Qualification of Infrared Array Grid using Tubular Heaters as a Reliable Tool on Space Simulation

Paper number

IAC-07-C2.7.05

Author

Dr. Jose Sergio Almeida, Instituto Nacional de Pesquisas Espaciais (INPE), Brazil

Coauthor

M.B. Santos, Brazil

Coauthor

D.L. Panissi, Brazil

Coauthor

E.C. Garcia, Instituto Tecnológico de Aeronáutica - ITA, Brazil

Year

2007

Abstract

Space Simulation dedicated to the qualification and acceptance of space flight hardware is known to be expensive and of long-duration testing activities.
Reliable and more practical alternatives to the high-cost Solar Simulation technique are frequently in search by spacecraft testing laboratories located around the world.
This paper presents the work carried out at the laboratories of the Brazilian Institute for Space Research concerning the qualification tests of the infrared array grid using tubular heaters.
Although a general philosophy using this kind of technique has been used by other laboratories, this particular work is focused on the most critical feature of the technique, i.e., the obtaining of the highest uniformity on the radiative flux produced by the tubular heater grid, as incident to the spacecraft surface during its orbital simulation.
In order to produce thermal radiative heat flux, a number of tubular heaters are arranged in a kind of open-top, open-bottom box. The internal and the external walls of this box have specific surface finishing for the best performance of the heat flux producing device.
The main part of the qualification process of this infrared array grid is accomplished by positioning a large quantity of pre-calibrated radiometers in a surface maintained at a certain distance of the tubular heaters array, in order to precisely measure the absorbed heat flux. Considering that a larger number of tubular heaters will produce better uniformity of heat flux, whilst during the simulation of the eclipse condition this will also create a limited view-factor from the spacecraft surface to the vacuum chamber cold walls, the opposite situation will also be true. So, finding the optimum layout of the tubular heaters in terms of quantity, distance among them, etc., and also the distance to the spacecraft surface, the geometrical characteristics and properties of the box surfaces, the power applied to each one of the heaters, these are the main objectives of this work.
In order to analyze the distinct performance of the several geometrical proposals and physical characteristics of the IR grid, this apparatus including the radiometers was taken to a vacuum chamber with cold walls where several thermal-vacuum tests were performed, and a significant amount of data was recorded, analyzed and compared to computing modeling to find out the most appropriate arrangement of the whole set-up. All this information is presented in this paper.

Abstract document

IAC-07-C2.7.05.pdf

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