Casting a cold eye

Beryllium holds its shape in extreme temperatures "“ an ideal trait for a space mirror.
Date:1 January 2011 Tags:, ,

Predicting how a sensitive telescope will perform in the frigid environment of space can be a challenge.
By Alex Hutchinson

For example, in order to ensure the beryllium mirrors destined for the James Webb Space Telescope will function accurately, Northrop Grumman must cool them to minus 248 degrees Celsius – about 20 degrees cooler than operating temperature in orbit. The engineers then measure how the shape of every mirror changes and polish each to cancel out any warp, preventing deformations that could cloud the telescope’s results.

A total of 18 mirrors will undergo this treatment before engineers at Marshall Space Flight Centre in Huntsville, Alabama, integrate them to form a single 6,4 m reflective surface for the Webb, due to launch in 2014. The mirrors will direct faint infrared signals from distant planets, galaxies and stars, giving scientists an unparalleled perspective of the creation of the universe.

Related material
To read how the mirrors of the James Webb Space Telescopes were made. [click here]

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