| 1946: Lyman Spitzer is the first to push for a space-based telescope free of atmospheric limitations in his paper, Astronomical Advantages of an Extra-Terrestrial Observatory. |
| 1969: The National Academy of Sciences' Ad Hoc Committee on the Large Space Telescope, headed by Spitzer, urges NASA to develop an orbital telescope in "Scientific Uses of the Large Space Telescope." |
| 1971: NASA creates the Large Space Telescope Science Steering Group to begin studying the feasibility of a three-meter diameter telescope. |
| 1975: After being invited to join the project, European Space Agency agrees to become involved with the large program. The diameter of the telescope is reduced to 2.4 meters. |
| 1977: Initial designs are refined and the space telescope program officially receives funding from Congress. NASA awards contracts to Perkin-Elmer Corporation for the optics systems and Lockheed Missiles and Space to develop the telescope housing. |
| 1981: Perkin-Elmer completes the telescope's mirror using a computer-controlled laser. A programming glitch that occurred while grinding the mirror would later account for Hubble's blurred images. NASA forms the Space Telescope Science Institute, which becomes a part of the Association of Universities for Research in Astronomy (AURA), to manage the telescope's science program. |
| 1983: The spacecraft is officially named after astronomer Edwin P. Hubble. |
| 1984: Assembly of the optical system completed by Perkin-Elmer Corporation. |
| 1985: Final assembly of the spacecraft completed by Lockheed Missiles and Space Company. |
| 1986: Scheduled for launch in autumn and subsequently delayed by the Challenger disaster earlier that year. |
| April 24, 1990: Launch aboard Discovery on STS-31. Scientists later uncover a spherical aberration in the mirror that leads to slightly blurred images. |
| December, 1993: Servicing mission aboard STS-61 to improve Hubble's image quality by installing corrective optics. The crew also replaces the solar arrays, updates Hubble's computers, and installs the Wide Field and Planetary Camera 2. |
| 1994: Hubble observes pieces of the Comet Shoemaker-Levy 9 plunge into the atmosphere of Jupiter. This is considered to be a once-in-a-millennium collision by astronomers. |
| February, 1997: STS-82 performs a second servicing mission, replacing several of Hubble's parts. |
| 1998: Hubble contributes to research that indicates that the universe's expansion is accelerating by accurately measuring the luminosities of distant stars. The previous prevailing notion was that the Universe's expansion was slowing down.
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| December, 1999: All six of Hubble's gyroscopes replaced by STS-103.
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| March, 2002: Servicing mission by STS-109 replaces the solar arrays for a third time and installs the Advanced Camera for Surveys. |
| 2004: Following the loss of Columbia on reentry in 2003, NASA Administrator Sean O'Keefe evaluates a robotic servicing mission to repair Hubble, ultimately deciding that it would be too costly and the risk too great. The Columbia Accident Investigation Board's recommendation that the Orbiter's underside be visually checked by International Space Station crew, and that the Space Station be used for safe haven if necessary, makes another Shuttle servicing mission unlikely. |
| 2005: NASA Administrator Michael Griffin revisits the decision to cancel a servicing mission and commissions additional studies at Goddard Space Flight Center. |
