble is a space telescope that put into orbit by a space shuttle in 1990. It has four instruments, which detect light in the ultraviolet, visible, and near infrared spectrums. It is named for astronomer Edwin Hubble.
</p><p>Immediately after Hubble went active, it became apparent that something was seriously wrong with the telescope.  The images it was returning were very fuzzy!!  Engineers quickly determined that Hubble's primary mirror had been ground to the wrong shape: It was too flat at the edges by about 2,200 nanometers.  A commission determined that the device used to measure the exact shape of the mirror (made by a company called Perkin-Elmer) had been incorrectly assembled.  Although two other devices functioned perfectly (and said the mirror was being misaligned), Perkin-Elmer relied only on the badly-assembled main device.
</p><p>Thankfully, the flaw could be corrected.  The Wide Field and the Planetary Camera 2 collected light onto computer chips.  A flaw could be physically put on the chips that would counteract the poorly focused light coming from the Hubble main mirror.  But the other instruments did not collect light this way.  So NASA developed the Corrective Optics Space Telescope Axial Replacement (COSTAR) system. COSTAR was a new mirror which intercepted the light from Hubble's main mirror, then refocused it even further.  In December 1993, a shuttle mission removed Hubble's High Speed Photometer and put the COSTAR in its place.  COSTAR and the purposefully flawed chips worked perfectly!
</p><p>Between 1993 and 2002, four shuttle missions repaired, upgraded, and replaced systems on Hubble.  The fifth and final mission, in 2009, extended Hubble's life until 2014.  Hubble will then shut down.  The successor telescope, the James Webb Space Telescope (JWST), is supposed to be launched in 2018 or later.
</p><p>Hubble was supposed to return to Earth aboard a space shuttle.  But when the entire shuttle fleet was retired in 2011, Hubble was abandoned to the fate of burn-up during re-entry.
</p>
Hubble is due to crash back to Earth in 2025.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/23165290@N00">Tim Evanson</a> from Cleveland Heights, Ohio, USA
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/timevanson/7239238068/">Hubble Space Telescope - Space Hall - Smithsonian Air and Space Museum - 2012-05-15</a>