The core is a very critical region
<p>of the James Webb Space Telescope, because it is where the hot spacecraft (always sun-facing) connects to the cold optical telescope (never
sun-facing) via a “deployable tower assembly” (DTA) and electrical harnessing, both of which pass through an opening in the center of the sunshield and connect the two major elements—spacecraft and telescope. An additional major part of the core region is the ISIM (Integrated Science Instrument Module) electronics compartment (IEC), an enclosure located on the cold telescope side, but containing electronics that run warm—at essentially spacecraft temperatures. IEC’s proximity to ISIM—it’s located directly below
ISIM—is a non-trivial thermal control challenge. 
</p><p>The Project recently carried out an important thermal
vacuum campaign, “Core2,” in NASA Goddard’s Space Environment Simulator (SES) chamber. The “2” obviously indicates this was a second such test (the first was done quite a few years ago, in 2009), and it was executed with much greater detail and fidelity to the core hardware that will actually fly in space.
</p><p>Simply put, Core2 was a highly targeted, thermal only,
cryogenic vacuum test—there were no optics.
</p><p>Read more about this test in the Summer 2016 news letter: jwst.nasa.gov/resources/WebbUpdateSummer2016.pdf
</p><p>Here the Core2 test article being
removed from NASA/Goddard’s Space Environment Simulator (SES) following testing. When installed in the chamber, there
were only 8 inches of vertical clearance with the chamber roof.
</p><p>Image credit: NASA/Desiree Stover
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NASA's James Webb Space Telescope
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