The FOC was constructed by ESA, while the University of California, San Diego and the Martin Marietta corporation built the FOS.The final instrument was the HSP, designed and built at the University of Wisconsin-Madison.. 
A gap in space-Observing capabilities between a decommisSioning of Hubble and the commisSioning of a successor is of major concern to many Astronomers, given the significant Scientific impact of Hst.. 