A spacewalk to fix a cooling system that broke on the International Space Station over the weekend has again been delayed and will now take place Saturday, US space agency NASA said, dpa reported.
NASA decided to push back the spacewalk to allow astronauts more time to prepare for the complicated procedure. It had first hoped to complete it Thursday when an earlier spacewalk had already been scheduled and has since been twice pushed back by a day.
At least two spacewalks will be needed to replace the system with a spare part stored outside the ISS, and a second spacewalk would now take place Wednesday.
Astronauts Doug Wheelock and Tracy Caldwell Dyson will perform the spacewalk and had already trained to replace this part, in NASA's efforts to prepare ISS crew members for contingencies aboard the station, said ISS programme manager Mike Suffredini.
The first spacewalk now set for 1055 GMT Saturday would focus on removing the 350-kilogramme broken part and replacing it with a spare stored about 10 metres away. The second spacewalk would be needed to hook up cables and wire the part into the station.
The system is one of two used to keep electronics on the ISS from overheating. On Saturday, alarms were triggered signalling that the ammonia-based refrigeration system on the ISS had failed due to a power surge.