There were three EVA (Extra Vehicular Activity) sessions conducted by pairs of spacewalking astronauts and cosmonauts during the Christmas period. The first was made on 21 December after NASA deemed that the previously discovered coolant loop fault would need spacewalks to fix.
US Astronauts Rick Mastracchio and Mike Hopkins conducted this EVA to remove the faulty coolant pump unit that suffered a valve problem earlier in December. The astronauts exited the Quest airlock of the ISS at 1201 GMT. The astronauts had an emergency snorkel breathing system inside their helmets in case their spacesuit helmets filled with leaking water as happened for unexplained reasons on a previous EVA. While the astronauts finshed their primary task ahead of schedule astronaut Rick Mastracchio reported discomfort in his suit including cold feet so the EVA was completed early. The astronauts re-entered the Quest airlock at 1729 GMT where a spacesuit issue was discovered in Mastracchio’s suit raising concerns that water may again have got into a suit component. As a precaution a second EVA to continue the pump replacement work was delayed from 23 December to 24 December.
This second spacewalk went without a hitch on 24 December. It was again performed by US Astronauts Rick Mastracchio and Mike Hopkins. The EVA started at 1153 GMT. The astronauts left the Quest airlock on the station and during a 7 hour 30 minute session the two astronauts replaced the faulty ammonia coolant pump. The EVA ended at 1923 GMT as the astronauts re-entered the station via the same airlock.
The third spacewalk/EVA was performed by Cosmonauts Oleg Kotov and Sergey Ryazanski. This record setting Russian EVA of eight hours and seven minutes began at 1300 GMT on 27 December and ended at 2107 GMT. The cosmonauts exited from the Pirs module and initiallly installed two cameras/telescope imagers on a biaxial pointing platform that belonged to a Canadian commercial company, UrtheCast, that were designed to downlink Earth Observation imagery. The cameras failed to work however due to a telemetry fault, and cameras were returned to the Pirs module for further analysis meaning that the spacewalk was mainly for nothing. The cosmonauts also removed the Vsplesk experiment package and jettisoned it.
Phil Hylands contributed to this report.