"Earlier Wednesday, the pump module on one of the space station's two external cooling loops automatically shut down when it reached pre-set temperature limits. These loops circulate ammonia outside the station to keep both internal and external equipment cool. The flight control teams worked to get the cooling loop back up and running, and they suspect a flow control valve actually inside the pump module itself might not be functioning correctly."
"Mission managers have deferred the decision on whether to proceed with or postpone the launch of the Orbital Sciences' Cygnus commercial cargo craft until more is known about the flow control valve issue. Cygnus is currently scheduled to launch Dec. 18 from Wallops Flight Facility in Virginia and rendezvous with the station on Dec. 21."