jsc2021e037879 (8/24/2021) --- A preflight view of the Touching Surfaces investigation hardware. The Touch Array (136 mm x 45 mm x 8 mm). Housing : Aluminum (EN-AW 7075 T7351). (Panel A) Nine metallic test surfaces: 3 x steel, copper, brass (from left to right) – with no greater than 3 ?m and less than 3 ?m laser structure (from top to bottom); (Panel B) in each Touch Array two 3 printed humidity detectors are mounted. Image Courtesy DLR