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Technicians successfully test James Webb Space Telescope’s Deployable Tower Assembly. 

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This tower creates a 4-foot (1.2 meter) gap between Webb’s mirror and science segment and it’s sunshield and spacecraft bus segment.

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This gap allows Webb’s active and passive cooling systems to cool its mirrors and sensors down to super cold temperatures.  

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Mirrors and instruments need to be super cold for Webb to perform its science.

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A special pulley and counterbalance system perfectly offset the weight of Webb’s mirrors and instrument segment

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Canceling the effects of Earth’s gravity for this test.  The tower slowly extended upward over the course of several hours. 

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This is the same maneuver it will perform once in space.  NASA’s James Webb Space Telescope will be the world’s premier space science observatory when it launches.  

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Webb is an international program led by NASA with its partners, the European Space Agency and the Canadian Space Agency.

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