Development of a cryogenic test facility for Ariel’s primary mirror

Le résumé fourni par la source

The INAF Astronomical Observatory of Palermo has adapted the XACT facility to perform cryogenic testing of the 1-meter primary mirror for ESA’s Ariel mission, which operates at about 55 K. Thermoelastic effects at this temperature require a cryogenic interferometric campaign to recover the SFE and evaluate optical behavior in a representative environment. The facility includes a 2 m × 2 m vacuum chamber with a 1.4 m entrance hatch, a closed-loop helium cryocooler, and an optical setup based on a 4D interferometer, a hexapod, and a vacuum optical window. The mirror is supported by an isostatic multi-DoF fork mount, with cooling provided through copper plates, heat shields, and thermal straps linked by an aluminum structure. Simulations show thermal gradients below 5 K and mirror temperatures below the required 100 K. The paper presents the setup, test activities, first results, and related critical issues.

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