US astronauts complete fix work on ISS cooling system

Floating in the Quest airlock compartment, the astronauts plan to switch their spacesuits to battery power around 7:10 a.m. EST (GMT-5) Friday to officially kick off NASA EVA-33.

Through a spacewalk conducted in November 2012, astronauts tried to isolate a suspected ammonia leak in the cooling system by re-plumbing the system to a backup radiator. A different method was subsequently adopted for fixing the ammonia leak; the failed pump was replaced with a new one.

“Now leak-free, officials made a decision to restore the port truss cooling system to its primary method of dispelling heat”, NASA said in a statement.

Americans Scott Kelly, who is the current station commander, and flight engineer Kjell Lindgren took their second spacewalk in the last nine days.

But with the space agency’s schedules pegging a journey to the Red Planet in the mid-2030s timeframe, it may fall to even more future recruits to become the first astronauts to walk on Mars.

Fridays mission was aimed at more permanently repairing part of the ammonia cooling system that was fixed in 2012. After sufficient time had passed for the contamination level to drop off, the astronauts were allowed to return to the work site.

Japanese astronaut Kimiya Yui will coordinate the spacewalk from inside.

There was one minor glitch on the long spacewalk to reconfigure the cooling system.

Early in Friday’s outing, the spacewalkers reported seeing flakes of ammonia when disconnecting a few of the equipment, but the crew was never in any danger, said NASA commentator Rob Navias.

This time, the spacewalkers will have to deal with a highly toxic substance outside the global Space Station. That meant topping off the ammonia coolant supply and retracting a backup radiator, accordion style; both tasks went well. “I’ll be back w you again soon!”

Their shorter spacewalk on October 28 featured a robot-arm lube job and other mundane maintenance.