HST SM4 RSU / Gyroscope Replacement EVA

  • Released Friday, August 22, 2008
  • Updated Friday, August 9, 2019 at 4:24PM
  • ID: 10234
Hubble was designed to use three of six onboard gyroscopes to meet its very precise pointing requirements, with the other three held as spares. Gyros have limited lifetimes, and three of the six (all installed in late-1999) are currently working. Following a thorough analysis and testing by engineers, it was determined that Hubble could operate productively on two gyros. After the implementation of three new control modes in Hubble's main computer, and major changes to Hubble's planning and scheduling system at the Space Telescope Science Institute, two-gyro operations began in 2005. By operating on two gyros, with the other gyro turned off (until needed), it is expected that Hubble can continue science operations through the end of 2008. With SM4 scheduled for mid-2008, a fresh set of six new gyros is needed to make the most of Hubble's new science instruments and lifetime peak performance through 2013. Each Rate Sensing Unit (RSU) contains two gyroscopes. Astronauts will replace all three RSUs giving Hubble a full compliment of six new gyroscopes.

HST SM4 RSU / Gyroscope Replacement EVA completed and edited animation sequence.

Animated sequence depicts the replacement of three Rate Sensing Units (RSU) containing gyroscopes during Hubble Space Telescope Servicing Mission 4.

Animated sequence depicts the replacement of three Rate Sensing Units (RSU) containing gyroscopes during Hubble Space Telescope Servicing Mission 4.

Animated sequence depicts the replacement of three Rate Sensing Units (RSU) containing gyroscopes during Hubble Space Telescope Servicing Mission 4.

Animated sequence depicts the replacement of three Rate Sensing Units (RSU) containing gyroscopes during Hubble Space Telescope Servicing Mission 4.

Credits

Please give credit for this item to:
Goddard Space Flight Center

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Datasets used in this visualization

HST (Collected with the WFPC2 sensor)

Wide-Field Planetary Camera 2 (WFPC2) was installed in Dec 1993 and used to obtain high resolution images of astronomical objects. This camera was removed in the last servicing mission so it is no longer in service.

Dataset can be found at: http://www.stsci.edu/hst/wfpc2/wfpc2_diag.html

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