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A novel method to calculate linear conductors for thermal lumped parameter (TLP) models has been developed and prototyped by ESA. The method, the so called “Far-Field” approach, is a generic empirical method leading to linear conductors that are directly comparable to conductors derived using the traditional TLP formulation, well known to space thermal engineers. One of the benefits over alternative approaches is that, even for non-trivial shapes, this method leads to a mathematical model that the engineer can fully understand and, if needed, easily modify and extend. This paper starts by presenting an overview of the Far-Field methodology and then focuses in detail on the implementation and validation of the module within the thermal-radiative software ESARAD. Extensive validation has been carried out using models ranging from simple geometries, which can be easily mapped to analytical solutions, to more complex geometries.

Over the last years the open data exchange standards STEP-TAS (Thermal Analysis for Space) and STEP-NRF (Network-model Results Format) have been developed under ESA funding. Both standards are based on ISO 10303/STEP. STEP-TAS converters have been implemented in many different thermal-radiative analysis packages, both in Europe and the US, in either pre-production or prototype versions. For practical use the converters needed to gain robustness and scaleability to exchange large models. In order to achieve the required industrial robustness and at the same time to lower as much as possible the barriers to implement the protocol, ESA has taken the following measures: 1. Simplify considerably the NRF and TAS protocols, taking into account all lessons learned from the earlier developments. 2.

STEP-TAS and STEP-NRF are two companion, open standards for electronic exchange and archival of space engineering data based on STEP (ISO-10303) technology: STEP-TAS: Definition of space missions and models used in thermal analysis. STEP-NRF: Discipline-independent protocol for the definition of analysis, test or operation cases/models and the bulk results produced by running such cases/models. Associated with these standards, some high-level programs have been developed for helping with the implementation of these protocols into user applications. Now, the STEP-TAS standard has started its industrial deployment phase in Europe with the incorporation into thermal software like ESARAD and THERMICA, while the first STEP-NRF proof-of concept implementations have started with software like CORATHERM from Alcatel Space.

This paper presents the approach, the status and the future of two companion open standards for electronic exchange and archival of space engineering data: 1) STEP-NRF - Network-model Results Format - a discipline-independent protocol for the definitions of analysis, test or operation cases/models and the bulk results produced by running such cases/models. A generic network-model formulation is used to represent the different elements of an analysis model, a test article or an operational product and where applicable their environment. The results are stored as valued properties for particular network-model components for a particular state during a run. Properties can be of scalar, vector or tensor type. Special care is taken to ensure efficient storage of sparse data structures. 2) STEP-TAS - Thermal Analysis for Space - a protocol for the definitions of space missions and models used in thermal analysis.

This paper reports on the first phase of the development of the STEP-based Thermal Analysis for Space Application Protocol (STEP-TAS AP), an initiative by the European Space Agency (ESA) in collaboration with the French Space Agency (CNES). The activity responds to the industrial need to have a standard, quality means for the electronic exchange of thermal models between the various companies and organisations involved in space projects and also to improve the possibility to exchange data with tools of other engineering disciplines (notably CAD tools). The development is based on the use of STEP, which is the casual name for the ISO 10303 Standard for Exchange of Product Model Data. The following topics are highlighted: The production of a common description of the information exchange requirements in the space thermal analysis domain, based on work previously initiated by ESA and CNES.

The ICETAS initiative from ESA aims to provide the European space community with: A framework for development and integration of software tools supporting the thermal design, analysis and verification process for space applications. Effective exchange of thermal analysis models and data. In phase 2 of ICETAS a consistent set of user requirements was formulated, derived from so-called Use Cases. The Use Cases give step-by-step descriptions of the interaction between the thermal engineer and the software system. ICETAS covers the thermal engineering process all the way from requirements analysis and conceptual design to test evaluation and flight support. The user requirements activity was followed by the definition of a complete, object-oriented information model (the Common Data Structure - CDS) capturing all data entities and associations needed in the discipline.