Layer 1 is closest to the Sun and is bigger and flatter.[6] The first layer blocks 90% of the heat, and each successive layer blocks more heat, which is reflected out the sides.[6][17] The sunshield allows the optics to stay in shadow for pitch angles of +5° to −45° and roll angles of +5° to −5°.[3] The layers are designed with Thermal Spot Bond (TSB), with a grid pattern bonded to each layer at intervals.[6] This helps stop a rip or hole from increasing in size should one occur.[6]