Gaia QM deployable sunshield set-up in the LSS
On 11 July the qualification model (QM) of Gaia's deployable sunshield was installed inside the Large Space Simulator (LSS) at ESTEC. Over the next days the set-up was finalized for the upcoming thermal vacuum/thermal balance (TV/TB) test, which is performed inside the LSS under simulated space conditions.
This overhead view of the test set-up in the LSS main vacuum chamber shows the QM sunshield in deployed configuration during the test preparations.
For the TV/TB test a large reflective foil is installed in front of the opening where the beam of the Sun simulator enters the chamber, forming a mask. A window in the middle of the mask matches exactly the shape of the deployed sunshield. The mask allows light to impinge directly only onto the Sun side of the sunshield and blocks light that would otherwise pass the sunshield and reflect inside the vacuum chamber back onto the shadow side of the sunshield.
This picture was taken during the test preparations, when the light tightness of the mask was verified before the start of the actual TV/TB test. The blue circle on the mask is from the Sun simulator light beam entering through the round opening in the chamber behind the mask.
Also visible are the three masts of the zero-g kit (used to simulate weightlessness) that stand next to the assembly, with the three panels of the QM sunshield each attached to a pulley and counterweight system on the masts.
The LSS chamber was closed on 20 July for the start of the TV/TB test.