Hubble Space Telescope scientific merit, did not duplicate proposals made by professionals, and required the unique capabilities of the space telescope. Thirteen amateur astronomers were awarded time on the telescope, with observations being carried out between 1990 and 1997. One such study was "Transition Comets—UV Search for OH". The very first proposal, "A Hubble Space Telescope Study of Posteclipse Brightening and Albedo Changes on Io", was published in "Icarus", a journal devoted to solar system studies. A second study from another group of amateurs was also published in "Icarus". After that time, however, budget reductions at STScI made the support of work by
Space Shuttle of Defense's assistance and refused the request for the spacewalk, and thus the feasibility of scenarios for astronaut repair or rescue by "Atlantis" were not considered by NASA management at the time. NASA retired the Space Shuttle in 2011, after 30 years of service. The Shuttle was originally conceived of and presented to the public as a "Space Truck", which would, among other things, be used to build a United States space station in low earth orbit in the early 1990s. When the U.S. space station evolved into the International Space Station project, which suffered from long delays and design