The Space Telescope Imaging Spectrograph (STIS) was the Hubble spectrograph that failed in 2004 and was repaired by astronauts in 2009.
STIS was installed during Servicing Mission 2 in February 1997, replacing the Goddard High Resolution Spectrograph and the Faint Object Spectrograph. It works as both a spectrograph and an imaging instrument, observing ultraviolet, visible, and near-infrared light.
On August 3, 2004, a power-supply failure made STIS inoperable. Astronauts restored it during Atlantis’s STS-125 mission, also called Servicing Mission 4, in May 2009. The repair involved replacing failed electronics during a difficult spacewalk.
A common mix-up is confusing STIS with COS, the Cosmic Origins Spectrograph. COS was a newer instrument installed during the same 2009 servicing mission, whereas STIS was the older instrument being repaired. STIS later produced important observations, including the first spectrum of an exoplanet atmosphere.