A quarterly research and development magazine.
Satellite designers pay special attention to electronics temperatures. If circuit boards get too hot, they can fail. If batteries get too cold, they can degrade faster or perform intermittently.
The ST5 mission demonstrated the benefits of
using a constellation of spacecraft, as shown in this NASA
drawing, to perform scientific studies of the beautiful auroral
displays that occur near Earth’s polar regions.Temperatures inside satellites can fluctuate to both extremes, heating up when in sunlight or cooling way down when in Earth’s shadow, for example. The heat generated by the electronics themselves can be trapped inside the satellite. Larger satellites have sophisticated, and heftier, thermal control systems. Smaller ones, like the 55-pound Space Technology 5 experimental microsatellites — each roughly the size of a wedding cake — require smaller, lighter-weight, and, ideally, lower-tech approaches.
A collaboration was launched, and Sandia project lead Jim Allen and a team of MEMS designers worked with the Johns Hopkins researchers to design, using Sandia’s SUMMiT V™ technology, a MEMS device featuring a moving grillwork of shutters with slats that are six microns wide and 1,800 microns long. (A human hair is about 100 microns thick.)
The arrays of small shutters, moved back and forth by electrostatic actuators, expose either the gilded and highly reflective grillwork surface or a dark silicon substrate to maximize or minimize heat transfer through the satellite’s skin as needed. The electrostatic actuators — themselves arrays of intermeshing, spring-loaded comb’s teeth pulled together by electrostatic attraction — are a proven micromotion staple also developed at Sandia.