<p>Testing is crucial part of NASA's success on Earth and in space. So, as the actual flight components of NASA's James Webb Space Telescope come together, engineers are testing the non-flight equipment to ensure that tests on the real Webb telescope later goes safely and according to plan. Recently, the "pathfinder telescope," or just “Pathfinder,” completed its first super-cold optical test that resulted in many first-of-a-kind demonstrations.
</p><p>"This test is the first dry-run of the equipment and procedures we will use to conduct an end-to-end optical test of the flight telescope and instruments," said Mark Clampin, Webb telescope Observatory Project Scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It provides confidence that once the flight telescope is ready, we are fully prepared for a successful test of the flight hardware."
</p><p>The Pathfinder is a non-flight replica of the Webb telescope’s center section backplane, or “backbone,” that includes mirrors.
</p><p>The flight backplane comes in three segments, a center section and two wing-like parts, all of which will support large hexagonal mirrors on the Webb telescope. The pathfinder only consists of the center part of the backplane. However, during the test, it held two full size spare primary mirror segments and a full size spare secondary mirror to demonstrate the ability to optically test and align the telescope at the planned operating temperatures of -400 degrees Fahrenheit (-240 Celsius).  Read more: <a rel="nofollow" class="external text" href="http://www.nasa.gov/feature/goddard/nasas-webb-pathfinder-telescope-successfully-completes-first-super-cold-optical-test">www.nasa.gov/feature/goddard/nasas-webb-pathfinder-telesc...</a>
</p><p>Credit: NASA/Goddard/Chris Gunn
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<bdi><a href="https://www.wikidata.org/wiki/Q110278636" class="extiw" title="d:Q110278636"><span title="American photographer">Chris Gunn</span></a>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/gsfc/21604092023/">NASA's Webb "Pathfinder Telescope" Successfully Completes First Super-Cold Optical Test</a>