Spacewalking astronauts prep space station for new parking spot

Spacewalking astronauts prepped the International Space Station on Friday for a new parking spot reserved for commercial crew capsules.

The 402-kilometre-high complex already has one docking port in place for the SpaceX Crew Dragon and Boeing Starliner, which should start carrying up astronauts as early as next year. Friday's spacewalk set the stage for a second docking location.

NASA astronaut Shane Kimbrough disconnected all four cables from an old docking port, using some extra force on one. He looped a spare tether around the balky cable and pulled, and off it came.

"Nicely done, Shane," Mission Control radioed.

On Sunday, flight controllers in Houston, Texas, will move the old port to a location that will provide better clearance for the future ships. Then next Thursday, the crew will conduct another spacewalk to secure the unit.

A new docking device similar to one installed last summer will fly up late this year or early next, and hook onto this port.

Morespacewalksplanned before April 10

As Kimbrough worked on the docking port and replaced a computer-relay box, Pesquet hunted for signs of an ammonia coolant leak in outdoor plumbing. The leak, while still small, has worsened recently, and NASA wants to pinpoint the location.

• Astronauts perform spacewalk to replace space station batteries

Pesquet patted and tugged at hoses, but did not spot any frozen flakes of ammonia. A GoPro camera caught his every move for playback later.

"No leaks. No flakes whatsoever," he reported.

Also on the spacewalkers' to-do list Friday: replace a pair of Japanese cameras and grease latching mechanisms on the end of the big robot arm.

NASA wants to cram in two and possibly three spacewalks before Kimbrough, the station's commander, returns to Earth on April 10.

Before a third spacewalk can be conducted, Orbital ATK needs to launch a cargo ship to the space station with replacement parts. That shipment was supposed to be there by now, but repeatedly has been delayed because of rocket concerns. It's unclear when the Atlas V rocket will be ready to soar from Cape Canaveral, Fla.

NASA has been contracting out cargo deliveries since the end of the space shuttle program in 2011. The space agency is counting on private companies to do the same with astronauts.