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As a consequence of the continuously increasing complexity of design, development and qualification of modern spacecraft subsystems, computer aided tools become increasingly important for solving the various engineering tasks in these fields. In the framework of development tasks for satellites and space stations, e.g. ERS-I/II, ROSAT, CLUSTER, SOHO, COLUMBUS-ECLSS, and HERMES a software environment has been developed at Dornier GmbH in recent years, which allows thermal analysis, thermal control and space environment control for system simulation as well as for detained component level simulation, monitoring and testdata evaluation. COSITHERM is a modular software package for the prediction of thermal radiation effects. SIMTAS can be used for detailed analysis of single system components as well as for the prediction of system response of arbitrarily connect components.

Manned space laboratories like the US Space Station Freedom or the european COLUMBUS APM are equipped with so-called racks for subsystem and payload accommodation. An important resource is air for cooling the unit internal heat sources, the avionics air. Each unit inside the rack must be supplied with sufficient amount of air to cool down the unit to the allowable maximum temperature. In the course of the COLUMBUS ECLSS project, a thermohydraulic mathematical model (THMM) of a representative COLUMBUS rack was developed to analyse and optimise the distribution of avionics air inside this rack. A sensitivity and accuracy study was performed to determine the accuracy range of the calculated avionics air flow rate distribution to the units. These calculations were then compared to measurement results gained in a rack airflow distribution test, which was performed with an equipped COLUMBUS subsystem rack to show the pressure distribution inside the rack.

This paper discusses the capabilities of the ABLAT software which has been developed by ERC and Dornier for the European Space Agency. The software provides an ablation modelling capability for the ESATAN thermal analyser and consists of two sections: i. A stand-alone preprocessor allowing specification of the ablation model. This has both an X11/OSF Motif and a command line interface. ii. An integrated solver capability within the ESATAN system, allowing transient analysis of an ablating surface in conjunction with a standard thermal model. After a brief overview of the major aims of the development, the software is discussed from two main points of view, the user interface facilities (how the user defines the model to the system), and the calculation facilities (what can be calculated, and how are these calculations performed).

Potential fires in the COLUMBUS Attached Pressurized Module (APM) shall be extinguished by reducing the O2 concentration in the atmosphere below 15 %. For this purpose a CO2-distribution system is foreseen. It injects CO2 stored in a tank into the volume where fire is to be extinguished. Due to its dimensions the most critical of these volumes is the subfloor with the stand-off areas. To investigate the fire suppression process a detailed three dimensional computational fluid dynamic analysis (CFD-analysis) was performed. The transient CO2-distribution mechanisms, forced convection and diffusion, were analyzed to examine the feasibility of the foreseen system and to optimize it. In this paper the governing physical processes and their implementation in the mathematical model of the problem are described. The very complex inlet conditions - speed of sound, tiny nozzles - are examined in detail to investigate a proper method for implementation in the mathematical model.

ESABASE/SUNLIGHT is a software tool to calculate illumination, effective illumination, exposure time, incident electromagnetic power, absorbed electromagnetic energy for spacecraft surfaces during planet orbiting missions considering sun and planet irradiation, effects of eclipse and self-shading, multireflections, transmission, pointing and (variable) geometry. Calculation applies a fast Monte Carlo raytracing algorithm and is based on wavelength dependent spectra and material properties. ESABASE/SUNLIGHT is fully integrated in the CAE-frame ESABASE which offers a powerful geometry specification language, orbit generator, pointing facility and advanced libraries as well as gateway, pre-, postprocessing and display tools with the benefits of standardisation and exchange to other analysis tools.