TABLE OF CONTENTS The purpose of a spacecraft thermal control subsystem is to maintain all of the elements of a spacecraft system within their temperature limits for all mission phases. To provide a design that meets the temperature requirements of the spacecraft, the designer must account for heat inputs from many different sources. These heat sources include the sun, the Earth, and heat dissipation from electrical and electronic components onboard the spacecraft. In most instances the heat inputs are highly variable with time. For example, the magnitude of direct solar heating on a spacecraft surface can vary from 1371 W/m 2 (when the surface normal is parallel to the solar vector) to zero (when the spacecraft is in the shadow of the Earth). Also, the geometry of a spacecraft is generally very complex. These characteristics cause the thermal analyses that define the thermal behavior of spacecraft to be extremely complicated, involving transient solutions for problems with complex geometry. This leads to numerical solutions using specialized computer programs. Therefore, on a typical spacecraft project, the computer usage by the thermal control group will be relatively high. However, the thermal control subsystem accounts for only about 2 5% of the total spacecraft cost and about the same percentage of the weight.
Engineers assigned to spacecraft thermal control groups typically will have...
