During the next servicing mission, Servicing Mission 4 (SM4), astronauts will make the final trip to the Hubble Telescope. Over the course of five spacewalks, they will install two new instruments, repair two inactive ones, and perform the component replacements that will keep the telescope functioning at least into 2014. The effort-intensive, rigorously researched, exhaustively tested mission also involves diverse groups of people on the ground throughout the country.

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Hubble Space Telescope Servicing Mission 4

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Servicing Mission 4 (SM4) is the final Shuttle mission for the Hubble Space Telescope. Astronauts will bring new instruments to Hubble along with gyros, batteries and other components crucial for the telescopes continued success through the year 2013.
Mission Manifest
With more than 17 years of historic and trailblazing science already accomplished, Hubble will be reborn with SM4. The mission will feature the installation of two new cutting-edge science instruments to enhance Hubbles capabilities by large factors, the refurbishment of Hubbles subsystems and extension of operating life to at least 2013. Astronauts will also attempt the first ever on-orbit repair of two existing instruments the Space Telescope Imaging Spectrograph and the Advanced Cameras for Surveys.

SM4 was originally planned for 2004, but was postponed after the Columbia Space Shuttle tragedy in 2003 and then canceled in light of Agency safety concerns. Following the successful recovery of the Shuttle program and a re-examination of SM4 risks, NASA approved one last servicing mission. The reinstated SM4 is currently scheduled for flight in Fall 2008.
The new instruments are the Cosmic Origins Spectrograph and Wide Field Camera 3. A refurbished Fine Guidance Sensor will replace one degrading unit of three now onboard, and will maintain a robust ability to point the telescope. Astronauts will also install gyros, batteries and thermal blankets to ensure Hubble functions efficiently for a minimum of five years after servicing.
Repairs and a Future Rendezvous
Space Telescope Imaging Spectrograph — STIS, the most versatile spectrograph ever to fly on Hubble, ceased operations in August 2004 due to failure of its power supply. In order to restore STIS to operational status, astronauts may attempt an on-orbit replacement of a failed electronics board inside one of its main electronics boxes. COS and STIS are highly complementary and would work effectively together to provide a full set of spectroscopic tools for astrophysical research.
Advanced Camera for Surveys — ACS has produced many of the most popular and dramatic images from the Hubble Space Telescope over the last few years, but in January 2007 the instrument had a serious power failure which caused the three observing channels, the Wide Field Channel, The Solar Blind Channel and the High Resolution channel, to cease operation. The Solar Blind Channel was returned to service in February 2007. Astronauts will attempt to repair the Advanced Camera for Surveys by replacing the CCD electronics box in the Wide Field Channel and power this box with a replacement low voltage power supply. If this repair is successful, ACS will again provide the most sensitive images available at visible and near-infrared wavelengths.
Soft Capture Mechanism — The SCM is a compact device that, when attached to the Hubble aft bulkhead, will enable and assist in the safe de-orbit of the Hubble Space Telescope at the end of its useful life. This circular mechanism has structures and targets that will allow a next-generation vehicle to more easily capture and guide the telescope into a safe controlled re-entry.
www.nasa.gov/hubble

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