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Configurations similar to ’V-Grooves’, as already applied for radiators, can also insulate complete spacecraft and telescopes from solar radiation or hot modules several orders of magnitude better than the usual MLI. The specularity of surfaces contributes to the reduction of the radiation between the shields and thus improves the insulation. In this paper absorption factors between specularly and diffusely reflecting conical and rectangular areas are presented versus the ’V-angle’ in order to design such insulating configurations. Monte Carlo methods cannot be applied for very complex configurations if the number of surfaces is too large. The introduction of auxiliary areas with 100% specular reflectivity helps to simplify these geometries. Herein, the principle of this technique is first explained and proven by two examples of V-grooves. Then this method is applied for a specific configuration: three parallel plates which each have more than 8000 holes.

Equations for conductive shape factors are presented. The products of these factors with conductivity give the conductances of a thermal model. Four new equations treat: the truncated hollow cone with variable wall thickness, the truncated full cone, the trapezium and the cube. Since the equation for spherical segments is usually not given in literature it is also presented. The shape factors found by these equations are compared with results determined by the ’area/distance’ equation, by TMG and/or by equations from literature. The TMG programm with automatic meshing was used with varying node numbers. It is shown that many nodes are needed for most of the chosen examples in order to obtain a convergence to a sufficient precise result. The practical advantage of the presented equations is thus to allow a reduction of the number of nodes for a desired precision of the model.

About 40 papers treating multilayer insulations were studied and compared. Most of these papers present heat transfer measurements in addition to thermal analysis. Here the equations are given which are required for an evaluation of the measurements and in particular for comparisons. Equations are presented which are required to predict the influences of the packing density, temperatures, fraction of perforation area and interstitial pressure. The equation giving gas conductivity versus pressure is modified according to measurements. In space the interstitial pressure is usually below 0.01 Pa und the heat transfer can be expressed as the sum of a conductive and a radiative term. The equation finally proposed for spacecraft permits to consider the influence of temperature, number of layers, blanket size and perforation area.

The Huygens thermal control concept was developed in the B1 and B2 study phases between Jan. 91 and Feb. 92. This paper describes the actual thermal design and mass budget. It also covers the most important trade-offs, concept modifications and parameter studies performed prior to the actual design. Natural convection tests on two boxes having the typical shape of Huygens boxes and conductivity tests with Basotect foam around a standing and a hanging box were made in 1991 at MBB. The foam keeps the descent module sufficiently warm during the descent phase to Titan's surface. The paper describes these tests, presents the test evaluations and compares measured and calculated convection rates and conductivities. Special tests for the selection, treatment and placement of the foam are described.