Hubble Space Telescope

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Hubble Space Telescope as seen from the Space Shuttle Discovery on mission STS-82.

The Hubble Space Telescope is an American space probe in Low-Earth orbit (about 350 miles high) that is used to study and image celestial objects. It is operated by NASA's Goddard Space Flight Center and the Space Telescope Science Institute. The telescope was launched April 25, 1990 and began operations soon thereafter.


After launch, it was found that all of the images from the telescope were out of focus. An investigation found that the primary mirror of the telescope had been ground to the wrong radius, preventing the telescope from properly focusing. In December, 1993, the Space Shuttle Endeavor, during mission STS-61, captured the telescope and added a lens that corrected the defect in the primary mirror. Since then, the Hubble Space Telescope has been an invaluable tool to astronomers.

Hubble has a resolution of just less than 0.1 arcsec in red light.[1] Its main imaging camera has 16 million pixels.

The current mission of the telescope was recently extended by NASA. On January 17, 2004, primarily due to the recent Colombia shuttle accident and the perceived risk of shuttle flights, NASA announced that the final servicing mission to the Hubble Space Telescope would not be funded. Scientists around the world and members of congress put pressure on NASA to reconsider, and on October 31, 2006, NASA announced it would go ahead with a Hubble Space Telescope service mission in 2008. This fourth mission to Hubble cost $1 billion and should effectively extend the life of the telescope by another decade.

The telescope is named after astronomer Edwin Hubble whose observations of galaxies led him to the discovery that the universe is expanding.

The total cost of Hubble to NASA so far has been about $9 billion.[2]

The Hubble has a 94-inch mirror. Earth-based telescopes with three times the diameter cost only 2% as much, but are affected by distortions caused by the atmosphere. Astronomers hope that new methods of adaptive optics will improve the resolution of earth-based telescopes, because funding on the scale of Hubble is difficult to achieve.

Hubble's successor will be the James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope, scheduled for launch in 2014. Its mirror will be 6.5 meters.[3]


The Hubble Ultra Deep Field is a picture taken by Hubble Telescope's Advanced Camera for Surveys (ACS) and the Near Infrared Camera and Multi-object Spectrometer (NICMOS) of an "empty area" one tenth the diameter of a full moon when viewed from Earth. The 11.5 square arc minute area is equivalent to a grain of sand held at arm's length. Taken over a period of almost 11 days, the picture required 400 orbits around Earth and 800 exposures, which is equivalent to approximately 1 million seconds of exposure time. With an estimated 10,000 galaxies in this image, nearly every speck of light is an entire galaxy or group of galaxies.

Other images

See also


External links


  1. One arcsec is 1/3600 of a degree.
  2. Dennis Overbye, "One Last Ride to the Hubble," New York Times Dec 4, 2007
  3. See The James Webb Space Telescope