JWST payload module (ISIM)
JWST Integrated Science Instrument Module (ISIM), mounted on the System Integration Fixture (SIF – yellowish structure) that will support it during cryogenic testing. On top of ISIM, the flat structures are the harness radiators that will dissipate the heat from the cabling into space and make sure that the heat produced by the warm electronics in the ISIM Electronics Compartment (IEC) is not transferred to the very cold instruments via the thermally conductive cable harnesses. The IEC compartment can be seen on the back, wrapped in protective Multi Layer Insulation (MLI). The IEC houses all the control electronics for the instruments.