TSCALC is a computer program that calculates the space sink temp- erature (TS), defined as the equilibrium temp- erature of a spacecraft heat-dissipation radiator or other object nominally isolated except for radiative exchange of heat with the Sun, or any star for which equilibrium sink temp- eratures are to be evaluated; planets, in the neighborhood of which the thermal environment is of interest; and interstellar space. TSCALC utilizes the gray-body Stefan- Boltzmann equation and the equations for radiant fluxes as functions of distances between, and orientations of, bodies engaged in radiative exchange. Factors taken into account by TSCALC include (1) distances from the spacecraft to the Sun and any planets in the neighborhood of which a spacecraft has to operate; (2) angles between the radiator surface and lines of sight to the Sun and a neighboring planet; (3) the ratio between solar absorptivity and thermal emissivity of the radiator surface; (4) the “View Factor to Space,” which is a function of the solid angle subtended by interstellar space as viewed from the radiator; (5) the luminosity, L, of the stellar heat source (L = 3.86 × 1026 W for the Sun); and (6) the albedos of planets, in the vicinity of which a spacecraft will operate. The TS computed by TSCALC can be used, along with the thermophysical properties of the radiator material and the temperature of a spacecraft heat source, as inputs to spacecraft-radiator design code that computes the area of a radiator needed to dissipate a given heat load while operating at a given temperature >TS.

This work was done by Albert J. Juhasz of Glenn Research Center.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Commercial Technology Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-16852.

NASA Tech Briefs Magazine

This article first appeared in the October, 2002 issue of NASA Tech Briefs Magazine.

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