The flaw in with observing distant object using ground-based telescopes is that the light must pass through the atmosphere. In addition to clouds and the weather, the atmosphere is a "boiling" place -- there are dust particles, rising warm air currents, falling cold air currents, and water vapor. All of these factors blur images of the stars and hinder ground-based telescopes.
In 1946, the astrophysicist Dr. Lyman Spitzer (1914-1997) proposed that a telescope placed in space or earth-orbit had the possibility to improve the clarity of images, of even farther-off objects, than any ground-based telescope. This was a preposterous idea because no one had yet launched anything, let alone a rocket into outer space. As the U.S. space program grew and improved in the 1960s and 1970s, Dr. Spitzer lobbied NASA and Congress to produce a space telescope. In 1975, the European Space Agency (ESA) and NASA began designing and building the new space based telescope. In 1977, Congress approved funding for the space telescope, and NASA named Lockheed Martin as the prime contractor throughout its production. In 1983, the telescope was named after the famed American astronomer Edwin Hubble, whose observations of many stars in distant galaxies confirmed that the universe was constantly expanding and fueled the "Big Bang" theory’s reputation. The Hubble Space Telescope took 8 years until completion, held five scientific instruments, had more than 400,000 individual parts and had more than 26,000 miles of electrical wiring. The telescope was said to be 50 times more precise than ground-based telescopes, with a 10 times higher resolution. After a long delay due to the Challenger explosion, the telescope was sent into earth-orbit in 1990.
Almost immediately after it was deployed, astronomers found that they could not focus the telescope. They found that the main mirror had been made incorrectly at the Perkin-Elmer Corporation's factory. Although the imperfection in the mirror was smaller than one-fiftieth the size of a human hair, it caused the telescope to produce fuzzy, blurred images.
Scientists produced a replacement outer lens named COSTAR (Corrective Optics Space Telescope Axial Replacement) to correct the defect in the mirror. COSTAR was made of several smaller mirrors that would gather the light from the flawed mirror, correct the problem and send the corrected image to the instruments at the correct place on the mirror.
COSTAR was a great success and improved the images taken greatly. However, all new equipment has built in correction for the defect and it is no longer needed.