The
Sunshield on NASA's James Webb Space Telescope is the largest part of
the observatory—five layers of thin membrane that must unfurl reliably
in space to precise tolerances. Last week, for the first time, engineers
stacked and unfurled a full-sized test unit of the Sunshield and it
worked perfectly. The Sunshield is about the length of a tennis court, and will be
folded up like an umbrella around the Webb telescope’s mirrors and
instruments during launch. Once it reaches its orbit, the Webb telescope
will receive a command from Earth to unfold, and separate the
Sunshield's five layers into their precisely stacked arrangement with
its kite-like shape. The Sunshield test unit was stacked and expanded at a cleanroom in the Northrop Grumman facility in Redondo Beach, California. The Sunshield separates the observatory into a warm sun-facing side
and a cold side where the sunshine is blocked from interfering with the
sensitive infrared instruments. The infrared instruments need to be kept
very cold (under 50 K or -370 degrees F) to operate. The Sunshield
protects these sensitive instruments with an effective sun protection
factor or SPF of 1,000,000 (suntan lotion generally has an SPF of 8-50). In addition to providing a cold environment, the Sunshield provides a
thermally stable environment. This stability is essential to
maintaining proper alignment of the primary mirror segments as the
telescope changes its orientation to the sun. The James Webb Space Telescope is the successor to NASA's Hubble
Space Telescope. It will be the most powerful space telescope ever
built. Webb is an international project led by NASA with its partners,
the European Space Agency and the Canadian Space Agency. For more information about the Webb telescope, visit: www.jwst.nasa.gov or www.nasa.gov/webb For more information on the Webb Sunshield, visit: http://jwst.nasa.gov/sunshield.html Photo Credit: NASA/Chris Gunn Rob Gutro
NASA's Goddard Space Flight Center
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