Introduction

As the number of space vehicles increases, and those vehicles operate with greater power over longer life spans, their thermal management becomes ever more critical. Accompanying this trend is an unprecedented need for spacecraft size and weight reduction, and recurring launch costs are strongly tied to this need. However, reduced weight leads to higher power densities, and waste-heat dissipation densities have grown by orders of magnitude as smaller, more powerful electronics are continually flown, thanks to technology advances in semiconductor devices. In recent years, spacecraft power dissipation has increased relative to the weight of the thermal control subsystem as well as the spacecraft.

Thermal design problems that deal with these issues must be solved quickly, and, more important, the solutions must provide highly producible, cost-effective products required for all spacecraft and instruments. These trends drive development of advanced thermal control devices, materials, and techniques. ^[20.1] Accordingly, thermal control technologies must evolve over time.

The development effort is not, however, without its challenges. For example, one difficulty often encountered is the development of effective performance metrics for new thermal control technology. Many new thermal control technologies do not simply replace existing ones, but rather offer entirely new options for the design of...