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.. 
Ní ọdún 1980, a gbàá sílé ìwé Yunifásítì ti Nàìjíríà, Nsukka, òṣì gba àmì-ẹ̀yẹ nínú ìmọ̀ Philosophy ní ọdún 1984.. 