A pair of NASA astronauts on board the International Space Station or ISS, Expedition 45 Commander Scott Kelly with U.S. Astronaut Kjell Lindgren went overtime on their Nov. 6 spacewalk but completed the task of restoring the port truss ammonia cooling system to its original configuration.
It was the pair's second spacewalk, following their first on Oct, 28. Both were able to return ammonia to the desired levels in both back-up and prime systems, reported NASA.
The ISS spacewalk duration was seven hours and 48 minutes, and there was a minor drift from the planned tasks, and they had no time to cover a spare radiator called Trailing Thermal Control which Lindgren retracted earlier. The radiator was fully redeployed and put in a dormant state. It was deployed during the November 2012 spacewalk by Sunita Williams and Aki Hoshide when they tried to separate a leak in the cooling supply of the truss.
Williams and Hoshide replumbed the system to the backdoor radiator but the leak persisted and a different component was found the main culprit during the May 2013 spacewalk.
The Telegraph said, highly-toxic ammonia is used to cool electronics at the space stations and there have been problems in the thermal system. Kelly and Lindgren started the ISS spacewalk at 11:22 a.m, Friday, for a 6.5-hour spacewalk, to complete the repair to a system which malfunctioned three years back.
According to NASA Knows, a spacewalk or extravehicular activity (EVA) is when an astronaut exits from his vehicle while in space. It is done so astronauts work outside their spacecraft to test new equipments as well as do experiments or maintenance or repair works, instead of bringing their vehicles back to Earth for repair.
Astronauts wear spacesuits to be safe. It has oxygen and water they need to breathe and drink. They put the pressurized spacesuits hours before the spacewalk. Once on their suits, they breath pure oxygen for a few hours to get rid of the nitrogen on their bodies, lest they will have gas bubbles that will cause pain in the wrists, elbows, shoulders and knees.
Astronauts exit the aircraft through the airlock which has two doors. The airlock is airtight to keep the air from going out. Astronauts go through the airlock's first door and lock it, so when they open the second door, no air can get out of the spacecraft still. After the spacewalk, they get inside the spacecraft via the airlock.
Astronauts stay safe during spacewalks by using safety rope-like tethers to stay close to their vehicles and to keep them and their tools from floating away into space. Another way to keep them safe is by wearing Simplified Aid for EVA Rescue or SAFER, which is worn like a backpack. It uses small thrusters so they can move around in space.
When they go unthetered and float away, they can fly back to the spacecraft with it. SAFER is controlled with a small joystick, just like the one used in a video game.
