International Space Station repaired – sucessful space marathon finished

 

Yesterday NASA announced about finishing extraordinary space walk on ISS.

Nothing is perfect. It is truism, but refers also to high-end space technology which is ISS. Yesterday on 6th November 2015, at 1030 GMT Station commander Scott Kelly and flight engineer Kjell Lindgren began lasting almost eight hours extravehicular activity for repairing leaking cooling system. Cooling system had been disconnected by astronauts and then recharged with ammonia to fill missing amount of refrigerant. Astronauts were not able to finish covering spare radiator because ran out of time. Cooling system on ISS is one of most important systems. It is part of Active Thermal Control System (ATCS) responsible for keeping temperatures on ISS at desired level. Significant is cooling solar panels providing electricity for ISS. In case of damaging ATCS, panels without appropriate cooling will lose their efficiency. Overheating solar panels could eventually cause loss of power and as a consequence malfunctioning of other systems. ATCS is really unlucky. First malfunction took place in 2010, when pump broke and was changed for spare during spacewalk. Next breakdown was in 2013, when leakage was found in this same place. This time also spacewalk was necessary for servicing the ACTS and cooling pump controller box was changed. This year on 14th January, also potential ammonia leak was detected and was reason of evacuating of three crew members to Russian module (Russian module is equipped with independent external and internal cooling system). But further analysis showed that alarm was cause not by leakage but by sensor malfunction. After yesterday overtime spacewalk NASA and ISS crew are convinced that problem was solved permanently. No further spacewalks are planned for 2015; closest extravehicular activity is planned for 2016 for attaching new docking adapter (adapters if SpaceX will manage to rebuild their adapter destroyed during Falcon-9 1.1V fail flight on 28th June 2015) for Commercial Crew Transportation Capability for Commercial Crew Transportation Capability program vehicles.

Sources:
https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_Heavy_launches
https://en.wikipedia.org/wiki/International_Space_Station_maintenance#2013_.E2.80.93_Ammonia_Leak
https://en.wikipedia.org/wiki/External_Active_Thermal_Control_System
https://blogs.nasa.gov/spacestation/2015/11/06/pair-of-nasa-astronauts-wrap-up-second-spacewalk/