Servicing Mission 3A (SM3A)

In November 1999, the fourth of Hubble’s six gyros needed for safely turning and locking onto observation targets failed, leading the telescope to enter safe mode and stop making observations. Rather than wait for the originally scheduled maintenance mission planned for June 2000, NASA split the mission into two parts: Servicing Mission 3A and 3B.

Also known as STS-103, Servicing Mission 3A (SM3A) prioritized returning Hubble to a functional state and begin system upgrades. Major highlights include replacing the three Rate Sensor Units containing the telescope’s six gyroscopes as well as the installation of new computers, fine guidance sensors, and transmitters.

SM3A Crew Members:

Curtis Brown, Mission Commander

Scott Kelly, Pilot

Jean-François Clervoy, Mission Specialist

Michael Foale, Mission Specialist

John Grunsfeld, Mission Specialist

Steven Smith, Mission Specialist

Claude Nicollier, Mission Specialist

Learn more about SM3A at NASA's website: https://science.nasa.gov/mission/hubble/observatory/missions-to-hubble/servicing-mission-3a/