Your car needs a tune-up; so you take it to your mechanic for servicing. Engineers and scientists designed the Hubble Space Telescope with the same principle in mind. When a component breaks or a more technologically advanced instrument becomes available, astronauts install the new equipment using wrenches, screwdrivers and power tools during periodic servicing missions. Servicing missions have occurred in 1993, 1997, 1999, 2002 and 2009.
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