Astronauts removed a malfunctioning International Space Station cooling pump in a spacewalk Wednesday after an initial attempt failed Sunday. The astronauts will need to install a new pump next week. Until then, the space station crew must curtail its research work.
Two crew members from the International Space Station took a major step toward replacing a critical piece of the orbiting laboratory's cooling system today, following a failed attempt Sunday.
During a 7 hour, 26 minute spacewalk, Tracy Caldwell Dyson and Army Col. Douglas Wheelock removed a coolant pump on the outside of the station, clearing the way for another spacewalk Monday to install an on-board spare.
The pump failed unexpectedly on July 31, cutting in half the station's capacity to shed heat generated by its electrical systems, laboratory experiments, as well as six active astronauts.
The six crewmembers aboard the station were never in danger, NASA officials have emphasized. But the outage forced mission managers to significantly curtail research activities on the orbiting lab.
"Lots of smiles down here guys," came the word from mission control as Dr. Caldwell Dyson and Colonel Wheelock sat in the air lock after the spacewalk.
Swapping the coolant pumps represents one of the 14 most difficult maintenance jobs station crews face. Spacewalks ordinarily take weeks to plan because they require detailed choreography. But the urgency of returning the station's cooling system to full capacity prompted planners to accelerate the process for a repair job astronauts had trained for with only the broadest of brush strokes.
For instance, last night, engineers were still working on procedures governing the use of the station's robotic arm for today's effort. The broad-brush plan for removal of the pump that astronauts used in training had assumed that the arm wouldn't be available.
Clamping an astronaut to the end of the robotic arm, then having him hold a 780-pound pump steady while a crew member inside the station moves the two to the spot where planners want to deposit the pump – that's a procedure planners would rather not develop at the last minute, mission officials said.