Servicing Mission 3B will focus on the installation of the Advanced Camera for Surveys and more efficient, rigid solar arrays. Astronauts also will install the aft shroud cooling system, which will allow the science instruments to operate simultaneously at lower temperatures. In addition, an advanced cooling system will be installed on the Near Infrared Camera and Multi-Object Spectrometer, which became dormant after its solid nitrogen coolant was exhausted in January 1999. The application of new external thermal coverings will be completed.

Servicing Mission 4 will see the addition of two new science instruments, the Cosmic Origins Spectrograph and the Wide Field Camera 3. A refurbished Fine Guidance Sensor also will be installed, completing the refurbishment of all Fine Guidance Sensors on Hubble.

Hubble is scheduled to be decommissioned in 2010.