The two U.S. astronauts installed two new high-definition TV cameras and a camera light, tightened bolts on a solar-panel rotary joint, tied down the brake handles for a rail car, and whipped through a few other chores.
Mission Control, meanwhile, kept news about a devastating launch pad explosion at Cape Canaveral from the two spacewalkers while they were outside.
SpaceX was fueling its unmanned Falcon rocket for a test engine firing when a fireball erupted, an hour into the spacewalk.
SpaceX is one of two companies supplying the space station for NASA.
The newly installed docking port is meant for the SpaceX crew Dragon, as well as Boeing's Starliner capsule, also still in development.
