The primary mirror of the Hubble Space Telescope (HST) has a spherical aberration, which means that it is not perfectly spherical. This causes light rays that reflect off the primary mirror to be focused at different points depending on their wavelength. This results in images that are blurred and distorted, especially at the edges of the field of view.

The Fix

The spherical aberration of the HST was corrected by installing a corrective optics device called the COSTAR (Corrective Optics Space Telescope Axial Replacement). COSTAR was installed during a servicing mission in 1993 and it successfully restored the HST's ability to produce sharp images.

Other Problems with Hubble

In addition to spherical aberration, the HST has experienced a number of other problems over the years, including:

* Power failures: The HST has experienced several power failures, which have caused the telescope to lose its pointing ability and data collection capabilities.

* Computer problems: The HST has also experienced a number of computer problems, which have caused the telescope to lose data and malfunction.

* Gyroscope failures: The HST has experienced several gyroscope failures, which have caused the telescope to lose its ability to point accurately.

Despite these problems, the HST has been a tremendous success and has revolutionized the way we study the universe. It has made many important discoveries, including the expansion of the universe, the existence of black holes, and the birth of stars and galaxies.