Servicing Mission 4
Originally targeted for Autumn 2008 it was postponed to early 2009 following the detection of an anomaly that affects the storage and transmittal of science data to Earth. The targeted launch date for STS-125 currently is 12 May 2009.
SM4 will feature the installation of two new cutting-edge science instruments which will enhance significantly Hubble's capabilities: the Cosmic Origins Spectrograph (COS) which will replace COSTAR, and the Wide Field Camera 3 (WFC3), which will replace WFPC2.
The mission will require 5 separate spacewalks each scheduled to last around 6.5 hours. The crew will also carry an IMAX camera to record the historic mission for a film to be released in 2010.
In addition to installing new instruments, an attempt will be made to repair the STIS instrument which is currently in safe mode. It is hoped to restore it to operational status by replacing parts of the instrument that ceased to function properly in August 2004.
Assignments for Servicing Mission 4
- Install WFC3 - Wide Field Camera 3
A high-resolution/wide-field camera with continuous wavelength coverage ranging from the ultraviolet to the near-infrared
- Install COS - Cosmic Origins Spectrograph
COS is the most sensitive ultraviolet spectrograph ever planned to fly on HST
- Repair STIS - Space Telescope Imaging Spectrograph
Restore STIS to operational status as it currently is in safe mode
- Repair ACS - Advanced Camera for Surveys
An attempt will also be made to fix ACS after its failure in January 2007
- Replace Rate Sensor Units (gyroscopes)
Complete change-out of all six gyroscopes, the heart of HST's pointing system, and HST's main wear-out items
- FGS - Fine Guidance Sensor
Last in a series of changed-out units that allow fine pointing of HST
- Replace Batteries
Replace the six batteries originally launched with Hubble in 1990, which are steadily losing capacity as they age
- Install Soft Capture and Rendezvous System
Install the Soft Capture and Rendezvous System on the bottom of Hubble to enable NASA to pursue options for the safe disposal of Hubble
- New Outer Blanket Layers (NOBLs)
Install the remaining three NOBLs to thermally protect equipment bays whose thermal insulation has been degraded by the space environment