Amazing Space logoServicing Mission 4 > SM4 Glossary

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Servicing Missions

Hubble was the first space telescope designed to be serviced in space. Scientists believed that periodic servicing missions would extend Hubble’s operating life and keep the observatory up-to-date. Astronauts have already visited Hubble four times. The first servicing mission was in December 1993 and the second in February 1997. The third mission was split into two visits. Part A took place in December 1999 and part B in March 2002. Another visit is scheduled for May 2009.

Soft Capture Mechanism

When Hubble reaches the end of its mission, NASA must be able to safely return the telescope to Earth. When that time comes, the Space Shuttle will no longer be operating, so another means of capturing the telescope must be available. The soft capture mechanism is a compact device that, when attached to the Hubble Space Telescope, will assist in its safe de-orbit. This device has structures and targets that will allow a next generation space vehicle to more easily capture and guide the telescope into a safe, controlled re-entry.

Solar Arrays

Two rigid, wing-like arrays of solar panels that convert sunlight directly into electricity to operate the Hubble Space Telescope’s scientific instruments, computers, and radio transmitters. The solar arrays are designed for replacement by visiting astronauts during servicing missions. They were most recently replaced during SM3B.

Space Telescope Imaging Spectrograph (STIS)

The Space Telescope Imaging Spectrograph (STIS) is a general-purpose spectrograph that spans ultraviolet, visible, and near-infrared wavelengths. It was installed in February 1997 during the Second Servicing Mission. A spectrograph works by breaking up light from an object into its individual wavelengths so that its composition, temperature, motion, and other chemical and physical properties can be analyzed.

Ultraviolet (UV) Light

The part of the electromagnetic spectrum that has slightly higher energy than visible light, but is not visible to the human eye. Just as there are high-pitched sounds that cannot be heard, there is high-energy light that cannot be seen. Too much exposure to ultraviolet light causes sunburns.