14 DAY TRIAL // The cooling situation is acceptable on the ISS, after the loss of cooling loop A, on Saturday night. On Sunday morning, the Mission Operations staff and ISS Program management met and discussed the issue of the cooling on the Station. As a circuit breaker tripped on Saturday, it caused a failure of the Pump Module for ammonia providing loop A, which maintains the cooling of the systems and avionics on the ISS.
Despite the unsuccessful attempt of closing the circuit breaker and restarting the Pump Module on Sunday night, the station is in a stable configuration. Most systems receive cooling and many operate redundantly, as a result of the jumper cables from the Destiny Lab's power system's installation during the night.
The station operates with three out of four Control Moment Gyroscopes, as one of the two CMGs that was taken off line Saturday, has been spun up yesterday morning. The temperatures on the Main Bus Switching Units are a bit high, but within normal parameters and stable. The crew is safe and continues monitoring the systems.
On August 5, two of the crew members, Doug Wheelock and Tracy Caldwell Dyson, had a spacewalk planned. After the incident on Saturday, flight control and management teams came up with a preliminary plan to replace Thursday's mission with at least two spacewalks that will allow swapping out the failed Pump Module from the station's S1 truss.
On IIS's the stowage platforms there are two spare Pump Modules, and the one the crew needs is on the External Stowage Platform, next to the Quest airlock. Even though nothing has been settled, the most likely plan would need a first spacewalk on Thursday, so that Wheelock and Caldwell Dyson can replace the Pump Module and bolt it into place on the S1 truss. The second spacewalk would allow the two to mate fluid and electrical connections, in two or three days' time.
The mission originally planned for Thursday will be rescheduled, according to NASA.