Although the Hubble Space Telescope has only been orbiting since 1990, it represents the culmination of many years of planning and advocacy. The process to get the telescope to the place where it is today was a long one, with unexpected hurdles thrown in along the way.
The idea for an orbiting telescope predated the Hubble by decades. Astronomers are familiar with the influences that the atmosphere has on visible and invisible electromagnetic waves, and as astronomers began to reach the limits of terrestrial optical telescopes the natural solution was to get the telescopes away from the atmosphere. In some cases, this meant bringing telescopes to the mountains, such as the Mauna Loa observatory in Hawaii.
A second line of thought was more ambitious: place a telescope in orbit outside the influence of the atmosphere entirely. An early advocate, Professor Lyman Spitzer, began organizing support for such a telescope in the 60s as the space age dawned. After some internal deliberation, NASA agreed and funding was approved for the creation of what would be called the Hubble Space Telescope.
The project faced setbacks immediately. The assembly of the telescope itself faced delays throughout the early 1980s, and then when the system was finally ready for launch, the Challenger Disaster grounded all space shuttle flights, including the planned launch of the Hubble.
When flights resumed, other priorities competed with the telescope and it was not until 1990 that the shuttle Discovery finally delivered it to orbit. Almost immediately, NASA discovered a design flaw that led to images being less clear and precise than had been hoped. This was the result of the edges of one of the mirrors being ground too flat. A service mission was already scheduled for 1993, and replacement optical pieces were installed on that mission, one of the most successful demonstrations of the shuttle program in the 1990s.
Additional service missions were performed in 1997, 1999, and 2002. Each servicing mission serves as a chance to repair and replace items on the telescope and to upgrade the various components. The telescope is actually more accurately described as a system of telescopes covering many different areas of the electromagnetic spectrum. With the Columbia disaster of 2003, and the decision to retire the space shuttle fleet, the future of the Hubble is in doubt. Post-Columbia missions had to be prioritized, with a heavy emphasis on missions to the International Space Station not only for the purposes of completing the station, but also for the safety that a rendezvous with the ISS provides for the shuttle occupants. Although the National Academy of Sciences recommended one last shuttle service mission before the shuttle is retired, that service mission appears to be unlikely to occur.
Hubble still has many good years ahead of it, but without additional upgrades it will eventually be overcome by other technology. At twenty years and still going strong, the program is one of the longest running and most successful NASAS programs. In 2014 NASA intends to launch the James Webb Space Telescope which will represent the state of the art in extra-atmospheric telescopy, bringing the era of the Hubble to a close.
Sources:
G Okolski, A Brief History of the Hubble Space Telecscope, http://history.nasa.gov/hubble
http://www.jwst.nasa.gov/
http://www.nasa.gov/hubble/
