Assertion: telescope's optic | /r/HasProperty | active
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Source sentences:
text: Each telescope has an alt-azimuth mount with total mass around 350 tonnes, and uses active optics with 150 supports on the back of the primary mirror to control the shape of the thin (177mm thick) mirror by computers.
text: This is unlike terrestrial telescopes like the Keck which continually adjust their mirror segments using active optics to overcome the effects of gravitational and wind loading, though the Webb telescope will use 126 small motors, and is made possible because of the lack of environmental disturbances of a telescope in space.