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 machine "Space Shuttle" was produced by Zaccaria and a 1984 pinball machine "Space Shuttle: Pinball Adventure" was produced by Williams and features a plastic Space Shuttle model among other artwork of astronauts on the play field. The Space Shuttle also appears in a number of flight simulator and space flight simulator games such as "Microsoft Space Simulator", "Orbiter", "FlightGear", "X-Plane" and Space Shuttle Mission 2007. Several Transformers toys were modeled after the Space Shuttle. The U.S. Postal Service has released several postage issues that depict the Space Shuttle. The first such stamps were issued in 1981, and are on display