Discussion of the General Electric proposal to develop a computer program to select thermal coatings for passive temperature control of satellites

The General Electric Company, Missiles and Space Division, submitted/a proposal to NASA for the development of an IBM 7094 computer program which would select the exterior surface
coatings for passively controlling spacecraft temperatures. G. E. claims that the "trial and error" procedures currently used can be accomplished more rationally and can therefore be programmed for a digital computer. In the ASME paper, 63-HT-41, which was presented at the ASME-AIChE Heat Transfer Conference at Boston in August, 1963, Costello, Harper, and Cline, described the procedures that have been used at G. E. to develop a coating selection program subject to the following restrictions:

1. Steady-state conditions prevail,
2. Heat transfer occurs by radiation only,
3. Temperatures are optimized at only one interior point in the spacecraft, an d
4. Only the solar absorptance of the external coatings is varied to optimize temperature. The emittance must remain constant at initially specified values.

General Electric proposes to develop a generalized program in three steps:

1. The program would vary both solar absorptance and hemispherical emittance to obtain the optimum coating patterns;
2. Temperatures would be optimized at more than one interior point; and
3. The equations would be modified to account for both conduction and radiation heat transfer.

In the development of the general program, the scope would be restricted to steady-state heat transfer. Since the thermal designs of most spacecraft are based primarily on nearly equilibrium conditions, the proposed program could have wide application. An obvious extension of the proposed program would be to account for transient temperatures.