Space shuttle Atlantis repairs solar-powered Hubble Telescope

May 12, 6:16 PMPhoenix Green Business ExaminerBrian Coppa

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Space shuttle Atlantis launch (wikimedia.org).

Atlantis’ crew completed a planned survey of the shuttle heat shielding today, and confirmed a few damaged areas in tiles occurring during Monday’s launch that experts will review closely in the coming days. Flight Director Tony Ceccacci stated that upon an initial observation, damage found during the inspection appeared to be minor and not a major source of concern for NASA. The Atlantis damage was composed of small dents in the thermal tiles along an area of approximately 21 inches located on the starboard side of the spacecraft, where the wing meets the forward fuselage. For every shuttle mission since the Columbia disaster in 2003, there has been a contingency plan in place to have a rescue shuttle in place if needed, as in the case of Endeavor which is available during this risky Hubble Space Telescope maintenance mission.

This mission will return the Atlantis space shuttle to the Hubble Space Telescope for one last visit before the shuttle fleet is discontinued in 2010. Over 11 days and five spacewalks, the shuttle Atlantis’ crew will perform critical maintenance and upgrades to the telescope, allowing it to function at least another five years.

In 1990, the shuttle Discovery launched Hubble and released it into an orbit 304 nautical miles above the Earth. Over this period, it has circled Earth more than 97,000 times and provided more than 4,000 astronomers access to the stars not visible from inside Earth’s atmosphere. Hubble has revealed the mysteries surrounding some of science’s key questions on the origins of the Universe and provided numerous breath-taking views of the heavens.

Hubble has needed electricity to operate in space the last 19 years, as is the case for all satellites. Flanking the telescope's tube are two thin, blue solar arrays. The solar arrays convert sunlight directly into electricity to run the telescope's scientific instruments, computers, and radio transmitters. Some of the energy generated is stored in on-board batteries enabling the telescope to function while located in Earth's shadow with respect to the Sun (which is about 36 minutes out of each 97-minute orbit). Each battery contains enough energy when fully charged to sustain the telescope in normal science operations mode for 7.5 hours, which is equivalent to five orbits.

Hubble telescope in orbit (static.howstuffworks.com).

The high efficiency solar panels have supporting frames composed of aluminum-lithium, which is stronger and lighter than the type of aluminum typically implemented in spacecraft components. These supports are much less sensitive to the extreme temperature fluctuations of Hubble’s harsh environment. During each 97-minute orbit, Hubble spends about two-thirds of its time in intense sunlight and the other third in the frigid darkness of Earth’s shadow. These ever-changing conditions lead to temperature changes from -94 degrees Fahrenheit (-70 degrees Celsius) and 187 degrees Fahrenheit (86 degrees Celsius) over the course of an orbit, which would lead to structural defects more readily in less appropriate materials.

The solar arrays will be inspected for replacement by Atlantis astronauts and will be folded in to be free of obstruction for interaction with this shuttle.

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For more info: See www.nasa.gov for Atlantis mission updates.