Reuters/Cape Canaveral, Florida
Two US astronauts floated outside the International Space Station on Friday on a four-hour spacewalk with an abbreviated task list after a cable supplying power, oxygen, cooling water and communications to a spacesuit developed a leak, Nasa said.
Station commander Peggy Whitson, a veteran with eight previous spacewalks, and flight engineer Jack Fischer, who was making his first outing, left the station's airlock around 9:15am EDT.
The start of the spacewalk, originally slated to last 6.5 hours, was delayed more than an hour while the US National Aeronautics and Space Administration revamped plans due to the leak, which developed as Fischer’s suit was being prepared.
"Lot of curveballs this morning," Nasa astronaut Kjell Lindgren radioed to the crew from Mission Control in Houston.
The spacewalk is the 200th in support of station assembly and maintenance since construction began in 1998 on the $100bn laboratory that flies about 250 miles (400 km) above Earth.
Whitson and Fischer shared a second good cable, known as an umbilical, as they prepared to leave the station's airlock, which burned through some of their spacesuits' battery power.
As a result, Nasa decided to trim the spacewalk down to four hours, which left time for just one task, said mission commentator Rob Navias.
Whitson and Fischer will replace a faulty 200-pound electronics box that routes commands and data to experiments.
Other work that will be rescheduled for a future spacewalk includes installing equipment to troubleshoot a cooling system problem with the station's $2bn dark matter detector and attaching a debris shield onto an exposed docking port that is being prepared for commercial space taxis under development by Space Exploration Technologies, or SpaceX, and Boeing Co.