Gaia primary mirror
One of the Gaia primary (M1) mirrors, pictured at the premises of Sagem, France.
Each M1 mirror has dimensions of 1.49 × 0.54 m, and weighs about 40 kg. They are constructed from sintered silicon carbide (SiC), which results in a lightweight, strong and rigid mirror.
The mirror blanks were made by Boostec, France, and then coated with a thin layer of silicon carbide (by chemical vapour deposition) by Schunk Kohlenstofftechnik, Germany. Polishing is performed by Sagem, France.