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 program from the two destroyed orbiters. The Space Shuttle program was extended several times beyond its originally envisioned 15-year life span because of the delays in building the United States space station in low Earth orbit—a project which eventually evolved into the International Space Station. It was formally scheduled for mandatory retirement in 2010 in accord with the directives President George W. Bush issued on January 14, 2004 in his Vision for Space Exploration. A$2.5 billion spending provision allowing NASA to fly the Space Shuttle beyond its then-scheduled retirement in 2010 passed the Congress in April 2009, although neither NASA nor