M1M3 Cell and Support System

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M1M3 on Telescope

Location of the M1M3 Cell and Mirror on the Telescope

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Mirror supported on Cell• Mirror Wt: ~17000 kg• Total Wt (Mirror + Cell + Internals): ~53000 kg• Key systems:

Gravity support and figure control force actuators Hardpoint Struts to locate mirror Thermal control via cooling air injection into mirror cores

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Pneumatic Support Actuators• React gravity force and• Provide figure correction force• 112 Dual axis actuators• 44 Single axis actuators• Force Range: 2500 N axial, 2000 N lateral• Non-repeatable error: +/- 0.5N RMS max• Do not locate mirror

Piston Style pneumatic cylinders

Pressure servo valves

Loadspreader bonded to mirror back face

Inner Loop Controller monitors load cell signal and adjust servo valves

Load Cells measure force produces

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Mirror Hardpoint Struts• Locate mirror with respect to Cell• Hexapod configuration – provides kinematic

adjustment in all 6 DOF• Mechanical breakaway mechanism to

prevent excessive force on mirror• Stiffness: 100+ N/mm • Control system adjusts support actuators to

maintain zero force through hardpoints.

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Mirror Thermal Control Units• 97 units pull air through liquid cooled heat

exchangers and pressurize cell interior.• Nozzle direct cooling air from cell into each

mirror core through vent holes in the back face.

• Ejected air from each core is pulled back through the thermal control units completing the cycle.

• Temperature uniformity is augmented by trimming resistor heaters in each unit.