International Space Station Stable Despite Cooling Issues
NASA reported Aug. 1 that "Mission Operations personnel and ISS program management met Sunday morning to discuss the status of the loss of cooling loop A ... on the International Space Station when a circuit breaker tripped just before 7.p.m. Central time Saturday night that resulted in the failure of the Pump Module for loop A that feeds ammonia to maintain the proper cooling for systems and avionics."
The space agency reported, "An attempt overnight Sunday to close the circuit breaker and restart the Pump Module was not successful."
The statement continued:
"To protect for spacewalk activity later this week, the flight control team plans to vent residual ammonia in the lines between the Ammonia Tank Assembly on the S1 truss and the failed Pump Module Tuesday to prepare for the module's eventual replacement.
The tasks originally planned for Thursday's previously scheduled spacewalk by [Expedition 24 crewmembers Doug] Wheelock and [Tracy] Caldwell Dyson, to install a power extension cable ... [and] a Power and Data Grapple Fixture to the Zarya module to support future robotics work will be deferred to a later date."
NASA also explained, "To replace the Pump Module and structurally bolt it into place on the S1 truss" will require "an additional spacewalk by the duo two or three days later to mate fluid and electrical connections."
The agency also said:
"One of two Control Moment Gyroscopes (CMG 1) that was taken off line Saturday night was spun up once again this morning, enabling the station to operate with three of four CMGs to electrically control the orientation of the outpost. Temperatures on the Main Bus Switching Units, which route power to various systems, are a little higher than normal, but well within normal parameters and are stable."
NASA reported the station is in a "stable configuration with most systems receiving cooling and many systems operating with redundancy following the installation of jumper cables from the Destiny Lab's power system overnight. The crew is not in any danger and is monitoring systems and relaxing on an otherwise off duty-day."
Finally, NASA announced, "The flight control and management teams today approved a preliminary plan to replace a planned spacewalk Thursday ... with at least two spacewalks to swap out the failed Pump Module that resides on the station's S1 truss. There are two spare Pump Modules on stowage platforms on the station's truss. The replacement module under consideration for replacement resides on External Stowage Platform 2, which is adjacent to the Quest airlock. The crew is being informed that replanning for alternate spacewalk activity is under way."