TABLE OF CONTENTS The thermal control engineer's task is to maintain the temperature of all spacecraft components within appropriate limits over the mission lifetime, subject to a given range of environmental conditions and operating modes. Thermal control as a space vehicle design discipline is unusual in that, given clever technique and reasonable circumstances, the thermal "system" may require very little special-purpose spacecraft hardware. More demanding missions may require extra equipment such as radiators, heat pipes, etc., to be discussed in the following sections. In all cases, however, the required analysis will involve the thermal control engineer in the design of nearly all other onboard subsystems.
As with attitude control, thermal control techniques may be broadly grouped within two classes, passive and active, with the former preferred when possible because of simplicity, reliability, and cost. Passive control includes the use of sunshades and cooling fins, special paint or coatings, insulating blankets, heat pipes, and tailoring of the geometric design to achieve both an acceptable global energy balance and local thermal properties.
When the mission requirements are too severe for passive techniques, active control of spacecraft temperatures on a local or global basis will be employed. This may involve the use of heating or cooling devices, actively pumped fluid loops, adjustable louvers or shutters, radiators, or alteration of the spacecraft attitude to attain suitable conditions.
Most readers will recall the basic heat transfer mechanisms: conduction, convection, and radiation. Broadly generalizing, it may be said that the overall energy balance between a spacecraft and...
