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The Total Off-gassing test purpose is to determine the identity and quantity of trace gas contaminants offgassed in areas of spacecraft where the crew will breathe the atmosphere. Two different air sampling methods were adopted in parallel during the off-gassing tests on the Multi-Purpose Logistics Modules (MPLM) by Alenia Spazio. The first method, based on NASA (National Aeronautics and Space Administration) requirements, foresees storage of collected air samples into stainless steel pressure cylinders. The second method proposed by ESA (European Space Agency), uses trace contaminants adsorption on Carbopack™ filled ceramic tubes. Sample lines route the samples collected inside the MPLM cabin, to the respective external collection points. Successively, the stored samples are chemically analyzed by Gas Chromatography / Mass Spectrometry (GC/MS) techniques and the module offgassing rates are calculated.

Manned Space Systems are usually designed to support the crew atmospheric conditions equivalent to those at sea level. In phases with frequent Extra Vehicular Activities (EVA), a reduced pressure environment is preferable to facilitate the EVA suit prebreathing procedures. The Columbus Attached Pressurised Module (APM) will face both pressure scenarios during its life. Operation at different pressure levels primarily affects the performance of the Environmental Control System (ECS) of the pressurised elements. A lower air density results in reduced heat exchange, adversely affecting both the crew comfort and the electronics air cooling. This paper reports the results of a study performed to identify the constraints and the numerous potential problem areas related to APM operations at reduced pressure. Effects of the reduced pressure on the environmental parameters have been investigated.

The Columbus Attached Pressurised Module (APM) is intended to support a shirt-sleeve environment for crew activities. Top level requirements therefore define a cabin air temperature and humidity range (the so-called “Comfort Box”), extreme air velocities for ventilation in the centra aisle, maximum mean radiant temperature of the cabin walls. Air temperature selectability has to be ensured with adequate accuracy across the whole range. The APM environmental control system, in particular the Temperature and Humidity Control (THC) system, is designed and verified against these parameters. Cabin thermal conditions can be evaluated by the APM Integrated Overall Thermal Mathematical Model (IOTMM), representing the general thermal behaviour of the APM, including the THC system. Heat loads due to APM subsystem equipment and payloads, solar flux and the crew itself have been considered in the analyses.