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Columbus has been delivered to Kennedy Space Center (KSC) in summer 2006 for final integration, test and mission preparation. In the frame of these “last” phase activities also the Active Thermal Control System (ATCS) had to be finalized and prepared for the launch resp. mission. Due to unexpected late failures resp. malfunctions detected on component/unit level of the ATCS, refurbishment, integration / exchange of the relevant components and re-testing of their system level functions had to be done. Moreover, the still outstanding system level fluid leakage test of the ATCS had to be revised and completed. In addition to the required late refurbishment, integration and test activities, in certain cases also operational workarounds had to be evaluated. They should help to cope with similar contingency situations during operation of the ATCS on-orbit.

Verification of the Integrated Overall Thermal Mathematical Model (IOTMM) is one of the last tasks in the thermal and environmental control area of the Columbus module. For this purpose a specific test covering as well thermal-hydraulic performance tests as Environmental Control and Life Support (ECLS) cabin temperature control functions has been defined and performed on the european Columbus Protoflight Model (PFM) in Bremen in 2003. This Environmental Control System test was successful for all Active Thermal Control System (ATCS) related thermal-hydraulic functions and could provide sufficient data for a proper IOTMM correlation. However, it failed to verify the ECLS related functions as cabin temperature control and ventilation. Data, which have been generated during this first test, could not be used for a successful IOTMM correlation related to ECLS subsystem performance and modelling.