National Aeronautics and Space Administration

Legend:    INSTALL REMOVE
			Axial Bays
Year	Mission	Radial Bay	Inst. Pos. 1	Inst. Pos. 2	Inst. Pos. 3	Inst. Pos. 4
1990	HST Deployed 4-1990	WFPC 1 4-1990	GHRS 4-1990	FOS 4-1990	FOC 4-1990	HSP 4-1990
1991	NO CHANGE
1992	NO CHANGE
1993	First Servicing Mission 12-1993	Remove WFPC 1 12-1993	NO CHANGE	NO CHANGE	NO CHANGE	Remove HSP 12-1993
		Install WFPC 2 12-1993				Install COSTAR 12-1993
1994	NO CHANGE
1995	NO CHANGE
1996	NO CHANGE
1997	Servicing Mission 2 2-1997	NO CHANGE	Remove GHRS 2-1997	Remove FOS 2-1997	NO CHANGE	NO CHANGE
			Install STIS 2-1997	Install NICMOS 2-1997
1998	NO CHANGE
1999	Servicing Mission 3A 12-1999	NO CHANGE	NO CHANGE	NICMOS 1-1999 inoperable until NCS installed in 2002	NO CHANGE	NO CHANGE
2000	NO CHANGE
2001	NO CHANGE
2002	Servicing Mission 3B 3-2002	NO CHANGE	NO CHANGE	Install NCS 3-2002	Remove FOC 3-2002	NO CHANGE
				NICMOS turned on 3-2002	Install ACS 3-2002
2003	NO CHANGE
2004	NO CHANGE	NO CHANGE	STIS 8-2004 placed in safe mode	NO CHANGE	NO CHANGE	NO CHANGE
2005	NO CHANGE
2006	NO CHANGE
2007	NO CHANGE	NO CHANGE	NO CHANGE	NO CHANGE	ACS 1-2007 limited to 1 channel	NO CHANGE
2008	NO CHANGE	NO CHANGE	NO CHANGE	NCS/NICMOS 10-2008 inoperable until after SM4	NO CHANGE	NO CHANGE
2009	Servicing Mission 4 2009	Remove WFPC 2 2009	STIS Repair 2009	NO CHANGE	ACS Repair 2009	Remove COSTAR 2009
		Install WFC 3 2009				Install COS 2009

NOTE: In February 1999 the third servicing mission was split
into SM3A (December 1999) and SM3B (March 2002) following the failure of a third gyroscope.

1990 Initial complement at Deployment (STS-31):

• WFPC (1) - Wide Field/Planetary Camera - First-generation imaging camera. WFPC (1) operated in either Wide Field mode, capturing the largest images, or Planetary mode with higher resolution.

• GHRS - Goddard High Resolution Spectrograph - First-generation spectrograph. GHRS was used to obtain high resolution spectra of bright targets.

• FOS - Faint Object Spectrograph - First-generation spectrograph. FOS was used to obtain spectra of very faint or faraway sources. FOS also had a polarimeter for the study of the polarized light from these sources.

• FOC - Faint Object Camera - First-generation imaging camera. FOC was used to image very small fields of view and very faint targets.

• HSP - High Speed Photometer - First-generation photometer. This instrument was used to measure very fast brightness changes in diverse objects, such as pulsars. It was removed during the first servicing mission in 1993 to make way for COSTAR.

• FGS - Fine Guidance Sensors - Science/guidance instruments - The FGS's are used in a "dual-purpose" mode serving to lock on to "guide stars" which help the telescope obtain the exceedingly accurate pointing necessary for observation of astronomical targets. These instruments can also be used to obtain highly accurate measurements of stellar positions.

1993 Servicing Mission 1 (STS-61):

• WFPC2 - Wide Field Planetary Camera 2 - Second-generation imaging camera. WFPC 2 is an upgraded version of WFPC (1) which includes corrective optics and improved detectors.

• COSTAR - Corrective Optics Space Telescope Axial Replacement - Second-generation corrective optics. COSTAR is not an actual instrument. It consists of mirrors which refocus the abbreviated light from Hubble's optical system for first-generation instruments GHRS, FOC, and FOS. It replaces the first-generation photometer HSP.

1997 Servicing Mission 2 (STS-82):

• STIS - Space Telescope Imaging Spectrograph - Second-generation spectrograph/imager. STIS is used to obtain high resolution spectra. STIS has the special ability to simultaneously obtain spectra from many different points along a target. It replaced the first-generation spectrograph GHRS.

• NICMOS - Near Infrared Camera/Multi-Object Spectrometer - Second-generation imager/spectrograph. NICMOS is Hubble's only near-infrared (NIR) instrument. To be sensitive in the NIR, NICMOS must operate at a very low temperature, requiring sophisticated coolers. Problems with the solid nitrogen refrigerant have necessitated the installation of the NICMOS Cooler System (NCS) on SM3B to continue its operation. It replaces the first-generation spectrometer FOS.

2002 Servicing Mission 3B (STS-109):

• NCS - NICMOS Cooling System - Like COSTAR, NCS is not a separate instrument but rather a device which will allow NICMOS to continue operations by providing mechanical cooling for the NICMOS detectors. Results from the HOST mission indicate that the NCS will allow NICMOS to operate for up to 5 years beyond SM3B.
  CLICK HERE for a special look at the making of NCS.

• ACS - Advanced Camera for Surveys - The Advanced Camera for Surveys (ACS) is a third-generation imaging camera. This camera is optimized to perform surveys or broad imaging campaigns. It replaces the first-generation camera FOC.

2009 Servicing Mission 4 (STS-125):

• WFC 3 - Wide Field Camera 3 - Fourth-generation imaging camera. This camera will supplement ACS and guarantee imaging capability for Hubble after the Fourth Servicing Mission. It replaces the second-generation imaging camera WFPC 2.

• COS - Cosmic Origins Spectrograph - Fourth-generation spectrometer. COS is an ultraviolet spectrograph optimized for observing faint point sources with moderate spectral resolution. It replaces the second-generation corrective optics COSTAR which has not been used since the removal of the first-generation instruments GHRS, FOC and FOS.

• STIS Repair - The Space Telescope Imaging Spectrograph was installed in February 1997. STIS stopped functioning in August of 2004 due to a power supply failure. The instrument remains in safe mode. The attempted in-place repair of STIS during this mission will restore Hubble's spectroscopic capability.

• ACS Repair - The Advanced Camera for Surveys was installed in March 2002. ACS suffered a power supply failure in January 2007, leaving two of its three cameras/channels dark. ACS in-place repair will restore all three cameras to functional capacity and allow for the ability to do deep parallel observations with other Hubble instruments.