Video: Highlights of second Expedition 50 spacewalk

SpaceX’s Dragon supply ship, loaded with nearly 5,500 pounds of cargo and experiments, aborted an approach to the International Space Station on Wednesday after encountering a problem in its GPS navigation system.

Space station commander Peggy Whitson and astronaut Jack Fischer are set for a two-and-a-half hour spacewalk Tuesday, a quickly-planned excursion to replace a recently installed external computer that failed Saturday.

Two space station astronauts are gearing up for a planned six-and-a-half-hour spacewalk Friday to replace a presumably shorted out solar array voltage regulator that knocked one of the lab’s eight power channels out of action late last year.