Editing Solar Maximum Mission (section)

== Failure and repair ==
[[File:Capturing the Solar Maximum Mission satellite.jpg|thumb|upright=1.0|left|Astronaut [[George Nelson (astronaut)|George Nelson]] attempts to capture the ''Solar Maximum Mission'' satellite during [[STS-41-C]].]]
The white-light coronagraph/polarimeter (C/P) took coronal images for about six months from March 1980 before suffering an electronics failure in September that prevented operation.{{r|hao-smm}}

In November 1980, the second of four fuses in SMM's [[Spacecraft attitude control|attitude control]] system failed, causing it to rely on its [[magnetorquers]] in order to maintain attitude. In this mode, only three of the seven instruments on board were usable, as the others required the satellite to be accurately pointed at the Sun. The use of the satellite's magnetorquers prevented the satellite from being used in a stable position and caused it to "wobble" around its nominally sun-pointed attitude.{{r|STS-41C-pk}} SMM was left in standby mode for 3 years.{{r|hao-smm}}

The first orbiting, uncrewed satellite to be repaired in space, SMM was notable in that its useful life compared with similar [[spacecraft]] was significantly increased by the direct intervention of a crewed space mission. During [[STS-41-C]] in April 1984, the [[Space Shuttle Challenger|Space Shuttle ''Challenger'']] rendezvoused with the SMM, astronauts [[James van Hoften]] and [[George Nelson (astronaut)|George Nelson]] attempted to use the [[Manned Maneuvering Unit]] to capture the satellite and to bring it into the orbiter's payload bay for repairs and servicing. The plan was to use an astronaut-piloted Maneuvering Unit to grapple the satellite with the Trunnion Pin Attachment Device (TPAD) mounted between the hand controllers of the Maneuvering Unit, null its rotation rates, and allow the Shuttle to bring it into the Shuttle's payload bay for stowage. Three attempts to grapple the satellite using the TPAD failed. The TPAD jaws could not lock onto Solar Max because of an obstructing grommet on the satellite not included in its blueprints.

This led to an improvised plan which nearly ended the satellite's mission. The improvisation had the astronaut use his hands to grab hold of a solar array and null the rotation with a push from the Maneuvering Unit's thrusters. Instead, this attempt induced higher rates and in multiple axes; the satellite was tumbling out of control and quickly losing battery life. SMM Operations Control Center engineers shut down all non-essential satellite subsystems and with a bit of luck were able to recover the satellite minutes before total failure. The ground support engineers then stabilized the satellite and nulled its rotation rates for capture with the [[SRMS|Shuttle's robotic arm]]. This proved to be a much better plan. The satellite had been fitted with one of the arm's [[grapple fixture]]s so that the robotic arm was able to capture and maneuver it into the shuttle's payload bay for repairs.{{r|STS-41C-pk}}

During the mission, the SMM's entire attitude control system module and the electronics module for the coronagraph/polarimeter instrument were replaced, and a gas cover was installed over the X-ray polychromator.{{r|STS-41C-pk}} Their successful work added five more years to the lifespan of the satellite. The mission was depicted in the 1985 [[IMAX]] movie ''[[The Dream Is Alive]]''.