May 12 (UPI) -- A pair of NASA astronauts, Expedition 51 Commander Peggy Whitson and Flight Engineer Jack Fischer, have completed the 200th spacewalk in support of the International Space Station.
During their time outside the station, Whitson and Fischer replaced an avionics box situated on the station's starboard 3 truss. The box supplies electricity to a variety of science experiments.
The spacewalk officially began at 9:08 a.m. EDT. Whitson spent 4 hours and 15 minutes outside the space station, while Fischer spent 4 hours and 13 minutes in space.
The pair of astronauts were originally scheduled to replace a selection of replacement hardware and spare parts stored outside the station but a water leak in a component of one of the two space suits forced a delay. As a result, NASA officials decided to limit the time spent outside the station to roughly four hours -- only enough time to accomplish the primary objective.
Friday's mission was Whitson's ninth spacewalk. She already held the record for most spacewalks executed by a female astronaut. The historic spacewalk was Fischer's first.