What appears to be a golden cage being lowered over a complex piece of technology is actually equipment that will simulate an environment in space to ensure the science instruments of the James Webb Space Telescope can withstand the harsh conditions.

The golden cage is actually the Surrogate Thermal Management System (STMS), and it provides a simulation of the thermal environment expected during the mission. In the photo, the STMS frame is being lowered over Integrated Science Instrument Module (ISIM) in preparation for a cryogenic test. The STMS will maintain the temperature balance as the ISIM is cooled to 40 kelvin (-233.1 C / -387.7 F) inside a vacuum chamber at the Goddard Space Flight Center in Greenbelt, Maryland.

The ISIM is one of three major elements that comprise the Webb Observatory flight system. The ISIM is the heart of the James Webb Space Telescope, what engineers call the main payload. This is the unit that will house the four main instruments that will detect light from distant stars and galaxies, and planets orbiting other stars.

The cryogenic test will run until the fall of 2014.

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.