Commander Peggy Whitson and Flight Engineer Jack Fischer, both NASA astronauts, conducted the 200th spacewalk in support of the International Space Station’s assembly and maintenance since 1998.

Among the work, the duo replaced an avionics box responsible for routing power and data commands to experiments on the orbital outpost. It was the ninth spacewalk for Whitson, who is now in third place on the all-time list for most spacewalking hours, and Fischer’s first.