However, the other instruments lacked any intermediate surfaces that could be figured in this way, and so required an external correction device.The Corrective Optics Space Telescope Axial Replacement (COSTAR) system was designed to correct the spherical aberration for light focused at the FOC, FOS, and GHRS.. 
When launched, the Storage tórúkọ were old-fashioned Reel-to-Reel àrùnd recorders, but these were replaced by solid state information Storage coal during Servicing missions 2 and 3a.. 