Air Force Research Laboratory engineers create thermal control system for space use

by Heyward Burnette

Air Force Research Laboratory Materials and Manufacturing Directorate

6/17/2008 – WRIGHT-PATTERSON AIR FORCE BASE, Ohio (AFPN) — Air Force Research Laboratory engineers here have successfully integrated two existing technologies to create a thermal emission management system suitable for space use.

Achieving operationally responsive space capabilities requires versatile satellites that can adapt as needed to accomplish multiple missions, and an integral part of such adaptable satellites is a thermal control system enabling real-time, on-orbit temperature control of the spacecraft.

In maintaining appropriate spacecraft temperature, the system ensures proper functioning of onboard equipment. AFRL’s newly developed thermal emission management system is particularly well-suited for space deployment, since it requires very little power, is compact and has minimal data storage requirements.

Active thermal management devices generally rely on heaters and mechanical refrigerators to control spacecraft temperature. While these active systems can achieve real-time temperature changes to protect spacecraft from extreme environments, they unfortunately require power supplies and are complex and heavy. Conversely, AFRL’s new technology not only requires little operating power, but weighs considerably less than state-of-the-art active control systems. The integrated device also offers the advantage of on-demand switching between passive and active thermal control.

In creating the efficient new thermal control capability, AFRL engineers paired two technologies developed under separate Small Business Innovation Research contracts. Specifically, the new system combines the functionality of a Sensortek, Inc., electrostatic radiator, or ESR, device with a heat-flux-based emissivity measuring method developed by Advanced Thermal and Environmental Concepts, Inc.

After merging the two technologies, AFRL engineers mounted the resultant device inside a large vacuum chamber in order to test it in a simulated space environment. Upon obtaining a steady-state temperature, the test team supplied voltage to one side of the ESR structure, causing the membrane to draw down into contact with the ESR structure’s rigid surface. The embedded heat flux sensor demonstrated a very fast response time, so the engineers were able to monitor the hybrid device’s emissivity throughout the temperature change. The results acquired from the ESR structure reflected significant differences in emissivity values — such large differences are a requirement for systems designed to facilitate a wide range of active thermal control.

Subsequent to these successful tests, the AFRL-developed device underwent incorporation into the Materials (on the) International Space Station Experiment-6, or MISSE-6, assembly, launched earlier this year aboard the Space Shuttle Endeavor. MISSE-6 mission results will aid scientists in determining the new system’s viable use for official missions.