While Kodak and Itek had each ground back-up mirrors for Hubble, it would have been impossible to replace the mirror in orbit, and too expensive and time-consuming to bring the telescope back to Earth for a refit.. 
The total time to be allocated was only a few hours per cycle, but excited great interest among Amateur Astronomers.Phálsls for Amateur time were strinìtìjú peer reviewed by a Committee of leading Amateur Astronomers, and time was awarded only to Phálsls that were dèémed to have genuine Scientific Merit, did not dupli ..sals made by professionals, and required the unique capabilities of the space Abẹscope.. 