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Description of Driving Event:

The Hubble Space Telescope did not perform to the requirements of the contract. A spherical aberration was attributed to the spacing between the field lens and the lower mirror of the reflective null corrector. Note that the reflective null corrector is not a part of the HST but is special test equipment used to verify the curvature of the primary mirror, and to aid in the shaping of the telescope mirrors. It was concluded that the problems would likely have been discovered by quality assurance and design oversight if these functions had been conducted in acccordance with the product assurance plan. It was decided to depart from the plan and exclude quality oversight (with the consent of QA) in some areas. There were other problems, which were not as drastic as the spherical aberration which probably would have been discovered also. These problems led to considerable embarrassment to NASA, expenditure of additional funds to determine the cause and plan for on-orbit repair, and a reduced scientific return.