Editing Hubble Space Telescope (section)

=== Servicing Mission 2 ===
{{Main|STS-82}}
[[File:Hubble Space Telescope (27946391011).jpg|thumb|Hubble as seen from ''Discovery'' during its second servicing mission]]

Servicing Mission 2, flown by ''Discovery'' in February 1997, replaced the GHRS and the FOS with the [[Space Telescope Imaging Spectrograph]] (STIS) and the [[Near Infrared Camera and Multi-Object Spectrometer]] (NICMOS), replaced an Engineering and Science Tape Recorder with a new Solid State Recorder, and repaired thermal insulation.<ref>{{cite web |url=http://hubble.nasa.gov/missions/sm2.php |title=Servicing Mission 2 |publisher=NASA |access-date=April 26, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080419153631/http://hubble.nasa.gov/missions/sm2.php <!--Added by H3llBot--> |archive-date=April 19, 2008}}</ref> NICMOS contained a [[heat sink]] of solid [[nitrogen]] to reduce the [[thermal noise]] from the instrument, but shortly after it was installed, an unexpected [[thermal expansion]] resulted in part of the heat sink coming into contact with an optical baffle. This led to an increased warming rate for the instrument and reduced its original expected lifetime of 4.5 years to about two years.<ref name="NICMOStemp">{{cite web |url=http://www.stsci.edu/hst/nicmos/performance/temperature |title=NICMOS Thermal History |publisher=STScI |access-date=April 26, 2008 |archive-date=May 24, 2012 |archive-url=https://archive.today/20120524183957/http://www.stsci.edu/hst/nicmos/performance/temperature |url-status=live }}</ref><!--This reference only generally supports these two sentences, and does not give numbers such as the expected lifetime figures stated here.-->