ESA Science & Technology - Thermal and vacuum test rig for JWST's Integrated Science Instrument Module

This image shows part of the thermal and vacuum test rig for the James Webb Space Telescope's (JWST) Integrated Science Instrument Module (ISIM). It is taken from inside a large thermal and vacuum chamber, called the Space Environment Simulator, at NASA's Goddard Space Flight Center (GSFC). The bottom of the picture shows the lower part of the test rig. This lower part consists of the optical telescope simulator (OSIM) and its mounting system.

The OSIM mimics the JWST telescope and provides optically representative test beams to the science instruments during the various performance and calibration tests. The OSIM itself will not fly in space, however, it is an important part of the testing programme to verify that the Webb telescope’s science cameras and spectrographs will function as planned.

During the tests the ISIM reached a temperature of -233 ºC – the same temperature it will experience in space. The gold foil material is MLI (Multi Layer Insulator), used to thermally isolate the warm parts from the colder subsystems and to prevent the introduction of spurious thermal background light.

ISIM is not visible, as it sits on top of the ceiling shown in this image.