JWST Observatory
The term JWST Observatory refers to the space-based portion of the JWST system and is comprised of three elements: the Integrated Science Instrument Module
(ISIM), the Optical Telescope Element (OTE), and the Spacecraft Element (Spacecraft Bus and
Sunshield).
Here are two labeled artist's conceptions of the spacecraft.
Click on each one for a larger version.
The Integrated Instrument Module (ISIM) includes the following science instruments:
The OTE is the eye of the JWST Observatory. The OTE
gathers the light coming from space and provides it to the science instruments
located in the ISIM.
The sunshield subsystem separates the observatory
into a warm sun-facing side (spacecraft bus) and a cold anti-sun side (OTE and
ISIM). The sunshield keeps the heat of the Sun, Earth, and spacecraft bus electronics
away from the OTE and ISIM so that these pieces of the Observatory can be kept
very cold (The operating temperature has to be kept under 50 K or -370 deg F).
The spacecraft bus provides the support functions for the operation of the JWST Observatory. The bus houses the six major subsystems needed to operate the spacecraft: the Electrical Power Subsystem, the Attitude Control Subsystem, the Communication Subsystem, the Command and Data Handling Subsystem, the Propulsion Subsystem, and the Thermal Control Subsystem.