Tiny microelectromechanical systems (MEMS) may be the key to maintaining giant space-based structures, such as solar collectors, according to researchers Steve Tung and Larry Roe at the University of Arkansas (Fayetteville). Although such space-based solar collectors could be many square miles in size, tiny MEMS devices could help keep them oriented correctly to ensure their long-term operation. Tung, Roe, and graduate student Scott Witherspoon are working with David Maynard of the Jet Propulsion Laboratory, NASA's program manager for space solar power, to examine the potential benefits of MEMS in such space-based applications.
"It can cost from $5000 to $50,000 per pound to put an object into space," says Roe, associate professor of mechanical engineering. "Because inflatable structures minimize mass and volume, they are far less expensive and will become increasingly important in near-term and future space missions." An inflatable structure can be folded and compressed to the size of a desk, and then, when inflated, become a solar collector 1-mile wide. However, such a large structure is subject to radiation damage and puncture from micrometeoriods. The structure could also drift and turn away slightly from its original orientation. For this reason, constant monitoring is necessary to ensure the continued integrity and long-term performance of the structure.
That is where Tung, assistant professor of mechanical engineering, comes in. He has developed a flexible MEMS device that can be integrated into the fabric of an inflatable structure. Although it is less than 1 inch (2.5 cm) long, it can monitor both local conditions such as strain or vibration and global conditions such as motion of the system. "Traditional sensor modules are heavy, rigid and expensive," Tung adds. "But a sensor module for an inflatable structure must be low mass and flexible. Just as important, it must be simple to install and of low cost."
Tung and Roe report that they also plant to incorporate actuators into their MEMS device that will allow it to take corrective action when it locates a problem.