ISS construction. Astronaut Rex J Walheim performing a space walk during the construction of the International Space Station (ISS). He is attached to the Canadarm2 robot arm (lower left) on the ISS. This was the first of four planned space walks (extravehicular activity, or EVA) on this mission. During the EVA, Walheim made power and data connections between the ISS and its new S0 (S-zero) Truss. Photographed on 11th April 2002, during Space Shuttle mission STS-110.