Wide Field Camera 3 (WFC3) will be the last main imaging camera to be installed. Everyone has seen the amazing pictures generated by the Wide Field Planetary Cameras (1 and 2). WFC3 will replace WFPC2 which was installed during the 1993 Servicing Mission and will be more than 10 years old by SM4. The new instrument will become Hubble's workhorse.

Since 1993, Charge Coupled Device (CCD) technology and optical coatings technology have progressed significantly. WFC3 will use the latest CCD technology and will maintain good imaging capabilities throughout the life of Hubble's mission. The WFC3 project represents an innovative approach to instrument management and development. Through reuse of key portions of WFPC1 and WFPC2 hardware, designs, and even personnel, WFC3 is being developed in a very cost-effective way.

COS

The Cosmic Origins Spectrograph (COS) will replace COSTAR, which is no longer necessary after the removal of FOC, the last instrument to use its services. COS is a medium resolution spectrograph specifically designed to observe into the near- and mid-ultraviolet. The ultraviolet region is particularly interesting for observing high energy activities such as those found in new hot stars and quasi-stellar objects (QSO's). It is also a good region for viewing the composition and character of the interstellar medium (ISM).

STIS

The Space Telescope Imaging Spectrograph (STIS) is a powerful general-purpose spectrograph that is complementary to - not superseded by - the Cosmic Origins Spectrograph. STIS was installed in Axial Science Instruments Bay 1 during Servicing Mission 2 on February 12, 1997. STIS performed on-orbit operations for apporoximately 65,000 hours (7 years. 171 days) before failing on August 3, 2004. The instrument remains in safe mode.

The attempted repair of STIS during this mission will restore Hubble's full spectroscopic capability by returning the STIS instrument to working order. This will be accopmplished by replacing a low voltage power supply board that contains the failed component.

The STIS repair will be performed with STIS remaining inside of Hubble. The astronauts will use existing EVA tools to gain access to the instrument. A new Main Electronics Box cover and Cooling System will fully restore STIS.