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In space, the radiative heat transfer is the dominant phenomenon. Therefore, the spacecraft thermal analysis pays particular attention to the computation of the radiative terms of the heat transfer equation (radiative couplings and external heat fluxes). In the European space industry, widely automated softwares such as THERMICA (distributed by MMS1), based on a Monte-Carlo Ray-Tracing method simulating the behaviour of photons, have permitted to reach a satisfactory level of accuracy while keeping an acceptable cpu-time consumption. However, even if results converge when the number of photons increases, the adequate number of photons required to achieve a given accuracy is not available. This lack of information may produce “hidden errors” in the radiative model. To solve this problem, a statistical method, based on the central limit theorem, was developed in 1992 [2] and improved in 1993 [5], in order to compute confidence intervals from the variance of the results.

The usual concern of an industrial company involved in a competition environment is to produce at lower cost and in shorter time while preserving a high quality standard. Because of this, particular attention must be paid to thermal analyses which in the space industry are very time and effort consuming tasks, and have been suffering for long of a lack of an efficient software analysis tool. This paper shows how an integrated thermal chain designed at the same time on the basis of operational tools and of the most recent hardware and software improvements can tackle this problem, opening new outlooks for thermal engineering for building innovative space systems.

In space engineering, a thorough thermal analysis on a spacecraft is necessary to evaluate structural stresses, and above all thermoelastic displacements (e.g. instrument pointing). The main problem of such an analysis lies in the fact that thermal and mechanical engineers do not use the same software tools. Thermal loadcases on structural models are all the more difficult to obtain that models become more and more complex. Interpolating temperatures by hand is now tedious and an inaccurate task. MATRA MARCONI SPACE recently developed an original tool that can automatically interpolate a 3D temperature map. This tool, in the very near future, will make thermal and mechanical engineers work together without throwing back into questions their methodologies for solving this kind of problem.