On May 12, 2017, American astronauts Peggy Whitson and Jack Fisher performed the spacewalk for several repair and maintenance tasks. Their first job was to remove and replace an ExPRESS Carrier Avionics box located on the starboard-side S3 truss of the space station. After that Fischer repaired the Japanese robotic arm’s thermal insulation, while Whitson installed a terminator cap on the AMS instrument, a massive experiment attached to the station truss designed to study dark matter and antimatter. The spacewalk lasted 4 hours and 13 minutes. This was the ninth spacewalk for Peggy Whitson and the first for Jack Fisher. This EVA was the 200th spacewalk in support of the International Space Station assembly and maintenance since December 1998, and the fifth this year.