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Observatory: The Optical Telescope Element (OTE)

The Optical Telescope Element (OTE) is the eye of the James Webb Space Telescope Observatory. The OTE gathers the light coming from space and provides it to the science instruments.

OTE diagram

The OTE consists of the mirrors as well as structures and subsystems that support the optics.

The OTE is made up of:

1) 6.5 meter diameter primary mirror made of 18 hexagonal segments

2) Round 0.74 meter Secondary mirror

3) Tertiary mirror and Fine Steering Mirror, both of which are contained in the Aft Optics Subsystem.

4) Telescope structure (which includes the primary mirror backplane assembly, the main backplane support fixture (BSF), the secondary mirror support structure, and the deployable tower array) The BSF will house the instrument module.

5) Thermal Management Subsystem

7) Aft Deployable ISIM Radiator (ADIR)

9) Wavefront sensing and control

The completed primary mirror on the flight telescope structure. The black covers on the gold-coated mirror segments are temporary to keep the mirror surfaces protected:

NASA's James Webb Space Telescope Primary Mirror Fully Assembled
Credit: NASA/Chris Gunn